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Sample records for prey infrared signals

  1. Signaling by decorating webs: luring prey or deterring predators?

    OpenAIRE

    Ren-Chung Cheng; I-Min Tso

    2007-01-01

    Many organisms convey false signals to mislead their prey or predators. Some orb-weaving spiders build conspicuous structures on webs called decorations. Web decorations and spider colorations are both suggested to be important signals involved in interactions between spiders and other organisms. There are several hypotheses about the functions of signaling by decorations, among which prey attraction had received much support, but empirical evidence regarding predator defense is controversial...

  2. Predators are attracted to the olfactory signals of prey.

    Directory of Open Access Journals (Sweden)

    Nelika K Hughes

    2010-09-01

    Full Text Available Predator attraction to prey social signals can force prey to trade-off the social imperatives to communicate against the profound effect of predation on their future fitness. These tradeoffs underlie theories on the design and evolution of conspecific signalling systems and have received much attention in visual and acoustic signalling modes. Yet while most territorial mammals communicate using olfactory signals and olfactory hunting is widespread in predators, evidence for the attraction of predators to prey olfactory signals under field conditions is lacking.To redress this fundamental issue, we examined the attraction of free-roaming predators to discrete patches of scents collected from groups of two and six adult, male house mice, Mus domesticus, which primarily communicate through olfaction. Olfactorily-hunting predators were rapidly attracted to mouse scent signals, visiting mouse scented locations sooner, and in greater number, than control locations. There were no effects of signal concentration on predator attraction to their prey's signals.This implies that communication will be costly if conspecific receivers and eavesdropping predators are simultaneously attracted to a signal. Significantly, our results also suggest that receivers may be at greater risk of predation when communicating than signallers, as receivers must visit risky patches of scent to perform their half of the communication equation, while signallers need not.

  3. Predator and prey perception in copepods due to hydromechanical signals

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Visser, Andre

    1999-01-01

    of the different components of the fluid disturbance. We use this model to argue that prey perception depends on the absolute magnitude of the fluid velocity generated by the moving prey, while predator perception depends on the magnitude of one or several of the components of the fluid velocity gradients...... (deformation rate, vorticity, acceleration) generated by the predator. On the assumption that hydrodynamic disturbances are perceived through the mechanical bending of sensory setae, we estimate the magnitude of the signal strength due to each of the fluid disturbance components. We then derive equations...... for reaction distances as a function of threshold signal strength and the size and velocity of the prey or predator. We provide a conceptual framework for quantifying threshold signal strengths and, hence, perception distances. The model is illustrated by several examples, and we demonstrate, for example, (1...

  4. Infrared tomographic PIV and 3D motion tracking system applied to aquatic predator–prey interaction

    International Nuclear Information System (INIS)

    Adhikari, Deepak; Longmire, Ellen K

    2013-01-01

    Infrared tomographic PIV and 3D motion tracking are combined to measure evolving volumetric velocity fields and organism trajectories during aquatic predator–prey interactions. The technique was used to study zebrafish foraging on both non-evasive and evasive prey species. Measurement volumes of 22.5 mm × 10.5 mm × 12 mm were reconstructed from images captured on a set of four high-speed cameras. To obtain accurate fluid velocity vectors within each volume, fish were first masked out using an automated visual hull method. Fish and prey locations were identified independently from the same image sets and tracked separately within the measurement volume. Experiments demonstrated that fish were not influenced by the infrared laser illumination or the tracer particles. Results showed that the zebrafish used different strategies, suction and ram feeding, for successful capture of non-evasive and evasive prey, respectively. The two strategies yielded different variations in fluid velocity between the fish mouth and the prey. In general, the results suggest that the local flow field, the direction of prey locomotion with respect to the predator and the relative accelerations and speeds of the predator and prey may all be significant in determining predation success. (paper)

  5. Signal conflict in spider webs driven by predators and prey

    OpenAIRE

    Blackledge, T. A.

    1998-01-01

    Variation in the sensory physiologies of organisms can bias the receptions of signals, driving the direction of signal evolution. Sensory drive in the evolution of signals may be particularly important for organisms that confront trade-offs in signal design between the need for conspicuousness to allow effective transfer of information and the need for crypsis of the signal to unintended receivers. Several genera of orb-weaving spiders include conspicuous silk designs, stabilimenta, in the ce...

  6. Molecular diagnostics reveal spiders that exploit prey vibrational signals used in sexual communication.

    Science.gov (United States)

    Virant-Doberlet, Meta; King, R Andrew; Polajnar, Jernej; Symondson, William O C

    2011-05-01

    Vibrational signalling is a widespread form of animal communication and, in the form of sexual communication, has been generally regarded as inherently short-range and a private communication channel, free from eavesdropping by generalist predators. A combination of fieldwork and laboratory experiments was used to test the hypothesis that predators can intercept and exploit such signals. First, we developed and characterized PCR primers specific for leafhoppers of the genus Aphrodes and specifically for the species Aphrodes makarovi. Spiders were collected from sites where leafhoppers were present and screened with these primers to establish which spider species were significant predators of this species during the mating period of these leafhoppers. Analysis using PCR of the gut contents of tangle-web spiders, Enoplognatha ovata (Theridiidae), showed that they consume leafhoppers in the field at a greater rate when signalling adults were present than when nymphs were dominant, suggesting that the spiders were using these vibrations signals to find their prey. Playback and microcosm experiments then showed that E. ovata can use the vibrational signals of male leafhoppers as a cue during foraging and, as a result, killed significantly more male than female A. makarovi. Our results show, for the first time, that arthropod predators can exploit prey vibrational communication to obtain information about prey availability and use this information to locate and capture prey. This may be a widespread mechanism for prey location, one that is likely to be a major unrecognized driver of evolution in both predators and prey. © 2011 Blackwell Publishing Ltd.

  7. Selective olfactory attention of a specialised predator to intraspecific chemical signals of its prey.

    Science.gov (United States)

    Cárdenas, Manuel; Jiroš, Pavel; Pekár, Stano

    2012-08-01

    Prey-specialised predators have evolved specific cognitive adaptations that increase their prey searching efficiency. In particular, when the prey is social, selection probably favours the use of prey intraspecific chemical signals by predatory arthropods. Using a specialised ant-eating zodariid spider, Zodarion rubidum, which is known to prey on several ant species and possesses capture and venom adaptations more effective on Formicinae ants, we tested its ability to recognise chemical cues produced by several ant species. Using an olfactometer, we tested the response of Z. rubidum towards air with chemical cues from six different ant species: Camponotus ligniperda, Lasius platythorax and Formica rufibarbis (all Formicinae); and Messor structor, Myrmica scabrinodis and Tetramorium caespitum (all Myrmicinae). Z. rubidum was attracted to air carrying chemical cues only from F. rufibarbis and L. platythorax. Then, we identified that the spiders were attracted to airborne cues coming from the F. rufibarbis gaster and Dufour's gland, in particular. Finally, we found that among several synthetic blends, the decyl acetate and undecane mixture produced significant attraction of spiders. These chemicals are produced only by three Formicine genera. Furthermore, we investigated the role of these chemical cues in the communication of F. rufibarbis and found that this blend reduces their movement. This study demonstrates the chemical cognitive capacity of Z. rubidum to locate its ant prey using chemical signals produced by the ants. The innate capacity of Z. rubidum to olfactory detect different ant species is narrow, as it includes only two ant genera, confirming trophic specialisation at lower than subfamily level. The olfactory cue detected by Zodarion spiders is probably a component of the recruitment or trail pheromone.

  8. Owls may use faeces and prey feathers to signal current reproduction.

    Directory of Open Access Journals (Sweden)

    Vincenzo Penteriani

    Full Text Available BACKGROUND: Many animals communicate by marking focal elements of their home range with different kinds of materials. Visual signaling has been demonstrated to play a previously unrecognized role in the intraspecific communication of eagle owls (Bubo bubo, in both territorial and parent-offspring contexts. Visual signals may play a role in a variety of circumstances in this crepuscular and nocturnal species. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report that a large amount of extremely visible white faeces and prey feathers appear during the breeding season on posts and plucking sites in proximity to the nest, potentially representing a way for eagle owls to mark their territory. We present descriptive and experimental evidence showing that faeces and prey remains could act as previously unrecognized visual signals in a nocturnal avian predator. This novel signaling behavior could indicate the owls' current reproductive status to potential intruders, such as other territorial owls or non-breeding floaters. Faeces and prey feather markings may also advertise an owl's reproductive status or function in mate-mate communication. CONCLUSIONS/SIGNIFICANCE: We speculate that faeces marks and plucking may represent an overlooked but widespread method for communicating current reproduction to conspecifics. Such marking behavior may be common in birds, and we may now be exploring other questions and mechanisms in territoriality.

  9. Owls may use faeces and prey feathers to signal current reproduction.

    Science.gov (United States)

    Penteriani, Vincenzo; Delgado, Maria del Mar

    2008-08-20

    Many animals communicate by marking focal elements of their home range with different kinds of materials. Visual signaling has been demonstrated to play a previously unrecognized role in the intraspecific communication of eagle owls (Bubo bubo), in both territorial and parent-offspring contexts. Visual signals may play a role in a variety of circumstances in this crepuscular and nocturnal species. Here, we report that a large amount of extremely visible white faeces and prey feathers appear during the breeding season on posts and plucking sites in proximity to the nest, potentially representing a way for eagle owls to mark their territory. We present descriptive and experimental evidence showing that faeces and prey remains could act as previously unrecognized visual signals in a nocturnal avian predator. This novel signaling behavior could indicate the owls' current reproductive status to potential intruders, such as other territorial owls or non-breeding floaters. Faeces and prey feather markings may also advertise an owl's reproductive status or function in mate-mate communication. We speculate that faeces marks and plucking may represent an overlooked but widespread method for communicating current reproduction to conspecifics. Such marking behavior may be common in birds, and we may now be exploring other questions and mechanisms in territoriality.

  10. Prey-capture success revealed by echolocation signals in pipistrelle bats (Pipistrellus pygmaeus)

    DEFF Research Database (Denmark)

    Surlykke, Annemarie; Futtrup, Vibeke; Tougaard, Jakob

    2003-01-01

    Three Pipistrellus pygmaeus bats were trained to capture prey on the wing while flying in the laboratory. The bats' capture behaviour and capture success were determined and correlated with acoustic analyses of post-buzz echolocation signals. Three acoustic parameters revealed capture success: in...

  11. A Novel Approach of Sensitive Infrared Signal Detection for Space Applications

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop an innovative frequency up-conversion device that will efficiently convert the infrared signals into visible/near-infrared signals to enable detection of...

  12. Algorithm for removing scalp signals from functional near-infrared spectroscopy signals in real time using multidistance optodes.

    Science.gov (United States)

    Kiguchi, Masashi; Funane, Tsukasa

    2014-11-01

    A real-time algorithm for removing scalp-blood signals from functional near-infrared spectroscopy signals is proposed. Scalp and deep signals have different dependencies on the source-detector distance. These signals were separated using this characteristic. The algorithm was validated through an experiment using a dynamic phantom in which shallow and deep absorptions were independently changed. The algorithm for measurement of oxygenated and deoxygenated hemoglobins using two wavelengths was explicitly obtained. This algorithm is potentially useful for real-time systems, e.g., brain-computer interfaces and neuro-feedback systems.

  13. Modeling of the shape of infrared stimulated luminescence signals in feldspars

    DEFF Research Database (Denmark)

    Pagonis, Vasilis; Jain, Mayank; Murray, Andrew S.

    2012-01-01

    This paper presents a new empirical model describing infrared (IR) stimulation phenomena in feldspars. In the model electrons from the ground state of an electron trap are raised by infrared optical stimulation to the excited state, and subsequently recombine with a nearest-neighbor hole via...... corresponds to a fast rate of recombination processes taking place along the infrared stimulated luminescence (IRSL) curves. The subsequent decay of the simulated IRSL signal is characterized by a much slower recombination rate, which can be described by a power-law type of equation.Several simulations...

  14. The role of electrical and jasmonate signalling in the recognition of captured prey in the carnivorous sundew plant Drosera capensis

    Czech Academy of Sciences Publication Activity Database

    Krausko, M.; Perůtka, M.; Šebela, M.; Šamajová, O.; Šamaj, J.; Novák, Ondřej; Pavlovič, A.

    2017-01-01

    Roč. 213, č. 4 (2017), s. 1818-1835 ISSN 0028-646X R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : action potential * carnivorous plant * Drosera * electrical signal * enzymes * jasmonates * long-distance signalling * sundew Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Plant sciences, botany Impact factor: 7.330, year: 2016

  15. EMD-Based Symbolic Dynamic Analysis for the Recognition of Human and Nonhuman Pyroelectric Infrared Signals

    Directory of Open Access Journals (Sweden)

    Jiaduo Zhao

    2016-01-01

    Full Text Available In this paper, we propose an effective human and nonhuman pyroelectric infrared (PIR signal recognition method to reduce PIR detector false alarms. First, using the mathematical model of the PIR detector, we analyze the physical characteristics of the human and nonhuman PIR signals; second, based on the analysis results, we propose an empirical mode decomposition (EMD-based symbolic dynamic analysis method for the recognition of human and nonhuman PIR signals. In the proposed method, first, we extract the detailed features of a PIR signal into five symbol sequences using an EMD-based symbolization method, then, we generate five feature descriptors for each PIR signal through constructing five probabilistic finite state automata with the symbol sequences. Finally, we use a weighted voting classification strategy to classify the PIR signals with their feature descriptors. Comparative experiments show that the proposed method can effectively classify the human and nonhuman PIR signals and reduce PIR detector’s false alarms.

  16. EMD-Based Symbolic Dynamic Analysis for the Recognition of Human and Nonhuman Pyroelectric Infrared Signals.

    Science.gov (United States)

    Zhao, Jiaduo; Gong, Weiguo; Tang, Yuzhen; Li, Weihong

    2016-01-20

    In this paper, we propose an effective human and nonhuman pyroelectric infrared (PIR) signal recognition method to reduce PIR detector false alarms. First, using the mathematical model of the PIR detector, we analyze the physical characteristics of the human and nonhuman PIR signals; second, based on the analysis results, we propose an empirical mode decomposition (EMD)-based symbolic dynamic analysis method for the recognition of human and nonhuman PIR signals. In the proposed method, first, we extract the detailed features of a PIR signal into five symbol sequences using an EMD-based symbolization method, then, we generate five feature descriptors for each PIR signal through constructing five probabilistic finite state automata with the symbol sequences. Finally, we use a weighted voting classification strategy to classify the PIR signals with their feature descriptors. Comparative experiments show that the proposed method can effectively classify the human and nonhuman PIR signals and reduce PIR detector's false alarms.

  17. Preheat-induced signal enhancement in the infrared stimulated luminescence of young and bleached sediment samples

    International Nuclear Information System (INIS)

    Richardson, C.A.

    2000-01-01

    Natural and laboratory bleached surface and young samples of potassium feldspar sand separates and polymineral silt had their infrared stimulated luminescence (IRSL) signal measured before and after preheating at 220 deg. C for 10 min or 160 deg. C for 16 h. For both preheats, the laboratory bleached sand samples underwent a signal enhancement which was stable with laboratory storage. The youngest samples also showed natural signal enhancement. The silt sample showed no recuperation of bleached signal on preheating, but some in the natural signal. A range of filtered bleaches was applied to one surface sand sample. Signal levels before and after preheating were reduced by filtering out the UV from the bleaching spectrum. The unfiltered bleach, however, most closely reproduced the behaviour of the natural sample

  18. EXPERIMENTAL SETUP FOR THE STUDY OF INFRARED SIGNALS OF DIFFERENT SOIL MOISTURE

    Directory of Open Access Journals (Sweden)

    A. N. Popov

    2013-01-01

    Full Text Available The article presents: structural scheme of the installation for measuring the infrared radiation of the soil in the range of 6-14 um; technical characteristics device ИКВП-01. The opportunities of use of pyroelectric sensors type MLX90614ESF were researched. Dependence of the temperature of soil from its humidity and dependence of the signal IR instrument of soil temperature and humidity are presented.

  19. Estimating the marine signal in the near infrared for atmospheric correction of satellite ocean-color imagery over turbid waters

    Science.gov (United States)

    Bourdet, Alice; Frouin, Robert J.

    2014-11-01

    The classic atmospheric correction algorithm, routinely applied to second-generation ocean-color sensors such as SeaWiFS, MODIS, and MERIS, consists of (i) estimating the aerosol reflectance in the red and near infrared (NIR) where the ocean is considered black (i.e., totally absorbing), and (ii) extrapolating the estimated aerosol reflectance to shorter wavelengths. The marine reflectance is then retrieved by subtraction. Variants and improvements have been made over the years to deal with non-null reflectance in the red and near infrared, a general situation in estuaries and the coastal zone, but the solutions proposed so far still suffer some limitations, due to uncertainties in marine reflectance modeling in the near infrared or difficulty to extrapolate the aerosol signal to the blue when using observations in the shortwave infrared (SWIR), a spectral range far from the ocean-color wavelengths. To estimate the marine signal (i.e., the product of marine reflectance and atmospheric transmittance) in the near infrared, the proposed approach is to decompose the aerosol reflectance in the near infrared to shortwave infrared into principal components. Since aerosol scattering is smooth spectrally, a few components are generally sufficient to represent the perturbing signal, i.e., the aerosol reflectance in the near infrared can be determined from measurements in the shortwave infrared where the ocean is black. This gives access to the marine signal in the near infrared, which can then be used in the classic atmospheric correction algorithm. The methodology is evaluated theoretically from simulations of the top-of-atmosphere reflectance for a wide range of geophysical conditions and angular geometries and applied to actual MODIS imagery acquired over the Gulf of Mexico. The number of discarded pixels is reduced by over 80% using the PC modeling to determine the marine signal in the near infrared prior to applying the classic atmospheric correction algorithm.

  20. Feeding rates in the chaetognath Sagitta elegans : effects of prey size, prey swimming behaviour and small-scale turbulence

    DEFF Research Database (Denmark)

    Saito, H.; Kiørboe, Thomas

    2001-01-01

    distances. We develop a simple prey encounter rate model by describing the swimming prey as a 'force dipole' and assuming that a critical signal strength is required to elicit an attack. By fitting the model to the observations, a critical signal strength of 10(-2) cm s(-1) is estimated; this is very...... at rates up to an order of magnitude higher than similarly sized females, probably owing to differences in swimming behaviour. Sagitta elegans is an ambush predator that perceives its prey by hydromechanical signals. Faster swimming prey generates stronger signals and is, hence, perceived at longer...

  1. Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

    Directory of Open Access Journals (Sweden)

    S. Schweitzer

    2011-10-01

    Full Text Available LEO-LEO infrared-laser occultation (LIO is a new occultation technique between Low Earth Orbit (LEO satellites, which applies signals in the short wave infrared spectral range (SWIR within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We

  2. Application of near-infrared spectroscopy to measurement of hemodynamic signals accompanying stimulated saliva secretion.

    Science.gov (United States)

    Sato, Hiroki; Obata, Akiko N; Moda, Ichiro; Ozaki, Kazutaka; Yasuhara, Takaomi; Yamamoto, Yukari; Kiguchi, Masashi; Maki, Atsushi; Kubota, Kisou; Koizumi, Hideaki

    2011-04-01

    We aim to test the feasibility of using near-infrared spectroscopy (NIRS) for indirect measurement of human saliva secretion in response to taste stimuli for potential application to organoleptic testing. We use an NIRS system to measure extracranial hemodynamics (Hb-signals around the temples) of healthy participants when taste stimuli are taken in their mouths. First, the Hb-signals and volume of expelled saliva (stimulated by distilled-water or sucrose-solution intake) are simultaneously measured and large Hb-signal changes in response to the taste stimuli (Hb-responses) are found. Statistical analysis show that both the Hb response and saliva volume are larger for the sucrose solution than for the distilled water with a significant correlation between them (r = 0.81). The effects of swallowing on the Hb-signals are investigated. Similar Hb responses, differing from the sucrose solution and distilled water, are obtained even though the participants swallow the mouth contents. Finally, functional magnetic resonance imaging is used to identify possible sources of the Hb signals corresponding to salivation. Statistical analysis indicates similar responses in the extracranial regions, mainly around the middle meningeal artery. In conclusion, the identified correlation between extracranial hemodynamics and the saliva volume suggests that NIRS is applicable to the measurement of hemodynamic signals accompanying stimulated saliva secretion.

  3. Mathematical characterization of continuous wave infrared stimulated luminescence signals (CW-IRSL) from feldspars

    International Nuclear Information System (INIS)

    Pagonis, V.; Phan, Huy; Goodnow, Rebecca; Rosenfeld, Sara; Morthekai, P.

    2014-01-01

    Continuous-wave infrared stimulated luminescence signals (CW-IRSL) from feldspars have been the subject of many experimental studies, due to their importance in luminescence dating and dosimetry. Accurate mathematical characterization of the shape of these CW-IRSL signals in feldspars is of practical and theoretical importance, especially in connection with “anomalous fading” of luminescence signals in dating studies. These signals are known to decay in a non-exponential manner and their exact mathematical shape as a function of stimulation time is an open research question. At long stimulation times the IRSL decay has been shown experimentally to follow a power law of decay, and previous researchers have attempted to fit the overall shape of these signals empirically using the well known Becquerel function (or compressed hyperbola decay law). This paper investigates the possibility of fitting CW-IRSL curves using either the Becquerel decay law, or a recently developed analytical equation based on localized electronic recombination of donor–acceptor pairs in luminescent materials. It is shown that both mathematical approaches can give excellent fits to experimental CW-IRSL curves, and the precision of the fitting process is studied by analyzing a series of curves measured using a single aliquot of a feldspar sample. Both fitting equations are solutions of differential equations involving numerically similar time dependent recombination probabilities k(t). It is concluded that both fitting equations provide approximately equivalent mathematical descriptions of the CW-IRSL curves in feldspars, and can be used as mathematical representations of the shape of CW-IRSL signals. - Highlights: • Feldspar CW-IRSL curves fitted using Becquerel decay law and new analytical equation. • Both mathematical approaches give excellent fits to experimental CW-IRSL curves. • Series of experimental CW-IRSL curves analyzed using both fitting expressions. • The time

  4. Infrared

    Science.gov (United States)

    Vollmer, M.

    2013-11-01

    'Infrared' is a very wide field in physics and the natural sciences which has evolved enormously in recent decades. It all started in 1800 with Friedrich Wilhelm Herschel's discovery of infrared (IR) radiation within the spectrum of the Sun. Thereafter a few important milestones towards widespread use of IR were the quantitative description of the laws of blackbody radiation by Max Planck in 1900; the application of quantum mechanics to understand the rotational-vibrational spectra of molecules starting in the first half of the 20th century; and the revolution in source and detector technologies due to micro-technological breakthroughs towards the end of the 20th century. This has led to much high-quality and sophisticated equipment in terms of detectors, sources and instruments in the IR spectral range, with a multitude of different applications in science and technology. This special issue tries to focus on a few aspects of the astonishing variety of different disciplines, techniques and applications concerning the general topic of infrared radiation. Part of the content is based upon an interdisciplinary international conference on the topic held in 2012 in Bad Honnef, Germany. It is hoped that the information provided here may be useful for teaching the general topic of electromagnetic radiation in the IR spectral range in advanced university courses for postgraduate students. In the most general terms, the infrared spectral range is defined to extend from wavelengths of 780 nm (upper range of the VIS spectral range) up to wavelengths of 1 mm (lower end of the microwave range). Various definitions of near, middle and far infrared or thermal infrared, and lately terahertz frequencies, are used, which all fall in this range. These special definitions often depend on the scientific field of research. Unfortunately, many of these fields seem to have developed independently from neighbouring disciplines, although they deal with very similar topics in respect of the

  5. Parasites as prey

    NARCIS (Netherlands)

    Goedknegt, M.A.; Welsh, J.E.; Thieltges, D.W.

    2012-01-01

    Parasites are usually considered to use their hosts as a resource for energy. However, there is increasing awareness that parasites can also become a resource themselves and serve as prey for other organisms. Here we describe various types of predation in which parasites act as prey for other

  6. Far infrared promotes wound healing through activation of Notch1 signaling.

    Science.gov (United States)

    Hsu, Yung-Ho; Lin, Yuan-Feng; Chen, Cheng-Hsien; Chiu, Yu-Jhe; Chiu, Hui-Wen

    2017-11-01

    The Notch signaling pathway is critically involved in cell proliferation, differentiation, development, and homeostasis. Far infrared (FIR) has an effect that promotes wound healing. However, the underlying molecular mechanisms are unclear. In the present study, we employed in vivo and HaCaT (a human skin keratinocyte cell line) models to elucidate the role of Notch1 signaling in FIR-promoted wound healing. We found that FIR enhanced keratinocyte migration and proliferation. FIR induced the Notch1 signaling pathway in HaCaT cells and in a microarray dataset from the Gene Expression Omnibus database. We next determined the mRNA levels of NOTCH1 in paired normal and wound skin tissues derived from clinical patients using the microarray dataset and Ingenuity Pathway Analysis software. The result indicated that the Notch1/Twist1 axis plays important roles in wound healing and tissue repair. In addition, inhibiting Notch1 signaling decreased the FIR-enhanced proliferation and migration. In a full-thickness wound model in rats, the wounds healed more rapidly and the scar size was smaller in the FIR group than in the light group. Moreover, FIR could increase Notch1 and Delta1 in skin tissues. The activation of Notch1 signaling may be considered as a possible mechanism for the promoting effect of FIR on wound healing. FIR stimulates keratinocyte migration and proliferation. Notch1 in keratinocytes has an essential role in FIR-induced migration and proliferation. NOTCH1 promotes TWIST1-mediated gene expression to assist wound healing. FIR might promote skin wound healing in a rat model. FIR stimulates keratinocyte migration and proliferation. Notch1 in keratinocytes has an essential role in FIR-induced migration and proliferation. NOTCH1 promotes TWIST1-mediated gene expression to assist wound healing. FIR might promote skin wound healing in a rat model.

  7. Decomposition of Near-Infrared Spectroscopy Signals Using Oblique Subspace Projections: Applications in Brain Hemodynamic Monitoring

    Directory of Open Access Journals (Sweden)

    Alexander Caicedo

    2016-11-01

    Full Text Available Clinical data is comprised by a large number of synchronously collected biomedical signals that are measured at different locations. Deciphering the interrelationships of these signals can yield important information about their dependence providing some useful clinical diagnostic data. For instance, by computing the coupling between Near-Infrared Spectroscopy signals (NIRS and systemic variables the status of the hemodynamic regulation mechanisms can be assessed. In this paper we introduce an algorithm for the decomposition of NIRS signals into additive components. The algorithm, SIgnal DEcomposition base on Obliques Subspace Projections (SIDE-ObSP, assumes that the measured NIRS signal is a linear combination of the systemic measurements, following the linear regression model y = Ax + _. SIDE-ObSP decomposes the output such that, each component in the decomposition represents the sole linear influence of one corresponding regressor variable. This decomposition scheme aims at providing a better understanding of the relation between NIRS and systemic variables, and to provide a framework for the clinical interpretation of regression algorithms, thereby, facilitating their introduction into clinical practice. SIDE-ObSP combines oblique subspace projections (ObSP with the structure of a mean average system in order to define adequate signal subspaces. To guarantee smoothness in the estimated regression parameters, as observed in normal physiological processes, we impose a Tikhonov regularization using a matrix differential operator. We evaluate the performance of SIDE-ObSP by using a synthetic dataset, and present two case studies in the field of cerebral hemodynamics monitoring using NIRS. In addition, we compare the performance of this method with other system identification techniques. In the first case study data from 20 neonates during the first three days of life was used, here SIDE-ObSP decoupled the influence of changes in arterial oxygen

  8. Decomposition of Near-Infrared Spectroscopy Signals Using Oblique Subspace Projections: Applications in Brain Hemodynamic Monitoring.

    Science.gov (United States)

    Caicedo, Alexander; Varon, Carolina; Hunyadi, Borbala; Papademetriou, Maria; Tachtsidis, Ilias; Van Huffel, Sabine

    2016-01-01

    Clinical data is comprised by a large number of synchronously collected biomedical signals that are measured at different locations. Deciphering the interrelationships of these signals can yield important information about their dependence providing some useful clinical diagnostic data. For instance, by computing the coupling between Near-Infrared Spectroscopy signals (NIRS) and systemic variables the status of the hemodynamic regulation mechanisms can be assessed. In this paper we introduce an algorithm for the decomposition of NIRS signals into additive components. The algorithm, SIgnal DEcomposition base on Obliques Subspace Projections (SIDE-ObSP), assumes that the measured NIRS signal is a linear combination of the systemic measurements, following the linear regression model y = Ax + ϵ . SIDE-ObSP decomposes the output such that, each component in the decomposition represents the sole linear influence of one corresponding regressor variable. This decomposition scheme aims at providing a better understanding of the relation between NIRS and systemic variables, and to provide a framework for the clinical interpretation of regression algorithms, thereby, facilitating their introduction into clinical practice. SIDE-ObSP combines oblique subspace projections (ObSP) with the structure of a mean average system in order to define adequate signal subspaces. To guarantee smoothness in the estimated regression parameters, as observed in normal physiological processes, we impose a Tikhonov regularization using a matrix differential operator. We evaluate the performance of SIDE-ObSP by using a synthetic dataset, and present two case studies in the field of cerebral hemodynamics monitoring using NIRS. In addition, we compare the performance of this method with other system identification techniques. In the first case study data from 20 neonates during the first 3 days of life was used, here SIDE-ObSP decoupled the influence of changes in arterial oxygen saturation from the

  9. Prey detection and prey capture in copepod nauplii

    DEFF Research Database (Denmark)

    Bruno, Eleonora; Borg, Marc Andersen; Kiørboe, Thomas

    2012-01-01

    Copepod nauplii are either ambush feeders that feed on motile prey or they produce a feeding current that entrains prey cells. It is unclear how ambush and feeding-current feeding nauplii perceive and capture prey. Attack jumps in ambush feeding nauplii should not be feasible at low Reynolds...... (Temora longicornis). We demonstrate that the ambush feeders both detect motile prey remotely. Prey detection elicits an attack jump, but the jump is not directly towards the prey, such as has been described for adult copepods. Rather, the nauplius jumps past the prey and sets up an intermittent feeding...

  10. Prey detection and prey capture in copepod nauplii.

    Directory of Open Access Journals (Sweden)

    Eleonora Bruno

    Full Text Available Copepod nauplii are either ambush feeders that feed on motile prey or they produce a feeding current that entrains prey cells. It is unclear how ambush and feeding-current feeding nauplii perceive and capture prey. Attack jumps in ambush feeding nauplii should not be feasible at low Reynolds numbers due to the thick viscous boundary layer surrounding the attacking nauplius. We use high-speed video to describe the detection and capture of phytoplankton prey by the nauplii of two ambush feeding species (Acartia tonsa and Oithona davisae and by the nauplii of one feeding-current feeding species (Temora longicornis. We demonstrate that the ambush feeders both detect motile prey remotely. Prey detection elicits an attack jump, but the jump is not directly towards the prey, such as has been described for adult copepods. Rather, the nauplius jumps past the prey and sets up an intermittent feeding current that pulls in the prey from behind towards the mouth. The feeding-current feeding nauplius detects prey arriving in the feeding current but only when the prey is intercepted by the setae on the feeding appendages. This elicits an altered motion pattern of the feeding appendages that draws in the prey.

  11. A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner, E-mail: maentele@biophysik.uni-frankfurt.de [Institut für Biophysik, Goethe-Universität Frankfurt am Main, Max-von Laue-Straße 1, D-60438 Frankfurt am Main (Germany)

    2014-08-15

    A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

  12. A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

    Science.gov (United States)

    Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner

    2014-08-01

    A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

  13. Improved signal to noise ratio and sensitivity of an infrared imaging video bolometer on large helical device by using an infrared periscope

    International Nuclear Information System (INIS)

    Pandya, Shwetang N.; Sano, Ryuichi; Peterson, Byron J.; Mukai, Kiyofumi; Enokuchi, Akito; Takeyama, Norihide

    2014-01-01

    An Infrared imaging Video Bolometer (IRVB) diagnostic is currently being used in the Large Helical Device (LHD) for studying the localization of radiation structures near the magnetic island and helical divertor X-points during plasma detachment and for 3D tomography. This research demands high signal to noise ratio (SNR) and sensitivity to improve the temporal resolution for studying the evolution of radiation structures during plasma detachment and a wide IRVB field of view (FoV) for tomography. Introduction of an infrared periscope allows achievement of a higher SNR and higher sensitivity, which in turn, permits a twofold improvement in the temporal resolution of the diagnostic. Higher SNR along with wide FoV is achieved simultaneously by reducing the separation of the IRVB detector (metal foil) from the bolometer's aperture and the LHD plasma. Altering the distances to meet the aforesaid requirements results in an increased separation between the foil and the IR camera. This leads to a degradation of the diagnostic performance in terms of its sensitivity by 1.5-fold. Using an infrared periscope to image the IRVB foil results in a 7.5-fold increase in the number of IR camera pixels imaging the foil. This improves the IRVB sensitivity which depends on the square root of the number of IR camera pixels being averaged per bolometer channel. Despite the slower f-number (f/# = 1.35) and reduced transmission (τ 0 = 89%, due to an increased number of lens elements) for the periscope, the diagnostic with an infrared periscope operational on LHD has improved in terms of sensitivity and SNR by a factor of 1.4 and 4.5, respectively, as compared to the original diagnostic without a periscope (i.e., IRVB foil being directly imaged by the IR camera through conventional optics). The bolometer's field of view has also increased by two times. The paper discusses these improvements in apt details

  14. Validation of brain-derived signals in near-infrared spectroscopy through multivoxel analysis of concurrent functional magnetic resonance imaging.

    Science.gov (United States)

    Moriguchi, Yoshiya; Noda, Takamasa; Nakayashiki, Kosei; Takata, Yohei; Setoyama, Shiori; Kawasaki, Shingo; Kunisato, Yoshihiko; Mishima, Kazuo; Nakagome, Kazuyuki; Hanakawa, Takashi

    2017-10-01

    Near-infrared spectroscopy (NIRS) is a convenient and safe brain-mapping tool. However, its inevitable confounding with hemodynamic responses outside the brain, especially in the frontotemporal head, has questioned its validity. Some researchers attempted to validate NIRS signals through concurrent measurements with functional magnetic resonance imaging (fMRI), but, counterintuitively, NIRS signals rarely correlate with local fMRI signals in NIRS channels, although both mapping techniques should measure the same hemoglobin concentration. Here, we tested a novel hypothesis that different voxels within the scalp and the brain tissues might have substantially different hemoglobin absorption rates of near-infrared light, which might differentially contribute to NIRS signals across channels. Therefore, we newly applied a multivariate approach, a partial least squares regression, to explain NIRS signals with multivoxel information from fMRI within the brain and soft tissues in the head. We concurrently obtained fMRI and NIRS signals in 9 healthy human subjects engaging in an n-back task. The multivariate fMRI model was quite successfully able to predict the NIRS signals by cross-validation (interclass correlation coefficient = ∼0.85). This result confirmed that fMRI and NIRS surely measure the same hemoglobin concentration. Additional application of Monte-Carlo permutation tests confirmed that the model surely reflects temporal and spatial hemodynamic information, not random noise. After this thorough validation, we calculated the ratios of the contributions of the brain and soft-tissue hemodynamics to the NIRS signals, and found that the contribution ratios were quite different across different NIRS channels in reality, presumably because of the structural complexity of the frontotemporal regions. Hum Brain Mapp 38:5274-5291, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  15. Extraction of fast neuronal changes from multichannel functional near-infrared spectroscopy signals using independent component analysis

    Science.gov (United States)

    Morren, Geert; Wolf, Martin; Lemmerling, Philippe; Wolf, Ursula; Choi, Jee H.; Gratton, Enrico; De Lathauwer, Lieven; Van Huffel, Sabine

    2002-06-01

    Fast changes in the range of milliseconds in the optical properties of cerebral tissue, which are associated with brain activity, can be detected using non-invasive near-infrared spectroscopy (NIRS). These changes in light scattering are due to an alteration in the refractive index at neuronal membranes. The aim of this study was to develop highly sensitive data analysis algorithms to detect this fast signal, which is small compared to other physiological signals. A frequency-domain tissue oximeter, whose laser diodes were modulated at 110MHz was used. The amplitude, mean intensity and phase of the modulated optical signal was measured at 96Hz sample rate. The probe consisting of 4 crossed source detector pairs was placed above the motor cortex, contralateral to the hand performing a tapping exercise consisting of alternating rest- and tapping periods of 20s each. The tapping frequency, which was set to 3.55Hz or 2.5 times the heart rate of the subject to avoid the influence of harmonics on the signal, could not be observed in any of the individual signals measured by the detectors. An adaptive filter was used to remove the arterial pulsatility from the optical signals. Independent Component Analysis allowed to separate signal components in which the tapping frequency was clearly visible.

  16. Perceptual advertisement by the prey of stalking or ambushing predators.

    Science.gov (United States)

    Broom, Mark; Ruxton, Graeme D

    2012-12-21

    There has been previous theoretical explorations of the stability of signals by prey that they have detected a stalking or ambush predator, where such perceptual advertisement dissuades the predator from attacking. Here we use a game theoretical model to extend the theory to consider some empirically-motivated complexities: (i) many perceptual advertisement signals appear to have the potential to vary in intensity, (ii) higher intensity signals are likely to be most costly to produce, and (iii) some high-cost signals (such as staring directly at the predator) can only be utilised if the prey is very confident of the existence of a nearby predator (that is, there are reserved or unfakable signals). We demonstrate that these complexities still allow for stable signalling. However, we do not find solutions where prey use a range of signal intensities to signal different degrees of confidence in the proximity of a predator; with prey simply adopting a binary response of not signalling or always signalling at the same fixed level. However this fixed level will not always be the cheapest possible signal, and we predict that prey that require more certainty about proximity of a predator will use higher-cost signals. The availability of reserved signals does not prohibit the stability of signalling based on lower-cost signals, but we also find circumstances where only the reserved signal is used. We discuss the potential to empirically test our model predictions, and to develop theory further to allow perceptual advertisement to be combined with other signalling functions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. The Allometry of Prey Preferences

    Science.gov (United States)

    Kalinkat, Gregor; Rall, Björn Christian; Vucic-Pestic, Olivera; Brose, Ulrich

    2011-01-01

    The distribution of weak and strong non-linear feeding interactions (i.e., functional responses) across the links of complex food webs is critically important for their stability. While empirical advances have unravelled constraints on single-prey functional responses, their validity in the context of complex food webs where most predators have multiple prey remain uncertain. In this study, we present conceptual evidence for the invalidity of strictly density-dependent consumption as the null model in multi-prey experiments. Instead, we employ two-prey functional responses parameterised with allometric scaling relationships of the functional response parameters that were derived from a previous single-prey functional response study as novel null models. Our experiments included predators of different sizes from two taxonomical groups (wolf spiders and ground beetles) simultaneously preying on one small and one large prey species. We define compliance with the null model predictions (based on two independent single-prey functional responses) as passive preferences or passive switching, and deviations from the null model as active preferences or active switching. Our results indicate active and passive preferences for the larger prey by predators that are at least twice the size of the larger prey. Moreover, our approach revealed that active preferences increased significantly with the predator-prey body-mass ratio. Together with prior allometric scaling relationships of functional response parameters, this preference allometry may allow estimating the distribution of functional response parameters across the myriads of interactions in natural ecosystems. PMID:21998724

  18. The allometry of prey preferences.

    Directory of Open Access Journals (Sweden)

    Gregor Kalinkat

    Full Text Available The distribution of weak and strong non-linear feeding interactions (i.e., functional responses across the links of complex food webs is critically important for their stability. While empirical advances have unravelled constraints on single-prey functional responses, their validity in the context of complex food webs where most predators have multiple prey remain uncertain. In this study, we present conceptual evidence for the invalidity of strictly density-dependent consumption as the null model in multi-prey experiments. Instead, we employ two-prey functional responses parameterised with allometric scaling relationships of the functional response parameters that were derived from a previous single-prey functional response study as novel null models. Our experiments included predators of different sizes from two taxonomical groups (wolf spiders and ground beetles simultaneously preying on one small and one large prey species. We define compliance with the null model predictions (based on two independent single-prey functional responses as passive preferences or passive switching, and deviations from the null model as active preferences or active switching. Our results indicate active and passive preferences for the larger prey by predators that are at least twice the size of the larger prey. Moreover, our approach revealed that active preferences increased significantly with the predator-prey body-mass ratio. Together with prior allometric scaling relationships of functional response parameters, this preference allometry may allow estimating the distribution of functional response parameters across the myriads of interactions in natural ecosystems.

  19. ANALYTICAL MODEL OF A DIFFERENTIAL METHOD FOR RECEIVING AND PROCESSING SIGNALS OF THE INFRARED RANGE OF WAVELENGTHS

    Directory of Open Access Journals (Sweden)

    N. S. Akinshin

    2017-01-01

    Full Text Available One of the classic methods to improve the noise immunity of passive detection of infrared wavelength range (IKSO is a differential inclusion of pyrocatechol, placed at some distance. An analytical model of a differential method of receiving infrared radiation from moving objects is introduced. A comparison with experimental results for moving objects of different types is made. Differential inclusion of sensors can be used not only to compensate the external interference, but also to determine the boundaries of a temporary "slot", inside which the movable object is most likely to be detected. The temporal boundaries are used for the decision making about the type and parameters of the movable object in complexional device of object classification.The principle of operation of ikso, which is to record signals with diversity of pyrocatechol into the appropriate memory registers and output detection of the differential signal envelope. Subsequently, from the memory registers portions of a recording signal posted pyrocatechol are selected which are later processed to determine the temporal provisions of minimum minimore and maximum maximore. The direction of movement of the object abeam is determined by the delay or advance of the extrema of the signals of one sensor relative to another within a given temporal "slot".It is shown that aggregation should be the following – the tool with a maximum radius of the zone of sensitivity should be active and the basic, but if there is a more reliable piece of information about the detected object which can implement a more refined classification of the object (for example, a group of people, wheeled vehicles-tracked vehicles, etc.. The conclusion is made about the advantages of differential option to include spaced sensors.The results can be used in the development of infrared wavelengths passive detection in the conceptual design phase.

  20. MOTION ARTIFACT REDUCTION IN FUNCTIONAL NEAR INFRARED SPECTROSCOPY SIGNALS BY AUTOREGRESSIVE MOVING AVERAGE MODELING BASED KALMAN FILTERING

    Directory of Open Access Journals (Sweden)

    MEHDI AMIAN

    2013-10-01

    Full Text Available Functional near infrared spectroscopy (fNIRS is a technique that is used for noninvasive measurement of the oxyhemoglobin (HbO2 and deoxyhemoglobin (HHb concentrations in the brain tissue. Since the ratio of the concentration of these two agents is correlated with the neuronal activity, fNIRS can be used for the monitoring and quantifying the cortical activity. The portability of fNIRS makes it a good candidate for studies involving subject's movement. The fNIRS measurements, however, are sensitive to artifacts generated by subject's head motion. This makes fNIRS signals less effective in such applications. In this paper, the autoregressive moving average (ARMA modeling of the fNIRS signal is proposed for state-space representation of the signal which is then fed to the Kalman filter for estimating the motionless signal from motion corrupted signal. Results are compared to the autoregressive model (AR based approach, which has been done previously, and show that the ARMA models outperform AR models. We attribute it to the richer structure, containing more terms indeed, of ARMA than AR. We show that the signal to noise ratio (SNR is about 2 dB higher for ARMA based method.

  1. Non-destructive testing of high heat flux components of fusion devices by infrared thermography: modeling and signal processing

    International Nuclear Information System (INIS)

    Cismondi, Fabio

    2007-01-01

    In Plasma Facing Components (PFCs) the joint of the CFC armour material onto the metallic CuCrZr heat sink needs to be significant defects free. Detection of material flaws is a major issue of the PFCs acceptance protocol. A Non-Destructive Technique (NDT) based upon active infrared thermography allows testing PFCs on SATIR tests bed in Cadarache. Up to now defect detection was based on the comparison of the surface temperature evolution of the inspected component with that of a supposed 'defect-free' one (used as a reference element). This work deals with improvement of thermal signal processing coming from SATIR. In particular the contributions of the thermal modelling and statistical signal processing converge in this work. As for thermal modelling, the identification of a sensitive parameter to defect presence allows improving the quantitative estimation of defect Otherwise Finite Element (FE) modeling of SATIR allows calculating the so called deterministic numerical tile. Statistical approach via the Monte Carlo technique extends the numerical tile concept to the numerical population concept. As for signal processing, traditional statistical treatments allow a better localization of the bond defect processing thermo-signal by itself, without utilising a reference signal. Moreover the problem of detection and classification of random signals can be solved by maximizing the signal-to-noise ratio. Two filters maximizing the signal-to-noise ratio are optimized: the stochastic matched filter aims at detects detection and the constrained stochastic matched filter aims at defects classification. Performances are quantified and methods are compared via the ROC curves. (author)

  2. Detecting infrared luminescence and non-chemical signaling of living cells: single cell mid-IR spectroscopy in cryogenic environments

    Science.gov (United States)

    Pereverzev, Sergey

    2017-02-01

    Many life-relevant interaction energies are in IR range, and it is reasonable to believe that some biochemical reactions inside cells can results in emission of IR photons. Cells can use this emission for non-chemical and non-electrical signaling. Detecting weak infrared radiation from live cells is complicated because of strong thermal radiation background and absorption of radiation by tissues. A microfluidic device with live cells inside a vacuum cryogenic environment should suppress this background, and thereby permit observation of live cell auto-luminescence or signaling in the IR regime. One can make IR-transparent windows not emitting in this range, so only the cell and a small amount of liquid around it will emit infrared radiation. Currently mid-IR spectroscopy of single cells requires the use of a synchrotron source to measure absorption or reflection spectra. Decreasing of thermal radiation background will allow absorption and reflection spectroscopy of cells without using synchrotron light. Moreover, cell auto-luminescence can be directly measured. The complete absence of thermal background radiation for cryogenically cooled samples allows the use IR photon-sensitive detectors and obtaining single molecule sensitivity in IR photo-luminescence measurements. Due to low photon energies, photo-luminescence measurements will be non-distractive for pressures samples. The technique described here is based upon US patent 9366574.

  3. Do radio frequencies of medical instruments common in the operating room interfere with near-infrared spectroscopy signals?

    Science.gov (United States)

    Shadgan, Babak; Molavi, Behnam; Reid, W. D.; Dumont, Guy; Macnab, Andrew J.

    2010-02-01

    Background: Medical and diagnostic applications of near infrared spectroscopy (NIRS) are increasing, especially in operating rooms (OR). Since NIRS is an optical technique, radio frequency (RF) interference from other instruments is unlikely to affect the raw optical data, however, NIRS data processing and signal output could be affected. Methods: We investigated the potential for three common OR instruments: an electrical cautery, an orthopaedic drill and an imaging system, to generate electromagnetic interference (EMI) that could potentially influence NIRS signals. The time of onset and duration of every operation of each device was recorded during surgery. To remove the effects of slow changing physiological variables, we first used a lowpass filter and then selected 2 windows with variable lengths around the moment of device onset. For each instant, variances (energy) and means of the signals in the 2 windows were compared. Results: Twenty patients were studied during ankle surgery. Analysis shows no statistically significant difference in the means and variance of the NIRS signals (p < 0.01) during operation of any of the three devices for all surgeries. Conclusion: This method confirms the instruments evaluated caused no significant interference. NIRS can potentially be used without EMI in clinical environments such as the OR.

  4. The extent of unwanted infrared photoacoustic signals from polymer sampling tubings exposed to ultraviolet radiation

    NARCIS (Netherlands)

    Bicanic, D.; Solyom, A.; Angeli, G.; Wegh, H.; Postumus, M.; Jalink, H.

    1995-01-01

    The extent of unwanted photoacoustic (PA) signals due to volatiles released from various polymer tubing materials [transparent, red and black polyethylene (PE), polymer of tetrafluorethylene (PTFE) and copolymer of tetrafluorethylene and hexafluorethylene (FEP)] when exposed to 245 nm radiation was

  5. Processing Functional Near Infrared Spectroscopy Signal with a Kalman Filter to Assess Working Memory during Simulated Flight.

    Science.gov (United States)

    Durantin, Gautier; Scannella, Sébastien; Gateau, Thibault; Delorme, Arnaud; Dehais, Frédéric

    2015-01-01

    Working memory (WM) is a key executive function for operating aircraft, especially when pilots have to recall series of air traffic control instructions. There is a need to implement tools to monitor WM as its limitation may jeopardize flight safety. An innovative way to address this issue is to adopt a Neuroergonomics approach that merges knowledge and methods from Human Factors, System Engineering, and Neuroscience. A challenge of great importance for Neuroergonomics is to implement efficient brain imaging techniques to measure the brain at work and to design Brain Computer Interfaces (BCI). We used functional near infrared spectroscopy as it has been already successfully tested to measure WM capacity in complex environment with air traffic controllers (ATC), pilots, or unmanned vehicle operators. However, the extraction of relevant features from the raw signal in ecological environment is still a critical issue due to the complexity of implementing real-time signal processing techniques without a priori knowledge. We proposed to implement the Kalman filtering approach, a signal processing technique that is efficient when the dynamics of the signal can be modeled. We based our approach on the Boynton model of hemodynamic response. We conducted a first experiment with nine participants involving a basic WM task to estimate the noise covariances of the Kalman filter. We then conducted a more ecological experiment in our flight simulator with 18 pilots who interacted with ATC instructions (two levels of difficulty). The data was processed with the same Kalman filter settings implemented in the first experiment. This filter was benchmarked with a classical pass-band IIR filter and a Moving Average Convergence Divergence (MACD) filter. Statistical analysis revealed that the Kalman filter was the most efficient to separate the two levels of load, by increasing the observed effect size in prefrontal areas involved in WM. In addition, the use of a Kalman filter increased

  6. Processing Functional Near Infrared Spectroscopy Signal with a Kalman Filter to Assess Working Memory during Simulated Flight.

    Directory of Open Access Journals (Sweden)

    Gautier eDurantin

    2016-01-01

    Full Text Available Working memory is a key executive function for operating aircraft, especially when pilots have to recall series of air traffic control instructions. There is a need to implement tools to monitor working memory as its limitation may jeopardize flight safety. An innovative way to address this issue is to adopt a Neuroergonomics approach that merges knowledge and methods from Human Factors, System Engineering and Neuroscience. A challenge of great importance for Neuroergonomics is to implement efficient brain imaging techniques to measure the brain at work and to design Brain Computer Interfaces. We used functional near infrared spectroscopy as it has been already successfully tested to measure working memory capacity in complex environment with air traffic controllers, pilots or unmanned vehicle operators. However, the extraction of relevant features from the raw signal in ecological environment is still a critical issue due to the complexity of implementing real-time signal processing techniques without a priori knowledge. We proposed to implement the Kalman filtering approach, a signal processing technique that is efficient when the dynamics of the signal can be modeled. We based our approach on the Boynton model of hemodynamic response. We conducted a first experiment with 9 participants involving a basic working memory task to estimate the noise covariances of the Kalman filter. We then conducted a more ecological experiment in our flight simulator with 18 pilots who interacted with air traffic controller instructions (two levels of difficulty. The data was processed with the same Kalman filter settings implemented in the first experiment. This filter was benchmarked with a classical pass-band IIR filter and a Moving Average Convergence Divergence filter. Statistical analysis revealed that the Kalman filter was the most efficient to separate the two levels of load, by increasing the observed effect size in prefrontal areas involved in working

  7. Time-resolved infrared stimulated luminescence signals in feldspars: Analysis based on exponential and stretched exponential functions

    International Nuclear Information System (INIS)

    Pagonis, V.; Morthekai, P.; Singhvi, A.K.; Thomas, J.; Balaram, V.; Kitis, G.; Chen, R.

    2012-01-01

    Time-resolved infrared-stimulated luminescence (TR-IRSL) signals from feldspar samples have been the subject of several recent experimental studies. These signals are of importance in the field of luminescence dating, since they exhibit smaller fading effects than the commonly employed continuous-wave infrared signals (CW-IRSL). This paper presents a semi-empirical analysis of TR-IRSL data from feldspar samples, by using a linear combination of exponential and stretched exponential (SE) functions. The best possible estimates of the five parameters in this semi-empirical approach are obtained using five popular commercially available software packages, and by employing a variety of global optimization techniques. The results from all types of software and from the different fitting algorithms were found to be in close agreement with each other, indicating that a global optimum solution has likely been reached during the fitting process. Four complete sets of TR-IRSL data on well-characterized natural feldspars were fitted by using such a linear combination of exponential and SE functions. The dependence of the extracted fitting parameters on the stimulation temperature is discussed within the context of a recently proposed model of luminescence processes in feldspar. Three of the four feldspar samples studied in this paper are K-rich, and these exhibited different behavior at higher stimulation temperatures, than the fourth sample which was a Na-rich feldspar. The new method of analysis proposed in this paper can help isolate mathematically the more thermally stable components, and hence could lead to better dating applications in these materials. - Highlights: ► TR-IRSL from four feldspars were analyzed using exponential and stretched exponential functions. ► A variety of global optimization techniques give good agreement. ► Na-rich sample behavior is different from the three K-rich samples. ► Experimental data are fitted for stimulation temperatures

  8. Autofluorescence Imaging With Near-Infrared Excitation:Normalization by Reflectance to Reduce Signal From Choroidal Fluorophores

    Science.gov (United States)

    Cideciyan, Artur V.; Swider, Malgorzata; Jacobson, Samuel G.

    2015-01-01

    Purpose. We previously developed reduced-illuminance autofluorescence imaging (RAFI) methods involving near-infrared (NIR) excitation to image melanin-based fluorophores and short-wavelength (SW) excitation to image lipofuscin-based flurophores. Here, we propose to normalize NIR-RAFI in order to increase the relative contribution of retinal pigment epithelium (RPE) fluorophores. Methods. Retinal imaging was performed with a standard protocol holding system parameters invariant in healthy subjects and in patients. Normalized NIR-RAFI was derived by dividing NIR-RAFI signal by NIR reflectance point-by-point after image registration. Results. Regions of RPE atrophy in Stargardt disease, AMD, retinitis pigmentosa, choroideremia, and Leber congenital amaurosis as defined by low signal on SW-RAFI could correspond to a wide range of signal on NIR-RAFI depending on the contribution from the choroidal component. Retinal pigment epithelium atrophy tended to always correspond to high signal on NIR reflectance. Normalizing NIR-RAFI reduced the choroidal component of the signal in regions of atrophy. Quantitative evaluation of RPE atrophy area showed no significant differences between SW-RAFI and normalized NIR-RAFI. Conclusions. Imaging of RPE atrophy using lipofuscin-based AF imaging has become the gold standard. However, this technique involves bright SW lights that are uncomfortable and may accelerate the rate of disease progression in vulnerable retinas. The NIR-RAFI method developed here is a melanin-based alternative that is not absorbed by opsins and bisretinoid moieties, and is comfortable to view. Further development of this method may result in a nonmydriatic and comfortable imaging method to quantify RPE atrophy extent and its expansion rate. PMID:26024124

  9. A straightforward graphical user interface for basic and advanced signal processing of thermographic infrared sequences

    Science.gov (United States)

    Klein, Matthieu T.; Ibarra-Castanedo, Clemente; Maldague, Xavier P.; Bendada, Abdelhakim

    2008-03-01

    IR-View, is a free and open source Matlab software that was released in 1998 at the Computer Vision and Systems Laboratory (CVSL) at Université Laval, Canada, as an answer to many common and recurrent needs in Infrared thermography. IR-View has proven to be a useful tool at CVSL for the past 10 years. The software by itself and/or its concept and functions may be of interest for other laboratories and companies working in research in the IR NDT field. This article describes the functions and processing techniques integrated to IR-View, freely downloadable under the GNU license at http://mivim.gel.ulaval.ca. Demonstration of IR-View functionalities will also be done during the DSS08 SPIE Defense and Security Symposium.

  10. Generation of broadly tunable picosecond mid-infrared laser and sensitive detection of a mid-infrared signal by parametric frequency up-conversion in MgO:LiNbO3 optical parametric amplifiers

    International Nuclear Information System (INIS)

    Zhang Qiu-Lin; Zhang Jing; Qiu Kang-Sheng; Zhang Dong-Xiang; Feng Bao-Hua; Zhang Jing-Yuan

    2012-01-01

    Picosecond optical parametric generation and amplification in the near-infrared region within 1.361–1.656 μm and the mid-infrared region within 2.976–4.875 μm is constructed on the basis of bulk MgO:LiNbO 3 crystals pumped at 1.064 μm. The maximum pulse energy reaches 1.3 mJ at 1.464 μm and 0.47 mJ at 3.894 μm, corresponding to a pump-to-idler photon conversion efficiency of 25%. By seeding the hard-to-measure mid-infrared radiation as the idler in the optical parametric amplification and measuring the amplified and frequency up-converted signal in the near-infrared or even visible region, one can measure very week mid-infrared radiation with ordinary detectors, which are insensitive to mid-infrared radiation, with a very high gain. A maximum gain factor of about 7 × 10 7 is achieved at the mid-infrared wavelength of 3.374 μm and the corresponding energy detection limit is as low as about 390 aJ per pulse. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  11. The use of net analyte signal (NAS) in near infrared spectroscopy pharmaceutical applications: interpretability and figures of merit.

    Science.gov (United States)

    Sarraguça, Mafalda Cruz; Lopes, João Almeida

    2009-05-29

    Near infrared spectroscopy (NIRS) has been extensively used as an analytical method for quality control of solid dosage forms for the pharmaceutical industry. Pharmaceutical formulations can be extremely complex, containing typically one or more active product ingredients (API) and various excipients, yielding very complex near infrared (NIR) spectra. The NIR spectra interpretability can be improved using the concept of net analyte signal (NAS). NAS is defined as the part of the spectrum unique to the analyte of interest. The objective of this work was to compare two different methods to estimate the API's NAS vector of different pharmaceutical formulations. The main difference between the methods is the knowledge of API free formulations NIR spectra. The comparison between the two methods was assessed in a qualitative and quantitative way. Results showed that both methods produced good results in terms of the similarity between the NAS vector and the pure API spectrum, as well as in the ability to predict the API concentration of unknown samples. Moreover, figures of merit such as sensitivity, selectivity, and limit of detection were estimated in a straightforward manner.

  12. Infrared thermography

    CERN Document Server

    Meola, Carosena

    2012-01-01

    This e-book conveys information about basic IRT theory, infrared detectors, signal digitalization and applications of infrared thermography in many fields such as medicine, foodstuff conservation, fluid-dynamics, architecture, anthropology, condition monitoring, non destructive testing and evaluation of materials and structures.

  13. Multi-Sensor Fusion of Infrared and Electro-Optic Signals for High Resolution Night Images

    Directory of Open Access Journals (Sweden)

    Victor Lawrence

    2012-07-01

    Full Text Available Electro-optic (EO image sensors exhibit the properties of high resolution and low noise level at daytime, but they do not work in dark environments. Infrared (IR image sensors exhibit poor resolution and cannot separate objects with similar temperature. Therefore, we propose a novel framework of IR image enhancement based on the information (e.g., edge from EO images, which improves the resolution of IR images and helps us distinguish objects at night. Our framework superimposing/blending the edges of the EO image onto the corresponding transformed IR image improves their resolution. In this framework, we adopt the theoretical point spread function (PSF proposed by Hardie et al. for the IR image, which has the modulation transfer function (MTF of a uniform detector array and the incoherent optical transfer function (OTF of diffraction-limited optics. In addition, we design an inverse filter for the proposed PSF and use it for the IR image transformation. The framework requires four main steps: (1 inverse filter-based IR image transformation; (2 EO image edge detection; (3 registration; and (4 blending/superimposing of the obtained image pair. Simulation results show both blended and superimposed IR images, and demonstrate that blended IR images have better quality over the superimposed images. Additionally, based on the same steps, simulation result shows a blended IR image of better quality when only the original IR image is available.

  14. Higgs and supersymmetric particle signals at the infrared fixed point of the top quark mass

    International Nuclear Information System (INIS)

    Carena, M.; Wagner, C.E.M.

    1995-01-01

    We study the properties of the Higgs and supersymmetric particle spectrum, associated with the infrared fixed point solution of the top quark mass in the Minimal Supersymmetric Standard Model. We concentrate on the possible detection of these particles, analysing the deviations from the Standard Model predictions for the leptonic and hadronic variables measured at LEP and for the b→sγ decay rate. We consider the low and moderate tan β regime, imposing the constraints derived from a proper radiative SU(2) L xU(1) Y symmetry breaking, and we study both the cases of universal and non-universal soft supersymmetry-breaking parameters at high energies. In the first case, for any given value of the top quark mass, the Higgs and supersymmetric particle spectrum is completely determined as a function of only two soft supersymmetry-breaking parameters, implying very definite experimental signatures. In the case of non-universal mass parameters at M GUT , instead, the strong correlations between the sparticle masses are relaxed, allowing a richer structure for the precision data variables. As a general feature, whenever a significant deviation from the Standard Model value of the precision data parameters is predicted, a light sparticle, which should be visible at LEP2, appears in the model. (orig.)

  15. On the shape of continuous wave infrared stimulated luminescence signals from feldspars: A case study

    DEFF Research Database (Denmark)

    Pagonis, V.; Jain, Mayank; Thomsen, Kristina Jørkov

    2014-01-01

    The continuous-wave IRSL (CW-IRSL) signals from feldspars are known to decay in a non-exponential manner, and their exact mathematical description is of great importance in dosimetric and dating studies. This paper investigates the possibility of fitting experimental CW-IRSL curves from a variety...... to guide future modeling work on luminescence processes in feldspars. Small statistical differences were found between K-rich and Na-rich fractions of the same sample. However, the experimental data shows that the parameters depend on the irradiation dose, but do not depend on the time elapsed after...

  16. Prey capture by harbour porpoises

    DEFF Research Database (Denmark)

    Verfuss, Ursula; Miller, Lee; Pilz, Peter

    their ultrasonic clicks as biosonar for orientation and detection of prey (mostly smaller pelagic and bottom dwelling fish), and for communication.  For studying wild animals, hydrophone arrays [Villadsgaard et al. J.Exp.Biol. 210 (2007)] and acoustic (time/depth) tags [Akamatsu et al. Deep Sea Research II 54...... (2007)] have been used.  For studying captive animals, arrays and video techniques [Verfuß et al. J.Exp.Biol. 208 (2005)] as well as miniature acoustic-behavioral tags [Deruiter et al. JASA 123 (2008)] have been used.  While searching for prey, harbor porpoises use clicks at long intervals (>50 ms......) that progressively decrease when closing on a landmark.  The source levels of captive animals reduce by about half for each halving of the distance to the target.  After detecting the prey, the click interval first stabilizes at about 50 ms and then becomes progressively shorter while approaching the prey...

  17. Monitoring Local Regional Hemodynamic Signal Changes during Motor Execution and Motor Imagery Using Near-Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    Naoki eIso

    2016-01-01

    Full Text Available The aim of this study was to clarify the topographical localization of motor-related regional hemodynamic signal changes during motor execution (ME and motor imagery (MI by using near-infrared spectroscopy (NIRS, as this technique is more clinically expedient than established methods (e.g. fMRI. Twenty right-handed healthy subjects participated in this study. The experimental protocol was a blocked design consisting of 3 cycles of 20 s of task performance and 30 s of rest. The tapping sequence task was performed with their fingers under 4 conditions: ME and MI with the right or left hand. Hemodynamic brain activity was measured with NIRS to monitor changes in oxygenated hemoglobin (oxy-Hb concentration. Oxy-Hb in the somatosensory motor cortex (SMC increased significantly only during contralateral ME and showed a significant interaction between task and hand. There was a main effect of hand in the left SMC. Although there were no significant main effects or interactions in the supplemental motor area (SMA and premotor area (PMA, oxy-Hb increased substantially under all conditions. These results clarified the topographical localization by motor-related regional hemodynamic signal changes during ME and MI by using NIRS.

  18. Dynamics analysis of a predator-prey system with harvesting prey and disease in prey species.

    Science.gov (United States)

    Meng, Xin-You; Qin, Ni-Ni; Huo, Hai-Feng

    2018-12-01

    In this paper, a predator-prey system with harvesting prey and disease in prey species is given. In the absence of time delay, the existence and stability of all equilibria are investigated. In the presence of time delay, some sufficient conditions of the local stability of the positive equilibrium and the existence of Hopf bifurcation are obtained by analysing the corresponding characteristic equation, and the properties of Hopf bifurcation are given by using the normal form theory and centre manifold theorem. Furthermore, an optimal harvesting policy is investigated by applying the Pontryagin's Maximum Principle. Numerical simulations are performed to support our analytic results.

  19. Dominant Glint Based Prey Localization in Horseshoe Bats: A Possible Strategy for Noise Rejection

    OpenAIRE

    Vanderelst, Dieter; Reijniers, Jonas; Firzlaff, Uwe; Peremans, Herbert

    2011-01-01

    Rhinolophidae or Horseshoe bats emit long and narrowband calls. Fluttering insect prey generates echoes in which amplitude and frequency shifts are present, i.e. glints. These glints are reliable cues about the presence of prey and also encode certain properties of the prey. In this paper, we propose that these glints, i.e. the dominant glints, are also reliable signals upon which to base prey localization. In contrast to the spectral cues used by many other bats, the localization cues in Rhi...

  20. Process-based models of feeding and prey selection in larval fish

    DEFF Research Database (Denmark)

    Fiksen, O.; MacKenzie, Brian

    2002-01-01

    believed to be important to prey selectivity and environmental regulation of feeding in fish. We include the sensitivity of prey to the hydrodynamic signal generated by approaching larval fish and a simple model of the potential loss of prey due to turbulence whereby prey is lost if it leaves...... jig dry wt l(-1). The spatio-temporal fluctuation of turbulence (tidal cycle) and light (sun height) over the bank generates complex structure in the patterns of food intake of larval fish, with different patterns emerging for small and large larvae....

  1. Perceiving the algae: How feeding-current feeding copepods detect their nonmotile prey

    DEFF Research Database (Denmark)

    Goncalves, Rodrigo J.; Kiørboe, Thomas

    2015-01-01

    demonstrate that (1) long-range chemical detection is incompatible with known algal leakage rates and reasonable assumptions of sensitivity, (2) that near-field chemical detection is constrained by diffusion across the boundary layer of the sensor and takes longer than observed near-contact times, and (3......Feeding-current feeding copepods detect and capture prey individually, but the mechanism by which nonmotile prey is detected has been unclear. Early reports that copepods detect phytoplankton prey at distances of one body length or more led to the hypothesis that solutes leaking from the prey would......) that most reported detection distances are well predicted by models of fluid mechanical signal generation and detection. We conclude that near-field mechanoreception is the common prey detection mode in pelagic copepods. Prey detection distances are thus governed mainly by the reach of the feeding...

  2. Near-infrared spectra of Penicillium camemberti strains separated by extended multiplicative signal correction improved prediction of physical and chemical variations

    DEFF Research Database (Denmark)

    Decker, Marianne; Nielsen, Per Væggemose; Martens, Harald

    2005-01-01

    signal correction (TWEMSC) preprocessing, whereby three patterns of variation in near-infrared (NIR) log(1/R) spectra of fungal colonies could be separated mathematically: (1) physical light scattering and its wavelength dependency, (2) differences in light absorption of water due to varying sample...

  3. Determination of the wavelength dependence of the differential pathlength factor from near-infrared pulse signals

    Science.gov (United States)

    Kohl, Matthias; Nolte, Christian; Heekeren, Hauke R.; Horst, Susanne; Scholz, Udo; Obrig, Hellmuth; Villringer, Arno

    1998-06-01

    For the calculation of changes in oxyhaemoglobin, deoxyhaemoglobin and the redox state of cytochrome-c-oxidase from attenuation data via a modified Beer-Lambert equation the wavelength dependence of the differential pathlength factor (DPF) has to be taken into account. The DPF, i.e. the ratio of the mean optical pathlength and the physical light source-detector separation at each wavelength, determines the crosstalk between the different concentrations and is therefore essential for a sensitive detection of chromophore changes. Here a simple method is suggested to estimate the wavelength dependence of the DPF from pulse-induced attenuation changes measured on the head of adult humans. The essence is that the DPF is the ratio of the attenuation changes over absorption coefficient changes, and that the spectral form of the pulse correlated absorption coefficient change can be assumed to be proportional to the extinction coefficient of blood. Indicators for the validity of the DPF derived for wavelengths between 700 and 970 nm are the stability of the calculated haemoglobin and cytochrome signals with variations of the wavelength range included for their calculation and its overall agreement with the data available from the literature.

  4. A HWIL test facility of infrared imaging laser radar using direct signal injection

    Science.gov (United States)

    Wang, Qian; Lu, Wei; Wang, Chunhui; Wang, Qi

    2005-01-01

    Laser radar has been widely used these years and the hardware-in-the-loop (HWIL) testing of laser radar become important because of its low cost and high fidelity compare with On-the-Fly testing and whole digital simulation separately. Scene generation and projection two key technologies of hardware-in-the-loop testing of laser radar and is a complicated problem because the 3D images result from time delay. The scene generation process begins with the definition of the target geometry and reflectivity and range. The real-time 3D scene generation computer is a PC based hardware and the 3D target models were modeled using 3dsMAX. The scene generation software was written in C and OpenGL and is executed to extract the Z-buffer from the bit planes to main memory as range image. These pixels contain each target position x, y, z and its respective intensity and range value. Expensive optical injection technologies of scene projection such as LDP array, VCSEL array, DMD and associated scene generation is ongoing. But the optical scene projection is complicated and always unaffordable. In this paper a cheaper test facility was described that uses direct electronic injection to provide rang images for laser radar testing. The electronic delay and pulse shaping circuits inject the scenes directly into the seeker's signal processing unit.

  5. Signal-to-noise contribution of principal component loads in reconstructed near-infrared Raman tissue spectra.

    Science.gov (United States)

    Grimbergen, M C M; van Swol, C F P; Kendall, C; Verdaasdonk, R M; Stone, N; Bosch, J L H R

    2010-01-01

    The overall quality of Raman spectra in the near-infrared region, where biological samples are often studied, has benefited from various improvements to optical instrumentation over the past decade. However, obtaining ample spectral quality for analysis is still challenging due to device requirements and short integration times required for (in vivo) clinical applications of Raman spectroscopy. Multivariate analytical methods, such as principal component analysis (PCA) and linear discriminant analysis (LDA), are routinely applied to Raman spectral datasets to develop classification models. Data compression is necessary prior to discriminant analysis to prevent or decrease the degree of over-fitting. The logical threshold for the selection of principal components (PCs) to be used in discriminant analysis is likely to be at a point before the PCs begin to introduce equivalent signal and noise and, hence, include no additional value. Assessment of the signal-to-noise ratio (SNR) at a certain peak or over a specific spectral region will depend on the sample measured. Therefore, the mean SNR over the whole spectral region (SNR(msr)) is determined in the original spectrum as well as for spectra reconstructed from an increasing number of principal components. This paper introduces a method of assessing the influence of signal and noise from individual PC loads and indicates a method of selection of PCs for LDA. To evaluate this method, two data sets with different SNRs were used. The sets were obtained with the same Raman system and the same measurement parameters on bladder tissue collected during white light cystoscopy (set A) and fluorescence-guided cystoscopy (set B). This method shows that the mean SNR over the spectral range in the original Raman spectra of these two data sets is related to the signal and noise contribution of principal component loads. The difference in mean SNR over the spectral range can also be appreciated since fewer principal components can

  6. Post-attack aposematic display in prey facilitates predator avoidance learning

    Directory of Open Access Journals (Sweden)

    Changku eKang

    2016-04-01

    Full Text Available Warning signals protect unpalatable prey from predation because predators who learn the association between the warning signal and prey unprofitability decrease attacks on the prey. Most of the research have focused on visual aposematic signals that are constantly presented and visible to the predators. But a variety of chemically defended insects are rather cryptic when resting, and only in response to predator attacks (post-attack they perform displays of conspicuous abdomens or hindwings normally hidden under forewings. The function of those displays in unpalatable insects is not well understood. We examined two adaptive hypotheses on this facultative aposematic display using wild-caught oriental tits (Parus minor as predators. First, we tested whether the display increases the rejection of the prey by predators upon seeing the display (i.e. at the moment of attack through learning trials (aposematic signaling hypothesis. Second, we tested whether the display facilitates the memory formation between cryptic visible form of the prey and prey defense so that it prevents the predators initiate an attack upon seeing the cryptic form (facilitation hypothesis. We found that predators learned to avoid attacking the prey which supports the facilitation hypothesis. However, the support for the aposematic signaling hypothesis was equivocal. Our results open new directions of research by highlighting the possibility that similar facilitation effects may contribute to the evolution of various forms of post-attack visual displays in chemically, or otherwise, defended animals.

  7. Sub-indicator: Prey fish

    Science.gov (United States)

    Weidel, Brian C.; Dunlop, Erin

    2017-01-01

    Prey fish communities across the Great Lakes continue to change, although the direction and magnitude of those changes are not consistent across the lakes. The metrics used to categorize prey fish status in this and previous periods are based on elements that are common among each of the lake’s Fish Community Objectives and include diversity and the relative role of native species in the prey fish communities. The diversity index categorized three of lakes as ‘fair’, while Superior and Erie were ‘good’ (Table 1). The short term trend, from the previous period (2008-2010) to the current period (2011-2014) found diversity in Erie and Superior to be unchanging, but the other three lakes to be ‘deteriorating’, resulting in an overall trend categorization of ‘undetermined’ (Table 1). The long term diversity trend suggested Lakes Superior and Erie have the most diverse prey communities although the index for those prey fish have been quite variable over time (Figure 1). In Lake Huron, where non-native alewife have substantially declined, the diversity index has also declined. The continued dominance of alewife in Lake Ontario (96% of the prey fish biomass) resulted in the lowest diversity index value (Figure 1). The proportion of native species within the community was judged as ‘good’ in Lakes Superior and Huron, ‘fair’ in Michigan and Erie and ‘poor’ in Ontario (Table 2). The short term trend was improving in in all lakes except Michigan (‘deteriorating’) and Ontario (‘unchanging’), resulting in an overall short term trend of ‘undetermined’ (Table 2). Over the current period, Lake Superior consistently had the highest proportion native prey fish (87%) while Lake Ontario had the lowest (1%) (Figure 2). Lake Michigan’s percent native has declined as round goby increase and comprises a greater proportion of the community. Native prey fish make up 51% of Lake Erie, although basin-specific values differed (Figure 2). Most notably

  8. Jewelled spiders manipulate colour-lure geometry to deceive prey.

    Science.gov (United States)

    White, Thomas E

    2017-03-01

    Selection is expected to favour the evolution of efficacy in visual communication. This extends to deceptive systems, and predicts functional links between the structure of visual signals and their behavioural presentation. Work to date has primarily focused on colour, however, thereby understating the multicomponent nature of visual signals. Here I examined the relationship between signal structure, presentation behaviour, and efficacy in the context of colour-based prey luring. I used the polymorphic orb-web spider Gasteracantha fornicata , whose yellow- or white-and-black striped dorsal colours have been broadly implicated in prey attraction. In a manipulative assay, I found that spiders actively control the orientation of their conspicuous banded signals in the web, with a distinct preference for near-diagonal bearings. Further field-based study identified a predictive relationship between pattern orientation and prey interception rates, with a local maximum at the spiders' preferred orientation. There were no morph-specific effects on capture success, either singularly or via an interaction with pattern orientation. These results reveal a dynamic element in a traditionally 'static' signalling context, and imply differential functions for chromatic and geometric signal components across visual contexts. More broadly, they underscore how multicomponent signal designs and display behaviours may coevolve to enhance efficacy in visual deception. © 2017 The Author(s).

  9. Prey capture by harbor porpoises

    DEFF Research Database (Denmark)

    Miller, Lee; Verfuss, Ursula

    2009-01-01

    their ultrasonic clicks as biosonar for orientation and detection of prey (mostly smaller pelagic and bottom dwelling fish), and for communication. For studying wild animals, hydrophone arrays and acoustic (time/depth) tags have been used. For studying captive animals, arrays and video techniques as well...

  10. Two-prey one-predator model

    International Nuclear Information System (INIS)

    Elettreby, M.F.

    2009-01-01

    In this paper we propose a new multi-team prey-predator model, in which the prey teams help each other. We study its local stability. In the absence of predator, there is no help between the prey teams. So, we study the global stability and persistence of the model without help.

  11. Prey detection in a cruising copepod

    DEFF Research Database (Denmark)

    Kjellerup, Sanne; Kiørboe, Thomas

    2012-01-01

    . Yet, direct interception has been proposed to explain how rapidly cruising, blind copepods feed on non-motile phytoplankton prey. Here, we demonstrate a novel mechanism for prey detection in a cruising copepod, and describe how motile and non-motile prey are discovered by hydromechanical and tactile...

  12. When attempts at robbing prey turn fatal

    Science.gov (United States)

    Dejean, Alain; Corbara, Bruno; Azémar, Frédéric; Carpenter, James M.

    2012-07-01

    Because group-hunting arboreal ants spread-eagle insect prey for a long time before retrieving them, these prey can be coveted by predatory flying insects. Yet, attempting to rob these prey is risky if the ant species is also an effective predator. Here, we show that trying to rob prey from Azteca andreae workers is a fatal error as 268 out of 276 potential cleptobionts (97.1 %) were captured in turn. The ant workers hunt in a group and use the "Velcro®" principle to cling firmly to the leaves of their host tree, permitting them to capture very large prey. Exceptions were one social wasp, plus some Trigona spp. workers and flies that landed directly on the prey and were able to take off immediately when attacked. We conclude that in this situation, previously captured prey attract potential cleptobionts that are captured in turn in most of the cases.

  13. Penguin head movement detected using small accelerometers: a proxy of prey encounter rate.

    Science.gov (United States)

    Kokubun, Nobuo; Kim, Jeong-Hoon; Shin, Hyoung-Chul; Naito, Yasuhiko; Takahashi, Akinori

    2011-11-15

    Determining temporal and spatial variation in feeding rates is essential for understanding the relationship between habitat features and the foraging behavior of top predators. In this study we examined the utility of head movement as a proxy of prey encounter rates in medium-sized Antarctic penguins, under the presumption that the birds should move their heads actively when they encounter and peck prey. A field study of free-ranging chinstrap and gentoo penguins was conducted at King George Island, Antarctica. Head movement was recorded using small accelerometers attached to the head, with simultaneous monitoring for prey encounter or body angle. The main prey was Antarctic krill (>99% in wet mass) for both species. Penguin head movement coincided with a slow change in body angle during dives. Active head movements were extracted using a high-pass filter (5 Hz acceleration signals) and the remaining acceleration peaks (higher than a threshold acceleration of 1.0 g) were counted. The timing of head movements coincided well with images of prey taken from the back-mounted cameras: head movement was recorded within ±2.5 s of a prey image on 89.1±16.1% (N=7 trips) of images. The number of head movements varied largely among dive bouts, suggesting large temporal variations in prey encounter rates. Our results show that head movement is an effective proxy of prey encounter, and we suggest that the method will be widely applicable for a variety of predators.

  14. Hemodynamic and electrophysiological signals of conflict processing in the Chinese-character Stroop task: a simultaneous near-infrared spectroscopy and event-related potential study.

    Science.gov (United States)

    Zhai, Jiahuan; Li, Ting; Zhang, Zhongxing; Gong, Hui

    2009-01-01

    A dual-modality method combining continuous-wave near-infrared spectroscopy (NIRS) and event-related potentials (ERPs) was developed for the Chinese-character color-word Stroop task, which included congruent, incongruent, and neutral stimuli. Sixteen native Chinese speakers participated in this study. Hemodynamic and electrophysiological signals in the prefrontal cortex (PFC) were monitored simultaneously by NIRS and ERP. The hemodynamic signals were represented by relative changes in oxy-, deoxy-, and total hemoglobin concentration, whereas the electrophysiological signals were characterized by the parameters P450, N500, and P600. Both types of signals measured at four regions of the PFC were analyzed and compared spatially and temporally among the three different stimuli. We found that P600 signals correlated significantly with the hemodynamic parameters, suggesting that the PFC executes conflict-solving function. Additionally, we observed that the change in deoxy-Hb concentration showed higher sensitivity in response to the Stroop task than other hemodynamic signals. Correlation between NIRS and ERP signals revealed that the vascular response reflects the cumulative effect of neural activities. Taken together, our findings demonstrate that this new dual-modality method is a useful approach to obtaining more information during cognitive and physiological studies.

  15. Interspecific variation in prey capture behavior by co-occurring Nepenthes pitcher plants

    Science.gov (United States)

    Chin, Lijin; Chung, Arthur YC; Clarke, Charles

    2014-01-01

    Pitcher plants of the genus Nepenthes capture a wide range of arthropod prey for nutritional benefit, using complex combinations of visual and olfactory signals and gravity-driven pitfall trapping mechanisms. In many localities throughout Southeast Asia, several Nepenthes different species occur in mixed populations. Often, the species present at any given location have strongly divergent trap structures and preliminary surveys indicate that different species trap different combinations of arthropod prey, even when growing at the same locality. On this basis, it has been proposed that co-existing Nepenthes species may be engaged in niche segregation with regards to arthropod prey, avoiding direct competition with congeners by deploying traps that have modifications that enable them to target specific prey types. We examined prey capture among 3 multi-species Nepenthes populations in Borneo, finding that co-existing Nepenthes species do capture different combinations of prey, but that significant interspecific variations in arthropod prey combinations can often be detected only at sub-ordinal taxonomic ranks. In all lowland Nepenthes species examined, the dominant prey taxon is Formicidae, but montane Nepenthes trap few (or no) ants and 2 of the 3 species studied have evolved to target alternative sources of nutrition, such as tree shrew feces. Using similarity and null model analyses, we detected evidence for niche segregation with regards to formicid prey among 5 lowland, sympatric Nepenthes species in Sarawak. However, we were unable to determine whether these results provide support for the niche segregation hypothesis, or whether they simply reflect unquantified variation in heterogeneous habitats and/or ant communities in the study sites. These findings are used to propose improvements to the design of field experiments that seek to test hypotheses about targeted prey capture patterns in Nepenthes. PMID:24481246

  16. Signal-to-Noise Contribution of Principal Component Loads in Reconstructed Near-Infrared Raman Tissue Spectra

    NARCIS (Netherlands)

    Grimbergen, M. C. M.; van Swol, C. F. P.; Kendall, C.; Verdaasdonk, R. M.; Stone, N.; Bosch, J. L. H. R.

    The overall quality of Raman spectra in the near-infrared region, where biological samples are often studied, has benefited from various improvements to optical instrumentation over the past decade. However, obtaining ample spectral quality for analysis is still challenging due to device

  17. The modeling of predator-prey interactions

    OpenAIRE

    Muhammad Shakil; H. A. Wahab; Muhammad Naeem, et al.

    2015-01-01

    In this paper, we aim to study the interactions between the territorial animals like foxes and the rabbits. The territories for the foxes are considered to be the simple cells. The interactions between predator and its prey are represented by the chemical reactions which obey the mass action law. In this sense, we apply the mass action law for predator prey models and the quasi chemical approach is applied for the interactions between the predator and its prey to develop the modeled equations...

  18. Simple locking of infrared and ultraviolet diode lasers to a visible laser using a LabVIEW proportional-integral-derivative controller on a Fabry-Perot signal.

    Science.gov (United States)

    Kwolek, J M; Wells, J E; Goodman, D S; Smith, W W

    2016-05-01

    Simultaneous laser locking of infrared (IR) and ultraviolet lasers to a visible stabilized reference laser is demonstrated via a Fabry-Perot (FP) cavity. LabVIEW is used to analyze the input, and an internal proportional-integral-derivative algorithm converts the FP signal to an analog locking feedback signal. The locking program stabilized both lasers to a long term stability of better than 9 MHz, with a custom-built IR laser undergoing significant improvement in frequency stabilization. The results of this study demonstrate the viability of a simple, computer-controlled, non-temperature-stabilized FP locking scheme for our applications, laser cooling of Ca(+) ions, and its use in other applications with similar modest frequency stabilization requirements.

  19. "Prey Play": Learning about Predators and Prey through an Interactive, Role-Play Game

    Science.gov (United States)

    Deaton, Cynthia C. M.; Dodd, Kristen; Drennon, Katherine; Nagle, Jack

    2012-01-01

    "Prey Play" is an interactive role-play activity that provides fifth-grade students with opportunities to examine predator-prey interactions. This four-part, role-play activity allows students to take on the role of a predator and prey as they reflect on the behaviors animals exhibit as they collect food and interact with one another, as well as…

  20. Prey size spectra and prey availability of larval and small juvenile cod

    DEFF Research Database (Denmark)

    Munk, Peter

    1997-01-01

    The aim of the present study is to describe the prey preference characteristics of cod larvae and assess preference variability in relation to species and size composition of copepod prey. A further aim is to examine the hypothesis that dietary prey size spectra remain the same during the larval ...... were indicated, dependent on location. The findings illustrate the usefulness of coupling dietary prey size spectra and biomass spectra of available prey sizes during studies of ichthyoplankton feeding ecology. (C) 1997 The Fisheries Society of the British Isles....

  1. Relating marten scat contents to prey consumed

    Science.gov (United States)

    William J. Zielinski

    1986-01-01

    A European ferret, Mustela putorius furo, was fed typical marten food items to discover the relationship between prey weight and number of scats produced per unit weight of prey. A correction factor was derived that was used in the analysis of pine marten, Martes americana, scats to produce a method capable of comparing foods on a...

  2. Greater contribution of cerebral than extracerebral hemodynamics to near-infrared spectroscopy signals for functional activation and resting-state connectivity in infants.

    Science.gov (United States)

    Funane, Tsukasa; Homae, Fumitaka; Watanabe, Hama; Kiguchi, Masashi; Taga, Gentaro

    2014-10-01

    While near-infrared spectroscopy (NIRS) has been increasingly applied to neuroimaging and functional connectivity studies in infants, it has not been quantitatively examined as to what extent the deep tissue (such as cerebral tissue) as opposed to shallow tissue (such as scalp), contributes to NIRS signals measured in infants. A method for separating the effects of deep- and shallow-tissue layers was applied to data of nine sleeping three-month-old infants who had been exposed to 3-s speech sounds or silence (i.e., resting state) and whose hemodynamic changes over their bilateral temporal cortices had been measured by using an NIRS system with multiple source-detector (S-D) distances. The deep-layer contribution was found to be large during resting [67% at S-D 20 mm, 78% at S-D 30 mm for oxygenated hemoglobin (oxy-Hb)] as well as during the speech condition (72% at S-D 20 mm, 82% at S-D 30 mm for oxy-Hb). A left-right connectivity analysis showed that correlation coefficients between left and right channels did not differ between original- and deep-layer signals under no-stimulus conditions and that of original- and deep-layer signals were larger than those of the shallow layer. These results suggest that NIRS signals obtained in infants with appropriate S-D distances largely reflected cerebral hemodynamic changes.

  3. Optimal intermittent search strategies: smelling the prey

    International Nuclear Information System (INIS)

    Revelli, J A; Wio, H S; Rojo, F; Budde, C E

    2010-01-01

    We study the kinetics of the search of a single fixed target by a searcher/walker that performs an intermittent random walk, characterized by different states of motion. In addition, we assume that the walker has the ability to detect the scent left by the prey/target in its surroundings. Our results, in agreement with intuition, indicate that the prey's survival probability could be strongly reduced (increased) if the predator is attracted (or repelled) by the trace left by the prey. We have also found that, for a positive trace (the predator is guided towards the prey), increasing the inhomogeneity's size reduces the prey's survival probability, while the optimal value of α (the parameter that regulates intermittency) ceases to exist. The agreement between theory and numerical simulations is excellent.

  4. Optimal intermittent search strategies: smelling the prey

    Energy Technology Data Exchange (ETDEWEB)

    Revelli, J A; Wio, H S [Instituto de Fisica de Cantabria, Universidad de Cantabria and CSIC, E-39005 Santander (Spain); Rojo, F; Budde, C E [Fa.M.A.F., Universidad Nacional de Cordoba, Ciudad Universitaria, X5000HUA Cordoba (Argentina)

    2010-05-14

    We study the kinetics of the search of a single fixed target by a searcher/walker that performs an intermittent random walk, characterized by different states of motion. In addition, we assume that the walker has the ability to detect the scent left by the prey/target in its surroundings. Our results, in agreement with intuition, indicate that the prey's survival probability could be strongly reduced (increased) if the predator is attracted (or repelled) by the trace left by the prey. We have also found that, for a positive trace (the predator is guided towards the prey), increasing the inhomogeneity's size reduces the prey's survival probability, while the optimal value of {alpha} (the parameter that regulates intermittency) ceases to exist. The agreement between theory and numerical simulations is excellent.

  5. Construction of a Near-Infrared-Activatable Enzyme Platform To Remotely Trigger Intracellular Signal Transduction Using an Upconversion Nanoparticle.

    Science.gov (United States)

    Gao, Hua-De; Thanasekaran, Pounraj; Chiang, Chao-Wei; Hong, Jia-Lin; Liu, Yen-Chun; Chang, Yu-Hsu; Lee, Hsien-Ming

    2015-07-28

    Photoactivatable (caged) bioeffectors provide a way to remotely trigger or disable biochemical pathways in living organisms at a desired time and location with a pulse of light (uncaging), but the phototoxicity of ultraviolet (UV) often limits its application. In this study, we have demonstrated the near-infrared (NIR) photoactivatable enzyme platform using protein kinase A (PKA), an important enzyme in cell biology. We successfully photoactivated PKA using NIR to phosphorylate its substrate, and this induced a downstream cellular response in living cells with high spatiotemporal resolution. In addition, this system allows NIR to selectively activate the caged enzyme immobilized on the nanoparticle surface without activating other caged proteins in the cytosol. This NIR-responsive enzyme-nanoparticle system provides an innovative approach to remote-control proteins and enzymes, which can be used by researchers who need to avoid direct UV irradiation or use UV as a secondary channel to turn on a bioeffector.

  6. Prey preferences of the jaguar Panthera onca reflect the post-Pleistocene demise of large prey.

    Directory of Open Access Journals (Sweden)

    Matt W Hayward

    2016-01-01

    Full Text Available Documenting the impacts of the Pleistocene megafaunal extinctions on predator-prey interactions is a challenge because of the incomplete fossil record and depauperate extant community structure. We used a comparative ecological approach to investigate whether the existing prey preference patterns of jaguars Panthera onca were potentially affected by the Pleistocene extinctions in the Americas compared with large felids in Africa and Asia. We reviewed the literature and found 25 studies reporting 3214 jaguar kills recorded throughout the species’ distribution. We found that jaguars significantly preferred capybara Hydrochaeris hydrochaeris and giant anteater Myrmecophaga tridactyla, and avoided agoutis, carnivorans, primates, black-eared opossum Didelphis marsupialis and tapirs. Generalised linear models showed that jaguars select prey primarily based on socio-ecological and behavioural traits (abundance and herd size, rather than morphological characteristics (body size. Nonetheless, their accessible prey weight range was 6-60 kg, preferred prey weight range was 45-85 kg, and mean mass of significantly preferred prey was 32 ± 13 kg leading to a predator to prey body mass ratio of 1:0.53, which is much less than that of other solitary felids. Compared with other large, solitary felids, jaguars have an unusual predator to prey body mass ratio, show limited effect of prey morphology as a driver of prey selection, lack evidence of optimal foraging beyond their preferred prey, and an absence of preferentially hunting on Cetartiodactyla herbivores. These features, coupled with the reduction in jaguar body mass since the Pleistocene, suggest that the loss of larger potential prey items within the preferred and accessible weight ranges at the end-Pleistocene still affects jaguar predatory behaviour. It may be that jaguars survived this mass extinction event by preferentially preying on relatively small species.

  7. Influence of spectral resolution, spectral range and signal-to-noise ratio of Fourier transform infra-red spectra on identification of high explosive substances

    Science.gov (United States)

    Banas, Krzysztof; Banas, Agnieszka M.; Heussler, Sascha P.; Breese, Mark B. H.

    2018-01-01

    In the contemporary spectroscopy there is a trend to record spectra with the highest possible spectral resolution. This is clearly justified if the spectral features in the spectrum are very narrow (for example infra-red spectra of gas samples). However there is a plethora of samples (in the liquid and especially in the solid form) where there is a natural spectral peak broadening due to collisions and proximity predominately. Additionally there is a number of portable devices (spectrometers) with inherently restricted spectral resolution, spectral range or both, which are extremely useful in some field applications (archaeology, agriculture, food industry, cultural heritage, forensic science). In this paper the investigation of the influence of spectral resolution, spectral range and signal-to-noise ratio on the identification of high explosive substances by applying multivariate statistical methods on the Fourier transform infra-red spectral data sets is studied. All mathematical procedures on spectral data for dimension reduction, clustering and validation were implemented within R open source environment.

  8. Echolocating bats cry out loud to detect their prey.

    Directory of Open Access Journals (Sweden)

    Annemarie Surlykke

    Full Text Available Echolocating bats have successfully exploited a broad range of habitats and prey. Much research has demonstrated how time-frequency structure of echolocation calls of different species is adapted to acoustic constraints of habitats and foraging behaviors. However, the intensity of bat calls has been largely neglected although intensity is a key factor determining echolocation range and interactions with other bats and prey. Differences in detection range, in turn, are thought to constitute a mechanism promoting resource partitioning among bats, which might be particularly important for the species-rich bat assemblages in the tropics. Here we present data on emitted intensities for 11 species from 5 families of insectivorous bats from Panamá hunting in open or background cluttered space or over water. We recorded all bats in their natural habitat in the field using a multi-microphone array coupled with photographic methods to assess the bats' position in space to estimate emitted call intensities. All species emitted intense search signals. Output intensity was reduced when closing in on background by 4-7 dB per halving of distance. Source levels of open space and edge space foragers (Emballonuridae, Mormoopidae, Molossidae, and Vespertilionidae ranged between 122-134 dB SPL. The two Noctilionidae species hunting over water emitted the loudest signals recorded so far for any bat with average source levels of ca. 137 dB SPL and maximum levels above 140 dB SPL. In spite of this ten-fold variation in emitted intensity, estimates indicated, surprisingly, that detection distances for prey varied far less; bats emitting the highest intensities also emitted the highest frequencies, which are severely attenuated in air. Thus, our results suggest that bats within a local assemblage compensate for frequency dependent attenuation by adjusting the emitted intensity to achieve comparable detection distances for prey across species. We conclude that for bats

  9. The Dynamics of a Nonautonomous Predator-Prey Model with Infertility Control in the Prey

    Directory of Open Access Journals (Sweden)

    Xiaomei Feng

    2014-01-01

    Full Text Available A nonautonomous predator-prey model with infertility control in the prey is formulated and investigated. Threshold conditions for the permanence and extinction of fertility prey and infertility prey are established. Some new threshold values of integral form are obtained. For the periodic cases, these threshold conditions act as sharp threshold values for the permanence and extinction of fertility prey and infertility prey. There are also mounting concerns that the quantity of biological sterile drug is obtained in the process of the prevention and control of pest in the grasslands and farmland. Finally, two examples are given to illustrate the main results of this paper. The numerical simulations shown that, when the pest population is permanet, different dynamic behaviors may be found in this model, such as the global attractivity and the chaotic attractor.

  10. Gluttonous predators: how to estimate prey size when there are too many prey

    Directory of Open Access Journals (Sweden)

    MS. Araújo

    Full Text Available Prey size is an important factor in food consumption. In studies of feeding ecology, prey items are usually measured individually using calipers or ocular micrometers. Among amphibians and reptiles, there are species that feed on large numbers of small prey items (e.g. ants, termites. This high intake makes it difficult to estimate prey size consumed by these animals. We addressed this problem by developing and evaluating a procedure for subsampling the stomach contents of such predators in order to estimate prey size. Specifically, we developed a protocol based on a bootstrap procedure to obtain a subsample with a precision error of at the most 5%, with a confidence level of at least 95%. This guideline should reduce the sampling effort and facilitate future studies on the feeding habits of amphibians and reptiles, and also provide a means of obtaining precise estimates of prey size.

  11. Chemical basis of prey recognition in thamnophiine snakes: the unexpected new roles of parvalbumins.

    Directory of Open Access Journals (Sweden)

    Maïté Smargiassi

    Full Text Available Detecting and locating prey are key to predatory success within trophic chains. Predators use various signals through specialized visual, olfactory, auditory or tactile sensory systems to pinpoint their prey. Snakes chemically sense their prey through a highly developed auxiliary olfactory sense organ, the vomeronasal organ (VNO. In natricine snakes that are able to feed on land and water, the VNO plays a critical role in predatory behavior by detecting cues, known as vomodors, which are produced by their potential prey. However, the chemical nature of these cues remains unclear. Recently, we demonstrated that specific proteins-parvalbumins-present in the cutaneous mucus of the common frog (Rana temporaria may be natural chemoattractive proteins for these snakes. Here, we show that parvalbumins and parvalbumin-like proteins, which are mainly intracellular, are physiologically present in the epidermal mucous cells and mucus of several frog and fish genera from both fresh and salt water. These proteins are located in many tissues and function as Ca(2+ buffers. In addition, we clarified the intrinsic role of parvalbumins present in the cutaneous mucus of amphibians and fishes. We demonstrate that these Ca(2+-binding proteins participate in innate bacterial defense mechanisms by means of calcium chelation. We show that these parvalbumins are chemoattractive for three different thamnophiine snakes, suggesting that these chemicals play a key role in their prey-recognition mechanism. Therefore, we suggest that recognition of parvalbumin-like proteins or other calcium-binding proteins by the VNO could be a generalized prey-recognition process in snakes. Detecting innate prey defense mechanism compounds may have driven the evolution of this predator-prey interaction.

  12. Prey-mediated avoidance of an intraguild predator by its intraguild prey

    Science.gov (United States)

    Wilson, R.R.; Blankenship, T.L.; Hooten, M.B.; Shivik, J.A.

    2010-01-01

    Intraguild (IG) predation is an important factor influencing community structure, yet factors allowing coexistence of IG predator and IG prey are not well understood. The existence of spatial refuges for IG prey has recently been noted for their importance in allowing coexistence. However, reduction in basal prey availability might lead IG prey to leave spatial refuges for greater access to prey, leading to increased IG predation and fewer opportunities for coexistence. We determined how the availability of prey affected space-use patterns of bobcats (Lynx rufus, IG prey) in relation to coyote space-use patterns (Canis latrans, IG predators). We located animals from fall 2007 to spring 2009 and estimated bobcat home ranges and core areas seasonally. For each bobcat relocation, we determined intensity of coyote use, distance to water, small mammal biomass, and mean small mammal biomass of the home range during the season the location was collected. We built generalized linear mixed models and used Akaike Information Criteria to determine which factors best predicted bobcat space use. Coyote intensity was a primary determinant of bobcat core area location. In bobcat home ranges with abundant prey, core areas occurred where coyote use was low, but shifted to areas intensively used by coyotes when prey declined. High spatial variability in basal prey abundance allowed some bobcats to avoid coyotes while at the same time others were forced into more risky areas. Our results suggest that multiple behavioral strategies associated with spatial variation in basal prey abundance likely allow IG prey and IG predators to coexist. ?? 2010 Springer-Verlag.

  13. Are lemmings prey or predators?

    Science.gov (United States)

    Turchin, P.; Oksanen, L.; Ekerholm, P.; Oksanen, T.; Henttonen, H.

    2000-06-01

    Large oscillations in the populations of Norwegian lemmings have mystified both professional ecologists and lay public. Ecologists suspect that these oscillations are driven by a trophic mechanism: either an interaction between lemmings and their food supply, or an interaction between lemmings and their predators. If lemming cycles are indeed driven by a trophic interaction, can we tell whether lemmings act as the resource (`prey') or the consumer (`predator')? In trophic interaction models, peaks of resource density generally have a blunt, rounded shape, whereas peaks of consumer density are sharp and angular. Here we have applied several statistical tests to three lemming datasets and contrasted them with comparable data for cyclic voles. We find that vole peaks are blunt, consistent with their cycles being driven by the interaction with predators. In contrast, the shape of lemming peaks is consistent with the hypothesis that lemmings are functional predators, that is, their cycles are driven by their interaction with food plants. Our findings suggest that a single mechanism, such as interaction between rodents and predators, is unlikely to provide the `universal' explanation of all cyclic rodent dynamics.

  14. Cross-correlation of motor activity signals from dc-magnetoencephalography, near-infrared spectroscopy, and electromyography.

    Science.gov (United States)

    Sander, Tilmann H; Leistner, Stefanie; Wabnitz, Heidrun; Mackert, Bruno-Marcel; Macdonald, Rainer; Trahms, Lutz

    2010-01-01

    Neuronal and vascular responses due to finger movements were synchronously measured using dc-magnetoencephalography (dcMEG) and time-resolved near-infrared spectroscopy (trNIRS). The finger movements were monitored with electromyography (EMG). Cortical responses related to the finger movement sequence were extracted by independent component analysis from both the dcMEG and the trNIRS data. The temporal relations between EMG rate, dcMEG, and trNIRS responses were assessed pairwise using the cross-correlation function (CCF), which does not require epoch averaging. A positive lag on a scale of seconds was found for the maximum of the CCF between dcMEG and trNIRS. A zero lag is observed for the CCF between dcMEG and EMG. Additionally this CCF exhibits oscillations at the frequency of individual finger movements. These findings show that the dcMEG with a bandwidth up to 8 Hz records both slow and faster neuronal responses, whereas the vascular response is confirmed to change on a scale of seconds.

  15. Ultrasonic predator-prey interactions in water-convergent evolution with insects and bats in air?

    Science.gov (United States)

    Wilson, Maria; Wahlberg, Magnus; Surlykke, Annemarie; Madsen, Peter Teglberg

    2013-01-01

    Toothed whales and bats have independently evolved biosonar systems to navigate and locate and catch prey. Such active sensing allows them to operate in darkness, but with the potential cost of warning prey by the emission of intense ultrasonic signals. At least six orders of nocturnal insects have independently evolved ears sensitive to ultrasound and exhibit evasive maneuvers when exposed to bat calls. Among aquatic prey on the other hand, the ability to detect and avoid ultrasound emitting predators seems to be limited to only one subfamily of Clupeidae: the Alosinae (shad and menhaden). These differences are likely rooted in the different physical properties of air and water where cuticular mechanoreceptors have been adapted to serve as ultrasound sensitive ears, whereas ultrasound detection in water have called for sensory cells mechanically connected to highly specialized gas volumes that can oscillate at high frequencies. In addition, there are most likely differences in the risk of predation between insects and fish from echolocating predators. The selection pressure among insects for evolving ultrasound sensitive ears is high, because essentially all nocturnal predation on flying insects stems from echolocating bats. In the interaction between toothed whales and their prey the selection pressure seems weaker, because toothed whales are by no means the only marine predators placing a selection pressure on their prey to evolve specific means to detect and avoid them. Toothed whales can generate extremely intense sound pressure levels, and it has been suggested that they may use these to debilitate prey. Recent experiments, however, show that neither fish with swim bladders, nor squid are debilitated by such signals. This strongly suggests that the production of high amplitude ultrasonic clicks serve the function of improving the detection range of the toothed whale biosonar system rather than debilitation of prey.

  16. Ultrasonic predator-prey interactions in water– convergent evolution with insects and bats in air?

    Directory of Open Access Journals (Sweden)

    Maria eWilson

    2013-06-01

    Full Text Available Toothed whales and bats have independently evolved biosonar systems to navigate and locate and catch prey. Such active sensing allows them to operate in darkness, but with the potential cost of warning prey by the emission of intense ultrasonic signals. At least six orders of nocturnal insects have independently evolved ears sensitive to ultrasound and exhibit evasive maneuvers when exposed to bat calls. Among aquatic prey on the other hand, the ability to detect and avoid ultrasound emitting predators seems to be limited to only one subfamily of Clupeidae: the Alosinae (shad and menhaden. These differences are likely rooted in the different physical properties of air and water where cuticular mechanoreceptors have been adapted to serve as ultrasound sensitive ears, whereas ultrasound detection in water have called for sensory cells mechanically connected to highly specialized gas volumes that can oscillate at high frequencies. In addition, there are most likely differences in the risk of predation between insects and fish from echolocating predators. The selection pressure among insects for evolving ultrasound sensitive ears is high, because essentially all nocturnal predation on flying insects stems from echolocating bats. In the interaction between toothed whales and their prey the selection pressure seems weaker, because toothed whales are by no means the only marine predators placing a selection pressure on their prey to evolve specific means to detect and avoid them.Toothed whales can generate extremely intense sound pressure levels, and it has been suggested that they may use these to debilitate prey. Recent experiments however, show that neither fish with swim bladder, nor squid are debilitated by such signals. This strongly suggests that the production of high amplitude ultrasonic clicks serve the function of improving the detection range of the toothed whale biosonar system rather than debilitation of prey.

  17. Top down and bottom up selection drives variations in frequency and form of a visual signal

    OpenAIRE

    Yeh, Chien-Wei; Blamires, Sean J.; Liao, Chen-Pan; Tso, I.-Min

    2015-01-01

    The frequency and form of visual signals can be shaped by selection from predators, prey or both. When a signal simultaneously attracts predators and prey, selection may favour a strategy that minimizes risks while attracting prey. Accordingly, varying the frequency and form of the silken decorations added to their web may be a way that Argiope spiders minimize predation while attracting prey. Nonetheless, the role of extraneous factors renders the influences of top down and bottom up selecti...

  18. When prey provide more than food: mammalian predators appropriating the refugia of their prey

    Science.gov (United States)

    Bill Zielinski

    2015-01-01

    Some mammalian predators acquire both food and shelter from their prey, by eating them and using the refugia the prey construct. I searched the literature for examples of predators that exhibit this behavior and summarize their taxonomic affiliations, relative sizes, and distributions. I hypothesized that size ratios of species involved in this dynamic would be near 1....

  19. Low-power low-noise analog circuits for on-focal-plane signal processing of infrared sensors

    Science.gov (United States)

    Pain, Bedabrata; Mendis, Sunetra K.; Schober, Robert C.; Nixon, Robert H.; Fossum, Eric R.

    1993-10-01

    On-focal-plane signal processing circuits for enhancement of IR imager performance are presented. To enable the detection of high background IR images, an in-pixel current-mode background suppression scheme is presented. The background suppression circuit consists of a current memory placed in the feedback loop of a CTIA and is designed for a thousand-fold suppression of the background flux, thereby easing circuit design constraints, and assuring BLIP operation even with detectors having large response non-uniformities. For improving the performance of low-background IR imagers, an on-chip column-parallel analog-to-digital converter (ADC) is presented. The design of a 10-bit ADC with 50 micrometers pitch and based on sigma-delta ((Sigma) -(Delta) ) modulation is presented. A novel IR imager readout technique featuring photoelectron counting in the unit cell is presented for ultra-low background applications. The output of the unit cell is a digital word corresponding to the incident flux density and the readout is noise free. The design of low-power (noise, high-gain (> 100,000), small real estate (60 micrometers pitch) self-biased CMOS amplifiers required for photon counting are presented.

  20. Selective Predation of a Stalking Predator on Ungulate Prey.

    Directory of Open Access Journals (Sweden)

    Marco Heurich

    Full Text Available Prey selection is a key factor shaping animal populations and evolutionary dynamics. An optimal forager should target prey that offers the highest benefits in terms of energy content at the lowest costs. Predators are therefore expected to select for prey of optimal size. Stalking predators do not pursue their prey long, which may lead to a more random choice of prey individuals. Due to difficulties in assessing the composition of available prey populations, data on prey selection of stalking carnivores are still scarce. We show how the stalking predator Eurasian lynx (Lynx lynx selects prey individuals based on species identity, age, sex and individual behaviour. To address the difficulties in assessing prey population structure, we confirm inferred selection patterns by using two independent data sets: (1 data of 387 documented kills of radio-collared lynx were compared to the prey population structure retrieved from systematic camera trapping using Manly's standardized selection ratio alpha and (2 data on 120 radio-collared roe deer were analysed using a Cox proportional hazards model. Among the larger red deer prey, lynx selected against adult males-the largest and potentially most dangerous prey individuals. In roe deer lynx preyed selectively on males and did not select for a specific age class. Activity during high risk periods reduced the risk of falling victim to a lynx attack. Our results suggest that the stalking predator lynx actively selects for size, while prey behaviour induces selection by encounter and stalking success rates.

  1. Prey responses to predator chemical cues: disentangling the importance of the number and biomass of prey consumed.

    Directory of Open Access Journals (Sweden)

    Michael W McCoy

    Full Text Available To effectively balance investment in predator defenses versus other traits, organisms must accurately assess predation risk. Chemical cues caused by predation events are indicators of risk for prey in a wide variety of systems, but the relationship between how prey perceive risk in relation to the amount of prey consumed by predators is poorly understood. While per capita predation rate is often used as the metric of relative risk, studies aimed at quantifying predator-induced defenses commonly control biomass of prey consumed as the metric of risk. However, biomass consumed can change by altering either the number or size of prey consumed. In this study we determine whether phenotypic plasticity to predator chemical cues depends upon prey biomass consumed, prey number consumed, or both. We examine the growth response of red-eyed treefrog tadpoles (Agalychnis callidryas to cues from a larval dragonfly (Anax amazili. Biomass consumed was manipulated by either increasing the number of prey while holding individual prey size constant, or by holding the number of prey constant and varying individual prey size. We address two questions. (i Do prey reduce growth rate in response to chemical cues in a dose dependent manner? (ii Does the magnitude of the response depend on whether prey consumption increases via number or size of prey? We find that the phenotypic response of prey is an asymptotic function of prey biomass consumed. However, the asymptotic response is higher when more prey are consumed. Our findings have important implications for evaluating past studies and how future experiments should be designed. A stronger response to predation cues generated by more individual prey deaths is consistent with models that predict prey sensitivity to per capita risk, providing a more direct link between empirical and theoretical studies which are often focused on changes in population sizes not individual biomass.

  2. Are single odorous components of a predator sufficient to elicit defensive behaviors in prey species?

    Directory of Open Access Journals (Sweden)

    Raimund eApfelbach

    2015-07-01

    Full Text Available When exposed to the odor of a sympatric predator, prey animals typically display escape or defensive responses. These phenomena have been well-documented, especially in rodents, when exposed to the odor of a cat, ferret or fox. As a result of these experiments new discussions center on the following questions: 1 is a single volatile compound such as a major or a minor mixture constituent in urine or feces, emitted by the predator sufficient to cause defensive reactions in a potential prey species or 2 is a whole array of odors required to elicit a response and 3 will the relative size or escapability of the prey as compared to the predator influence responsiveness. Most predator-prey studies on this topic have been performed in the laboratory or under semi-natural conditions. Field studies could help to find answers to these questions. Australian mammals are completely naïve towards the introduced placental carnivores. That offers ideal opportunities to analyze in the field the responses of potential prey species to unknown predator odors. During the last decades researchers have accumulated an enormous amount of data exploring the effects of eutherian predator odors on native marsupial mammals. In this review, we will give a survey about the development of olfactory research, chemical signals and their influence on the behavior and - in some cases - physiology of prey species. In addition, we report on the effects of predator odor experiments performed under natural conditions in Australia. When studying all these literature we learned that data gained under controlled laboratory conditions elucidate the role of individual odors on brain structures and ultimately on a comparatively narrow range behaviors. In contrast to single odors odor arrays mimic much more the situation prey animals are confronted to in nature. Therefore, a broad range of methodology — from chemistry to ecology including anatomy, physiology and behavior — is needed to

  3. Use of Fourier-transform infrared spectroscopy to quantify immunoglobulin G concentration and an analysis of the effect of signalment on levels in canine serum.

    Science.gov (United States)

    Seigneur, A; Hou, S; Shaw, R A; McClure, Jt; Gelens, H; Riley, C B

    2015-01-15

    Deficiency in immunoglobulin G (IgG) is associated with an increased susceptibility to infections in humans and animals, and changes in IgG levels occur in many disease states. In companion animals, failure of transfer of passive immunity is uncommonly diagnosed but mortality rates in puppies are high and more than 30% of these deaths are secondary to septicemia. Currently, radial immunodiffusion (RID) and enzyme-linked immunosorbent assays are the most commonly used methods for quantitative measurement of IgG in dogs. In this study, a Fourier-transform infrared spectroscopy (FTIR) assay for canine serum IgG was developed and compared to the RID assay as the reference standard. Basic signalment data and health status of the dogs were also analyzed to determine if they correlated with serum IgG concentrations based on RID results. Serum samples were collected from 207 dogs during routine hematological evaluation, and IgG concentrations determined by RID. The FTIR assay was developed using partial least squares regression analysis and its performance evaluated using RID assay as the reference test. The concordance correlation coefficient was 0.91 for the calibration model data set and 0.85 for the prediction set. A Bland-Altman plot showed a mean difference of -89 mg/dL and no systematic bias. The modified mean coefficient of variation (CV) for RID was 6.67%, and for FTIR was 18.76%. The mean serum IgG concentration using RID was 1943 ± 880 mg/dL based on the 193 dogs with complete signalment and health data. When age class, gender, breed size and disease status were analyzed by multivariable ANOVA, dogs < 2 years of age (p = 0.0004) and those classified as diseased (p = 0.03) were found to have significantly lower IgG concentrations than older and healthy dogs, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Microbiological survey of birds of prey pellets.

    Science.gov (United States)

    Dipineto, Ludovico; Bossa, Luigi Maria De Luca; Pace, Antonino; Russo, Tamara Pasqualina; Gargiulo, Antonio; Ciccarelli, Francesca; Raia, Pasquale; Caputo, Vincenzo; Fioretti, Alessandro

    2015-08-01

    A microbiological survey of 73 pellets collected from different birds of prey species housed at the Wildlife Rescue and Rehabilitation Center of Napoli (southern Italy) was performed. Pellets were analyzed by culture and biochemical methods as well as by serotyping and polymerase chain reaction. We isolated a wide range of bacteria some of them also pathogens for humans (i.e. Salmonella enterica serotype Typhimurium, Campylobacter coli, Escherichia coli O serogroups). This study highlights the potential role of birds of prey as asymptomatic carriers of pathogenic bacteria which could be disseminated in the environment not only through the birds of prey feces but also through their pellets. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Prey capture by freely swimming flagellates

    Science.gov (United States)

    Andersen, Anders; Dolger, Julia; Nielsen, Lasse Tor; Kiorboe, Thomas

    2017-11-01

    Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. Here, we explore the dependence of swimming kinematics and prey clearance rate on flagellar arrangement and determine optimal flagellar arrangements and essential trade-offs. To describe near-cell flows around freely swimming flagellates we consider a model in which the cell is represented by a no-slip sphere and each flagellum by a point force. For uniflagellates pulled by a single flagellum the model suggests that a long flagellum favors fast swimming, whereas high clearance rate is favored by a very short flagellum. For biflagellates with both a longitudinal and a transversal flagellum we explore the helical swimming kinematics and the prey capture sites. We compare our predictions with observations of swimming kinematics, prey capture, and flows around common marine flagellates. The Centre for Ocean Life is a VKR Centre of Excellence supported by the Villum Foundation.

  6. Non-webbuilding spiders: prey specialists or generalists?

    Science.gov (United States)

    Nentwig, Wolfgang

    1986-07-01

    Feeding experiments were performed with seven species of non-webbuilding spiders and a variety of prey taxa. Some species were generally polyphagous whereas other spiders restricted their prey to a few groups. At one end of the spectrum of prey specialization the thomisid Misumena vatia is limited to a few taxa of possible prey (Table 1). The literature of prey records of non-webbuilding spiders is reviewed (Table 2) with special emphasis on oligophagous or monophagous spiders. Monophagous spiders are generally rare and have specialized on only a few prey taxa: social insects (ants, bees, termites) and spiders.

  7. Interactive effects of prey refuge and additional food for predator in a diffusive predator-prey system

    DEFF Research Database (Denmark)

    Chakraborty, Subhendu; Tiwari, P. K.; Sasmal, S.K.

    2017-01-01

    a predator-prey system with prey refuge and additional food for predator apart from the focal prey in the presence of diffusion. Our main aim is to study the interactive effects of prey refuge and additional food on the system dynamics and especially on the controllability of prey (pest). Different types......Additional food for predators has been considered as one of the best established techniques in integrated pest management and biological conservation programs. In natural systems, there are several other factors, e.g., prey refuge, affect the success of pest control. In this paper, we analyze...... of Turing patterns such as stripes, spots, holes, and mixtures of them are obtained. It is found that the supply of additional food to the predator is unable to control the prey (pest) population when prey refuge is high. Moreover, when both prey refuge and additional food are low, spatial distribution...

  8. Design and characterization of a mixed-signal PCB for digital-to-analog conversion in a modular and scalable infrared scene projector

    Science.gov (United States)

    Benedict, Jacob

    Infra-red (IR) sensors have proven instrumental in a wide variety of fields from military to industrial applications. The proliferation of IR sensors has spawned an intense push for technologies that can test and calibrate the multitudes of IR sensors. One such technology, IR scene projection (IRSP), provides an inexpensive and safe method for the testing of IR sensor devices. Previous efforts have been conducted to develop IRSPs based on super-lattice light emitting diodes (SLEDS). A single-color 512x512 SLEDs system has been developed, produced, and tested as documented in Corey Lange's Master's thesis, and a GOMAC paper by Rodney McGee [1][2]. Current efforts are being undergone to develop a two-color 512x512 SLEDs system designated (TCSA). The following thesis discusses the design and implementation of a custom printed circuit board (PCB), known as the FMC 4DAC, that contains both analog and digital signals. Utilizing two 16-bit digital-to-analog converters (DAC) the purpose of the board is to provide four analog current output channels for driving the TCSA system to a maximum frame rate of 1 kHz. In addition, the board supports a scalable TCSA system architecture. Several copies of the board can be run in parallel to achieve a range of analog channels between 4 and 32.

  9. Classification of functional near-infrared spectroscopy signals corresponding to the right- and left-wrist motor imagery for development of a brain-computer interface.

    Science.gov (United States)

    Naseer, Noman; Hong, Keum-Shik

    2013-10-11

    This paper presents a study on functional near-infrared spectroscopy (fNIRS) indicating that the hemodynamic responses of the right- and left-wrist motor imageries have distinct patterns that can be classified using a linear classifier for the purpose of developing a brain-computer interface (BCI). Ten healthy participants were instructed to imagine kinesthetically the right- or left-wrist flexion indicated on a computer screen. Signals from the right and left primary motor cortices were acquired simultaneously using a multi-channel continuous-wave fNIRS system. Using two distinct features (the mean and the slope of change in the oxygenated hemoglobin concentration), the linear discriminant analysis classifier was used to classify the right- and left-wrist motor imageries resulting in average classification accuracies of 73.35% and 83.0%, respectively, during the 10s task period. Moreover, when the analysis time was confined to the 2-7s span within the overall 10s task period, the average classification accuracies were improved to 77.56% and 87.28%, respectively. These results demonstrate the feasibility of an fNIRS-based BCI and the enhanced performance of the classifier by removing the initial 2s span and/or the time span after the peak value. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  10. Can species-specific prey responses to chemical cues explain prey susceptibility to predation?

    Science.gov (United States)

    Šmejkal, Marek; Ricard, Daniel; Sajdlová, Zuzana; Čech, Martin; Vejřík, Lukáš; Blabolil, Petr; Vejříková, Ivana; Prchalová, Marie; Vašek, Mojmír; Souza, Allan T; Brönmark, Christer; Peterka, Jiří

    2018-05-01

    The perception of danger represents an essential ability of prey for gaining an informational advantage over their natural enemies. Especially in complex environments or at night, animals strongly rely on chemoreception to avoid predators. The ability to recognize danger by chemical cues and subsequent adaptive responses to predation threats should generally increase prey survival. Recent findings suggest that European catfish ( Silurus glanis ) introduction induce changes in fish community and we tested whether the direction of change can be attributed to differences in chemical cue perception. We tested behavioral response to chemical cues using three species of freshwater fish common in European water: rudd ( Scardinius erythrophthalmus ), roach ( Rutilus rutilus ), and perch ( Perca fluviatilis ). Further, we conducted a prey selectivity experiment to evaluate the prey preferences of the European catfish. Roach exhibited the strongest reaction to chemical cues, rudd decreased use of refuge and perch did not alter any behavior in the experiment. These findings suggest that chemical cue perception might be behind community data change and we encourage collecting more community data of tested prey species before and after European catfish introduction to test the hypothesis. We conclude that used prey species can be used as a model species to verify whether chemical cue perception enhances prey survival.

  11. Predator-prey encounters in turbulent waters

    DEFF Research Database (Denmark)

    Mann, J.; Ott, Søren; Pécseli, H.L.

    2002-01-01

    With reference to studies of predator-prey encounters in turbulent waters, we demonstrate the feasibility of an experimental method for investigations of particle fluxes to an absorbing surface in turbulent flows. A laboratory experiment is carried out, where an approximately homogeneous and isot......With reference to studies of predator-prey encounters in turbulent waters, we demonstrate the feasibility of an experimental method for investigations of particle fluxes to an absorbing surface in turbulent flows. A laboratory experiment is carried out, where an approximately homogeneous...

  12. Wild North Island Robins (Petroica longipes respond to Prey Animacy

    Directory of Open Access Journals (Sweden)

    Alexis Garland

    2014-08-01

    Full Text Available North Island robins of New Zealand are a food hoarding species, which is unique in that they almost exclusively cache highly perishable hunted insects for later retrieval. In order to do so, they either kill and dismember or paralyze their prey for caching, depending on the prey size and kind. The present study comprises two experiments, using a Violation of Expectancy (VoE paradigm to examine variation in search behavior response to different prey conditions. The first experiment presents three different types of prey (mealworms, earthworms and locusts in expected (present and unexpected (absent conditions. The second experiment presents prey in varying states of animacy (alive and whole, dead and whole, dead and halved, and an inanimate stick and reveals prey in expected (same state or unexpected (differing state conditions. While robins did not respond with differential search times to different types of unexpectedly missing prey in Experiment 1, in Experiment 2 robins searched longer in conditions where prey was found in a differing state of animacy than initially shown. Robins also searched longer for prey when immediately consuming retrieved prey than when caching retrieved prey. Results indicate that North Island robins may be sensitive to prey animacy upon storage and retrieval of insect prey; such information could play a role in storage, pilfering and retrieval strategies of such a perishable food source.

  13. Prey switching behaviour in the planktonic copepod Acartia tonsa

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Saiz, E.; Viitasalo, M.

    1996-01-01

    The copepod Acartia tonsa has 2 different prey encounter strategies. It can generate a feeding current to encounter and capture immobile prey (suspension feeding) or it can sink slowly and perceive motile prey by means of mechanoreceptors on the antennae (ambush feeding). We hypothesized that A....... tonsa adopts the feeding mode that generates the highest energy intake rate; i.e. that prey selection changes according to the relative concentrations of alternative prey (prey switching) and that the copepods spend disproportionately more time in the feeding mode that provides the greatest reward...... be captured by suspension feeding copepods. Finally, we demonstrate that turbulence favours the selection of ciliates as prey. We suggest that prey switching by copepods may provide survival windows for microzooplankters during blooms of net phytoplankton because predation pressure from the copepods...

  14. Models of prey capture in larval fish

    NARCIS (Netherlands)

    Drost, M.R.

    1986-01-01

    The food uptake of larval carp and pike is described from high speed movies with synchronous lateral and ventral views.

    During prey intake by larval fishes the velocities of the created suction flow are high relative to their own size: 0.3 m/s for carp larvae of 6

  15. Lake Ontario benthic prey fish assessment, 2015

    Science.gov (United States)

    Weidel, Brian C.; Walsh, Maureen; Holden, Jeremy P.; Connerton, Michael J.

    2016-01-01

    Benthic prey fishes are a critical component of the Lake Ontario food web, serving as energy vectors from benthic invertebrates to native and introduced piscivores. Since the late 1970’s, Lake Ontario benthic prey fish status was primarily assessed using bottom trawl observations confined to the lake’s south shore, in waters from 8 – 150 m (26 – 492 ft). In 2015, the Benthic Prey Fish Survey was cooperatively adjusted and expanded to address resource management information needs including lake-wide benthic prey fish population dynamics. Effort increased from 55 bottom trawl sites to 135 trawl sites collected in depths from 8 - 225m (26 – 738 ft). The spatial coverage of sampling was also expanded and occurred in all major lake basins. The resulting distribution of tow depths more closely matched the available lake depth distribution. The additional effort illustrated how previous surveys were underestimating lake-wide Deepwater Sculpin, Myoxocephalus thompsonii, abundance by not sampling in areas of highest density. We also found species richness was greater in the new sampling sites relative to the historic sites with 11 new fish species caught in the new sites including juvenile Round Whitefish, Prosopium cylindraceum, and Mottled sculpin, Cottus bairdii. Species-specific assessments found Slimy Sculpin, Cottus cognatus abundance increased slightly in 2015 relative to 2014, while Deepwater Sculpin and Round Goby, Neogobius melanostomus, dramatically increased in 2015, relative to 2014. The cooperative, lake-wide Benthic Prey Fish Survey expanded our understanding of benthic fish population dynamics and habitat use in Lake Ontario. This survey’s data and interpretations influence international resource management decision making, such as informing the Deepwater Sculpin conservation status and assessing the balance between sport fish consumption and prey fish populations. Additionally a significant Lake Ontario event occurred in May 2015 when a single

  16. Killer whale prey - Determining prey selection by southern resident killer whales (SRKW)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Prey selectivity by southern resident killer whales is being determined by analyses of fish scales and tissue from predation events and feces. Information on killer...

  17. Prey-Predator Model with a Nonlocal Bistable Dynamics of Prey

    Directory of Open Access Journals (Sweden)

    Malay Banerjee

    2018-03-01

    Full Text Available Spatiotemporal pattern formation in integro-differential equation models of interacting populations is an active area of research, which has emerged through the introduction of nonlocal intra- and inter-specific interactions. Stationary patterns are reported for nonlocal interactions in prey and predator populations for models with prey-dependent functional response, specialist predator and linear intrinsic death rate for predator species. The primary goal of our present work is to consider nonlocal consumption of resources in a spatiotemporal prey-predator model with bistable reaction kinetics for prey growth in the absence of predators. We derive the conditions of the Turing and of the spatial Hopf bifurcation around the coexisting homogeneous steady-state and verify the analytical results through extensive numerical simulations. Bifurcations of spatial patterns are also explored numerically.

  18. SRKW summer prey - Prey species and stock specific consumption estimates for SRKW in their summer range

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Southern Resident Killer Whales (SRKW) are listed as a Distinct Population Segment under the Endangered Species Act. Data concerning their prey species and stock...

  19. Swimming and escape behavior of copepod nauplii: implications for predator-prey interactions among copepods

    DEFF Research Database (Denmark)

    Titelman, Josefin

    2001-01-01

    This study focuses on how prey behavior may affect predation risk through encounter rates and the escape success of the prey given an encounter. Temora longicornis nauplii require stronger hydrodynamic signals to elicit escape than Acartia tonsa nauplii (critical fluid deformation rates, Delta......* of 2.8 to 4.0 and 1.2 to 2.5 s(-1), respectively) suggesting that T. longicornis may be more susceptible to predation. Quantification of naupliar motility behavior and subsequent estimation of the hydrodynamic signals which the nauplii generate suggest that an adult female Centropages typicus may......, the behavior of A. tonsa acts predominantly at the post-encounter stage where its sensitivity to hydrodynamic signals (i,e., low Delta*) effectively compensates for the high predator encounter rate generated by its motility....

  20. Prey aggregation is an effective olfactory predator avoidance strategy

    Directory of Open Access Journals (Sweden)

    Asa Johannesen

    2014-05-01

    Full Text Available Predator–prey interactions have a major effect on species abundance and diversity, and aggregation is a well-known anti-predator behaviour. For immobile prey, the effectiveness of aggregation depends on two conditions: (a the inability of the predator to consume all prey in a group and (b detection of a single large group not being proportionally easier than that of several small groups. How prey aggregation influences predation rates when visual cues are restricted, such as in turbid water, has not been thoroughly investigated. We carried out foraging (predation experiments using a fish predator and (dead chironomid larvae as prey in both laboratory and field settings. In the laboratory, a reduction in visual cue availability (in turbid water led to a delay in the location of aggregated prey compared to when visual cues were available. Aggregated prey suffered high mortality once discovered, leading to better survival of dispersed prey in the longer term. We attribute this to the inability of the dead prey to take evasive action. In the field (where prey were placed in feeding stations that allowed transmission of olfactory but not visual cues, aggregated (large groups and semi-dispersed prey survived for longer than dispersed prey—including long term survival. Together, our results indicate that similar to systems where predators hunt using vision, aggregation is an effective anti-predator behaviour for prey avoiding olfactory predators.

  1. Competition and Dispersal in Predator-Prey Waves

    NARCIS (Netherlands)

    Savill, N.J.; Hogeweg, P.

    1998-01-01

    Dispersing predators and prey can exhibit complex spatio-temporal wave-like patterns if the interactions between them cause oscillatory dynamics. We study the effect of these predator- prey density waves on the competition between prey populations and between predator popu- lations with different

  2. Predatory mites avoid ovipositing near counter-attacking prey

    NARCIS (Netherlands)

    Faraji, F.; Janssen, A.; Sabelis, M.W.

    2001-01-01

    Attacking prey is not without risk; predators may endure counterattackby the prey. Here, we study the oviposition behaviour of a predatory mite(Iphiseius degenerans) in relation to its prey, thewesternflower thrips (Frankliniella occidentalis). This thrips iscapable of killing the eggs of the

  3. Prey perception in feeding-current feeding copepods

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Goncalves, Rodrigo J.; Florian Couespel, Damien

    2016-01-01

    We reply to the comments of Paffenhöfer and Jiang () who argues that remote chemical prey perception is necessary for feeding-current feeding copepods to fulfill their nutritional requirements in a dilute ocean, that remote chemical prey detection may only be observed at very low prey concentrati......We reply to the comments of Paffenhöfer and Jiang () who argues that remote chemical prey perception is necessary for feeding-current feeding copepods to fulfill their nutritional requirements in a dilute ocean, that remote chemical prey detection may only be observed at very low prey...... cells have short intense leakage burst, only a very small fraction of prey cells would be available to the copepod at any instance in time and, thus would be inefficient at low prey concentration. Finally, we report a few new observations of prey capture in two species of copepods, Temora longicornis...... and Centropages hamatus, offered a 45-μm sized dinoflagellate at very low concentration. The observed short prey detection distances, up to a few prey cell radii, are consistent with mechanoreception and we argue briefly that near-field mechanoreception is the most likely and common prey perception mechanism...

  4. The functional response to prey density in an acarine system

    NARCIS (Netherlands)

    Fransz, H.G.

    1974-01-01

    Predacious mites are considered to be important natural enemies of phytophagous mites. Their efficiency in the natural control of prey populations depends on the relationships of the number of prey killed per predator per time unit and the oviposition rate on the one hand and prey density on the

  5. Vigilance task-related change in brain functional connectivity as revealed by wavelet phase coherence analysis of near-infrared spectroscopy signals

    Directory of Open Access Journals (Sweden)

    Wang Wei

    2016-08-01

    Full Text Available This study aims to assess the vigilance task-related change in connectivity in healthy adults using wavelet phase coherence (WPCO analysis of near-infrared spectroscopy signals (NIRS. NIRS is a non-invasive neuroimaging technique for assessing brain activity. Continuous recordings of the NIRS signals were obtained from the prefrontal cortex (PFC and sensorimotor cortical areas of 20 young healthy adults (24.9±3.3 years during a 10-min resting state and a 20-min vigilance task state. The vigilance task was used to simulate driving mental load by judging three random numbers (i.e., whether odd numbers. The task was divided into two sessions: the first 10 minutes (Task t1 and the second 10 minutes (Task t2. The WPCO of six channel pairs were calculated in five frequency intervals: 0.6–2 Hz (I, 0.145–0.6 Hz (II, 0.052–0.145 Hz (III, 0.021–0.052 Hz (IV, and 0.0095–0.021 Hz (V. The significant WPCO formed global connectivity (GC maps in intervals I and II and functional connectivity (FC maps in intervals III to V. Results show that the GC levels in interval I and FC levels in interval III were significantly lower in the Task t2 than in the resting state (p < 0.05, particularly between the left PFC and bilateral sensorimotor regions. Also, the reaction time shows an increase in Task t2 compared with that in Task t1. However, no significant difference in WPCO was found between Task t1 and resting state. The results showed that the change in FC at the range of 0.6-2 Hz was not attributed to the vigilance task pe se, but the interaction effect of vigilance task and time factors. The findings suggest that the decreased attention level might be partly attributed to the reduced GC levels between the left prefrontal region and sensorimotor area. The present results provide a new insight into the vigilance task-related brain activity.

  6. Turing-Hopf bifurcations in a predator-prey model with herd behavior, quadratic mortality and prey-taxis

    Science.gov (United States)

    Liu, Xia; Zhang, Tonghua; Meng, Xinzhu; Zhang, Tongqian

    2018-04-01

    In this paper, we propose a predator-prey model with herd behavior and prey-taxis. Then, we analyze the stability and bifurcation of the positive equilibrium of the model subject to the homogeneous Neumann boundary condition. By using an abstract bifurcation theory and taking prey-tactic sensitivity coefficient as the bifurcation parameter, we obtain a branch of stable nonconstant solutions bifurcating from the positive equilibrium. Our results show that prey-taxis can yield the occurrence of spatial patterns.

  7. Are all prey created equal? A review and synthesis of differential predation on prey in substandard condition

    Science.gov (United States)

    Mesa, Matthew G.; Poe, Thomas P.; Gadomski, Dena M.; Petersen, James H.

    1994-01-01

    Our understanding of predator-prey interactions in fishes has been influenced largely by research assuming that the condition of the participants is normal. However, fish populations today often reside in anthropogenically altered environments and are subjected to many kinds of stressors, which may reduce their ecological performance by adversely affecting their morphology, physiology, or behaviour. One consequence is that either the predator or prey, or both, may be in a substandard condition at the time of an interaction. We reviewed the literature on predator-prey interactions in fishes where substandard prey were used as experimental groups. Although most of this research indicates that such prey are significantly more vulnerable to predation, prey condition has rarely been considered in ecological theory regarding predator-prey interactions. The causal mechanisms for increased vulnerability of substandard prey to predation include a failure to detect predators, lapses in decision-making, poor fast-start performance, inability to shoal effectively, and increased prey conspicuousness. Despite some problems associated with empirical predator-prey studies using substandard prey, their results can have theoretical and applied uses, such as in ecological modelling or justification of corrective measures to be implemented in the wild. There is a need for more corroborative field experimentation, a better understanding of the causal mechanisms behind differential predation, and increased incorporation of prey condition into the research of predator-prey modellers and theoreticians. If the concept of prey condition is considered in predator-prey interactions, our understanding of how such interactions influence the structure and dynamics of fish communities is likely to change, which should prove beneficial to aquatic ecosystems.

  8. Predatory functional response and prey choice identify predation differences between native/invasive and parasitised/unparasitised crayfish.

    Science.gov (United States)

    Haddaway, Neal R; Wilcox, Ruth H; Heptonstall, Rachael E A; Griffiths, Hannah M; Mortimer, Robert J G; Christmas, Martin; Dunn, Alison M

    2012-01-01

    Invasive predators may change the structure of invaded communities through predation and competition with native species. In Europe, the invasive signal crayfish Pacifastacus leniusculus is excluding the native white clawed crayfish Austropotamobius pallipes. This study compared the predatory functional responses and prey choice of native and invasive crayfish and measured impacts of parasitism on the predatory strength of the native species. Invasive crayfish showed a higher (>10%) prey (Gammarus pulex) intake rate than (size matched) natives, reflecting a shorter (16%) prey handling time. The native crayfish also showed greater selection for crustacean prey over molluscs and bloodworm, whereas the invasive species was a more generalist predator. A. pallipes parasitised by the microsporidian parasite Thelohania contejeani showed a 30% reduction in prey intake. We suggest that this results from parasite-induced muscle damage, and this is supported by a reduced (38%) attack rate and increased (30%) prey handling time. Our results indicate that the per capita (i.e., functional response) difference between the species may contribute to success of the invader and extinction of the native species, as well as decreased biodiversity and biomass in invaded rivers. In addition, the reduced predatory strength of parasitized natives may impair their competitive abilities, facilitating exclusion by the invader.

  9. Non-neuronal evoked and spontaneous hemodynamic changes in the anterior temporal region of the human head may lead to misinterpretations of functional near-infrared spectroscopy signals.

    Science.gov (United States)

    Zimeo Morais, Guilherne Augusto; Scholkmann, Felix; Balardin, Joana Bisol; Furucho, Rogério Akira; de Paula, Renan Costa Vieira; Biazoli, Claudinei Eduardo; Sato, João Ricardo

    2018-01-01

    Several functional near-infrared spectroscopy (fNIRS) studies report their findings based on changes of a single chromophore, usually concentration changes of oxygenated hemoglobin ([[Formula: see text

  10. Neuromuscular control of prey capture in frogs.

    OpenAIRE

    Nishikawa, K C

    1999-01-01

    While retaining a feeding apparatus that is surprisingly conservative morphologically, frogs as a group exhibit great variability in the biomechanics of tongue protraction during prey capture, which in turn is related to differences in neuromuscular control. In this paper, I address the following three questions. (1) How do frog tongues differ biomechanically? (2) What anatomical and physiological differences are responsible? (3) How is biomechanics related to mechanisms of neuromuscular cont...

  11. Molecular prey identification in Central European piscivores

    OpenAIRE

    Thalinger, Bettina; Oehm, Johannes; Mayr, Hannes; Obwexer, Armin; Zeisler, Christiane; Traugott, Michael

    2015-01-01

    Abstract Diet analysis is an important aspect when investigating the ecology of fish?eating animals and essential for assessing their functional role in food webs across aquatic and terrestrial ecosystems. The identification of fish remains in dietary samples, however, can be time?consuming and unsatisfying using conventional morphological analysis of prey remains. Here, we present a two?step multiplex PCR system, comprised of six assays, allowing for rapid, sensitive and specific detection o...

  12. Infomechanical specializations for prey capture in knifefish

    Science.gov (United States)

    Maciver, Malcolm; Patankar, Neelesh; Curet, Oscar; Shirgaonkar, Anup

    2007-11-01

    How does an animal's mechanics and its information acquisition system work together to solve crucial behavioral tasks? We examine this question for the black ghost weakly electric knifefish (Apteronotus albifrons), which is a leading model system for the study of sensory processing in vertebrates. These animals hunt at night by detecting perturbations of a self-generated electric field caused by prey. While the fish searches for prey, it pitches at 30 . Fully resolved Navier-Stokes simulations of their swimming, which occurs through undulations of a long ribbon-like fin along the bottom edge of the body, indicates that this configuration enables maximal thrust while minimizing pitch moment. However, pitching the body also increases drag. Our analysis of the sensory volume for detection of prey shows this volume to be similar to a cylinder around the body. Thus, pitching the body enables a greater swept volume of scanned fluid. Examining the mechanical and information acquisition demands on the animal in this task gives insight into how these sometimes conflicting demands are resolved.

  13. Are single odorous components of a predator sufficient to elicit defensive behaviors in prey species?

    Science.gov (United States)

    Apfelbach, Raimund; Parsons, Michael H; Soini, Helena A; Novotny, Milos V

    2015-01-01

    When exposed to the odor of a sympatric predator, prey animals typically display escape or defensive responses. These phenomena have been well-documented, especially in rodents, when exposed to the odor of a cat, ferret, or fox. As a result of these experiments new discussions center on the following questions: (1) is a single volatile compound such as a major or a minor mixture constituent in urine or feces, emitted by the predator sufficient to cause defensive reactions in a potential prey species or (2) is a whole array of odors required to elicit a response and (3) will the relative size or escapability of the prey as compared to the predator influence responsiveness. Most predator-prey studies on this topic have been performed in the laboratory or under semi-natural conditions. Field studies could help to find answers to these questions. Australian mammals are completely naïve toward the introduced placental carnivores. That offers ideal opportunities to analyze in the field the responses of potential prey species to unknown predator odors. During the last decades researchers have accumulated an enormous amount of data exploring the effects of eutherian predator odors on native marsupial mammals. In this review, we will give a survey about the development of olfactory research, chemical signals and their influence on the behavior and-in some cases-physiology of prey species. In addition, we report on the effects of predator odor experiments performed under natural conditions in Australia. When studying all these literature we learned that data gained under controlled laboratory conditions elucidate the role of individual odors on brain structures and ultimately on a comparatively narrow range behaviors. In contrast to single odors odor arrays mimic much more the situation prey animals are confronted to in nature. Therefore, a broad range of methodology-from chemistry to ecology including anatomy, physiology, and behavior-is needed to understand all the

  14. Slow food: insect prey and chitin induce phytohormone accumulation and gene expression in carnivorous Nepenthes plants.

    Science.gov (United States)

    Yilamujiang, Ayufu; Reichelt, Michael; Mithöfer, Axel

    2016-08-01

    Carnivorous Nepenthes plants use modified leaves forming pitfall traps to capture and digest prey, mainly insects, for additional nutrient supply. These traps, so called pitchers, contain a plant-derived fluid composed of many hydrolytic enzymes and defence-related proteins. In this study, the prey-induced induction of corresponding genes of those proteins and a role for phytohormones in this process was analysed. Tissue from insect prey-fed, chitin- and phytohormone-challenged pitchers was harvested and analysed for selected gene expressions by a quantitative PCR technique. Phytohormone levels were determined by LC-MS/MS. Nepenthesin proteolytic activities were measured in the digestive fluid using a fluorescence substrate. Insect prey in the pitchers induced the accumulation of phytohormones such as jasmonates as well as the transcription of studied genes encoding a chitinase 3 and a protease (nepenthesin I), whereas a defence-related protein (PR-1) gene was not induced. Treatment with chitin as a component of the insects' exoskeleton triggered the accumulation of jasmonates, the expression of nepenthesin I and chitinase 3 genes similar to jasmonic acid treatment, and induced protease activity in the fluid. All detectable responses were slowly induced. The results suggest that upon insect prey catch a sequence of signals is initiated: (1) insect-derived chitin, (2) jasmonate as endogenous phytohormone signal, (3) the induction of digestive gene expression and (4) protein expression. This resembles a similar hierarchy of events as described from plant pathogen/herbivore interactions, supporting the idea that carnivory evolved from plant defences. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. Prey-predator dynamics with prey refuge providing additional food to predator

    International Nuclear Information System (INIS)

    Ghosh, Joydev; Sahoo, Banshidhar; Poria, Swarup

    2017-01-01

    Highlights: • The effects of interplay between prey refugia and additional food are reported. • Hopf bifurcation conditions are derived analytically. • Existence of unique limit cycle is shown analytically. • Predator extinction may be possible at very high prey refuge ecological systems. - Abstract: The impacts of additional food for predator on the dynamics of a prey-predator model with prey refuge are investigated. The equilibrium points and their stability behaviours are determined. Hopf bifurcation conditions are derived analytically. Most significantly, existence conditions for unique stable limit cycle in the phase plane are shown analytically. The analytical results are in well agreement with the numerical simulation results. Effects of variation of refuge level as well as the variation of quality and quantity of additional food on the dynamics are reported with the help of bifurcation diagrams. It is found that high quality and high quantity of additional food supports oscillatory coexistence of species. It is observed that predator extinction possibility in high prey refuge ecological systems may be removed by supplying additional food to predator population. The reported theoretical results may be useful to conservation biologist for species conservation in real world ecological systems.

  16. Prey preferences and prey acceptance in juvenile Brown Treesnakes (Boiga irregularis)

    Science.gov (United States)

    Lardner, Bjorn; Savidge, Julie A.; Rodda, Gordon H.; Reed, Robert N.

    2009-01-01

    On the Pacific island of Guam, control of the invasive Brown Treesnake (Boiga irregularis) relies largely on methods that use mice as bait. Juvenile B. irregularis feed primarily on lizards and their eggs, but little is known about their prey preference. We conducted an experiment to investigate preferences for, and acceptance of, dead geckos, skinks, and neonatal mice, in juvenile B. irregularis ranging from 290 mm to ca. 700 mm snout-vent length (SVL). Snakes of all sizes showed a preference for geckos over skinks and neonatal mice. Geckos were the first prey chosen in 87% of 224 initial trials (56 snakes subjected to four trials each; 33% would be expected from a random choice). The smallest snakes had the most pronounced preference. Although many of the snakes accepted neonatal mice and/or skinks, some snakes of all sizes were reluctant to feed on anything but geckos, especially when well fed. We also addressed the hypothesis that repeated encounters with a particular prey type increase a snake's preference for that prey. Our study does not support this hypothesis. Our results suggest that control methods relying solely on rodent bait may be inefficient for targeting snakes < 700 mm SVL and that individual heterogeneity in prey preference may cause a significant part of this juvenile cohort to be completely refractory to capture with rodent bait, even if the bait is dead and small enough to be readily swallowed.

  17. Educated predators make strategic decisions to eat defended prey according to their toxin content

    OpenAIRE

    Craig A. Barnett; John Skelhorn; Melissa Bateson; Candy Rowe

    2012-01-01

    Animals often eat foods containing toxins to benefit from the nutrients that they contain. Understanding how animals balance the costs of eating toxins with the benefits of gaining nutrients is important for understanding the evolution of antipredator defenses, particularly aposematism and mimicry. In this study, we tested whether predators could learn to use color signals to make strategic decisions about when to include prey that varied in their toxin content in their diets. We gave Europea...

  18. The role of methyl salicylate in prey searching behavior of the predatory mite phytoseiulus persimilis.

    Science.gov (United States)

    De Boer, Jetske G; Dicke, Marcel

    2004-02-01

    Many carnivorous arthropods use herbivore-induced plant volatiles to locate their prey. These plant volatiles are blends of up to hundreds of compounds. It is often unknown which compounds in such a complex volatile blend represent the signal to the foraging carnivore. We studied the role of methyl salicylate (MeSA) as part of the volatile blend in the foraging behavior of the predatory mite Phytoseiulus persimilis by using a Y-tube olfactometer. MeSA is one of the compounds released by lima bean, infested with Tetranychus urticae--a prey species of the predatory mite. MeSA attracted satiated predatory mites in a dose-dependent way with optimum attraction at a dose of 0.2 microg. Predatory mites did not discriminate between a prey-induced lima bean volatile blend (that contains MeSA) and a prey-induced volatile blend to which an extra amount of synthetic MeSA had been added. However, they preferred a MeSA-containing volatile blend (induced by T. urticae) to an otherwise similar but MeSA-free blend (induced by jasmonic acid). Adding synthetic MeSA to the MeSA-free blend significantly increased the mites' choice for this odor, suggesting an important role for MeSA. This study is a new step toward unraveling the role of herbivore-induced plant volatiles in the foraging behavior of predatory arthropods.

  19. SOHO hunts elusive solar prey

    Science.gov (United States)

    1995-10-01

    limited by inclement weather conditions and atmospheric distortion of the Sun’s signal, and of course they cannot observe the Sun at night. Although the weather problem has been removed in orbit around the Earth, observations are still periodically interrupted when an Earth-orbiting spacecraft enters our planet’s shadow. In contrast, SOHO will provide the first long, clean uninterrupted views of the Sun. Science Objectives SOHO will look beyond the visible soar disk, observing through new windows from the centre of the Sun to the Earth. It will examine three regions - the hidden interior of the Sun, the hot transparent solar atmosphere, and the eternal solar wind of charged particles and magnetic fields that continuously flow outward from the Sun. The twelve instruments on board SOHO are designed to study one or two of these regions in a different, yet complimentary way. Their combined data will link events in the Sun’s atmosphere and solar wind changes taking place deep within the Sun. The SOHO mission has three principle scientific objectives: 1. Study of the structure and dynamics of the solar interior 2. Study of the heating mechanisms of the Sun's million-degree atmosphere, or solar corona 3. Investigation of the solar wind, its origin and its acceleration processes. "Never before have solar physicists had the opportunity to work with such a comprehensive observatory giving them access literally to the whole Sun", said Martin C. E. Huber, the Head of ESA's Space Science Department. Taking the pulse of the Sun SOHO wil illuminate the unseen depths of the Sun by recording widespread throbbing motions of the Sun's visible "surface", or photosphere. These oscillations are caused by sounds that are trapped inside the Sun. On striking the surface and rebounding back down, the sound waves cause the gases there to move up and down. Sound waves that penetrate deep within the Sun produce global surface oscillations with longer periods of up to a few hours; smaller

  20. Interspecific variation in prey capture behavior by co-occurring Nepenthes pitcher plants: evidence for resource partitioning or sampling-scheme artifacts?

    Science.gov (United States)

    Chin, Lijin; Chung, Arthur Y C; Clarke, Charles

    2014-01-01

    Pitcher plants of the genus Nepenthes capture a wide range of arthropod prey for nutritional benefit, using complex combinations of visual and olfactory signals and gravity-driven pitfall trapping mechanisms. In many localities throughout Southeast Asia, several Nepenthes different species occur in mixed populations. Often, the species present at any given location have strongly divergent trap structures and preliminary surveys indicate that different species trap different combinations of arthropod prey, even when growing at the same locality. On this basis, it has been proposed that co-existing Nepenthes species may be engaged in niche segregation with regards to arthropod prey, avoiding direct competition with congeners by deploying traps that have modifications that enable them to target specific prey types. We examined prey capture among 3 multi-species Nepenthes populations in Borneo, finding that co-existing Nepenthes species do capture different combinations of prey, but that significant interspecific variations in arthropod prey combinations can often be detected only at sub-ordinal taxonomic ranks. In all lowland Nepenthes species examined, the dominant prey taxon is Formicidae, but montane Nepenthes trap few (or no) ants and 2 of the 3 species studied have evolved to target alternative sources of nutrition, such as tree shrew feces. Using similarity and null model analyses, we detected evidence for niche segregation with regards to formicid prey among 5 lowland, sympatric Nepenthes species in Sarawak. However, we were unable to determine whether these results provide support for the niche segregation hypothesis, or whether they simply reflect unquantified variation in heterogeneous habitats and/or ant communities in the study sites. These findings are used to propose improvements to the design of field experiments that seek to test hypotheses about targeted prey capture patterns in Nepenthes.

  1. Prey selectivity affects reproductive success of a corallivorous reef fish.

    Science.gov (United States)

    Brooker, Rohan M; Jones, Geoffrey P; Munday, Philip L

    2013-06-01

    Most animals consume a narrower range of food resources than is potentially available in the environment, but the underlying basis for these preferences is often poorly understood. Foraging theory predicts that prey selection should represent a trade-off between prey preferences based on nutritional value and prey availability. That is, species should consume preferred prey when available, but select less preferred prey when preferred prey is rare. We employed both field observation and laboratory experiments to examine the relationship between prey selection and preferences in the obligate coral-feeding filefish, Oxymonacanthus longirostris. To determine the drivers of prey selection, we experimentally established prey preferences in choice arenas and tested the consequences of prey preferences for key fitness-related parameters. Field studies showed that individuals fed almost exclusively on live corals from the genus Acropora. While diet was dominated by the most abundant species, Acropora nobilis, fish appeared to preferentially select rarer acroporids, such as A. millepora and A. hyacinthus. Prey choice experiments confirmed strong preferences for these corals, suggesting that field consumption is constrained by availability. In a longer-term feeding experiment, reproductive pairs fed on non-preferred corals exhibited dramatic reductions to body weight, and in hepatic and gonad condition, compared with those fed preferred corals. The majority of pairs fed preferred corals spawned frequently, while no spawning was observed for any pairs fed a non-preferred species of coral. These experiments suggest that fish distinguish between available corals based on their intrinsic value as prey, that reproductive success is dependent on the presence of particular coral species, and that differential loss of preferred corals could have serious consequences for the population success of these dietary specialists.

  2. Prey Selection of Scandinavian Wolves: Single Large or Several Small?

    Directory of Open Access Journals (Sweden)

    Håkan Sand

    Full Text Available Research on large predator-prey interactions are often limited to the predators' primary prey, with the potential for prey switching in systems with multiple ungulate species rarely investigated. We evaluated wolf (Canis lupus prey selection at two different spatial scales, i.e., inter- and intra-territorial, using data from 409 ungulate wolf-kills in an expanding wolf population in Scandinavia. This expansion includes a change from a one-prey into a two-prey system with variable densities of one large-sized ungulate; moose (Alces alces and one small-sized ungulate; roe deer (Capreolus capreolus. Among wolf territories, the proportion of roe deer in wolf kills was related to both pack size and roe deer density, but not to moose density. Pairs of wolves killed a higher proportion of roe deer than did packs, and wolves switched to kill more roe deer as their density increased above a 1:1 ratio in relation to the availability of the two species. At the intra-territorial level, wolves again responded to changes in roe deer density in their prey selection whereas we found no effect of snow depth, time during winter, or other predator-related factors on the wolves' choice to kill moose or roe deer. Moose population density was only weakly related to intra-territorial prey selection. Our results show that the functional response of wolves on moose, the species hitherto considered as the main prey, was strongly dependent on the density of a smaller, alternative, ungulate prey. The impact of wolf predation on the prey species community is therefore likely to change with the composition of the multi-prey species community along with the geographical expansion of the wolf population.

  3. Prey Selection of Scandinavian Wolves: Single Large or Several Small?

    Science.gov (United States)

    Eklund, Ann; Zimmermann, Barbara; Wikenros, Camilla; Wabakken, Petter

    2016-01-01

    Research on large predator-prey interactions are often limited to the predators’ primary prey, with the potential for prey switching in systems with multiple ungulate species rarely investigated. We evaluated wolf (Canis lupus) prey selection at two different spatial scales, i.e., inter- and intra-territorial, using data from 409 ungulate wolf-kills in an expanding wolf population in Scandinavia. This expansion includes a change from a one-prey into a two-prey system with variable densities of one large-sized ungulate; moose (Alces alces) and one small-sized ungulate; roe deer (Capreolus capreolus). Among wolf territories, the proportion of roe deer in wolf kills was related to both pack size and roe deer density, but not to moose density. Pairs of wolves killed a higher proportion of roe deer than did packs, and wolves switched to kill more roe deer as their density increased above a 1:1 ratio in relation to the availability of the two species. At the intra-territorial level, wolves again responded to changes in roe deer density in their prey selection whereas we found no effect of snow depth, time during winter, or other predator-related factors on the wolves’ choice to kill moose or roe deer. Moose population density was only weakly related to intra-territorial prey selection. Our results show that the functional response of wolves on moose, the species hitherto considered as the main prey, was strongly dependent on the density of a smaller, alternative, ungulate prey. The impact of wolf predation on the prey species community is therefore likely to change with the composition of the multi-prey species community along with the geographical expansion of the wolf population. PMID:28030549

  4. Prey Selection of Scandinavian Wolves: Single Large or Several Small?

    Science.gov (United States)

    Sand, Håkan; Eklund, Ann; Zimmermann, Barbara; Wikenros, Camilla; Wabakken, Petter

    2016-01-01

    Research on large predator-prey interactions are often limited to the predators' primary prey, with the potential for prey switching in systems with multiple ungulate species rarely investigated. We evaluated wolf (Canis lupus) prey selection at two different spatial scales, i.e., inter- and intra-territorial, using data from 409 ungulate wolf-kills in an expanding wolf population in Scandinavia. This expansion includes a change from a one-prey into a two-prey system with variable densities of one large-sized ungulate; moose (Alces alces) and one small-sized ungulate; roe deer (Capreolus capreolus). Among wolf territories, the proportion of roe deer in wolf kills was related to both pack size and roe deer density, but not to moose density. Pairs of wolves killed a higher proportion of roe deer than did packs, and wolves switched to kill more roe deer as their density increased above a 1:1 ratio in relation to the availability of the two species. At the intra-territorial level, wolves again responded to changes in roe deer density in their prey selection whereas we found no effect of snow depth, time during winter, or other predator-related factors on the wolves' choice to kill moose or roe deer. Moose population density was only weakly related to intra-territorial prey selection. Our results show that the functional response of wolves on moose, the species hitherto considered as the main prey, was strongly dependent on the density of a smaller, alternative, ungulate prey. The impact of wolf predation on the prey species community is therefore likely to change with the composition of the multi-prey species community along with the geographical expansion of the wolf population.

  5. Molecular prey identification in Central European piscivores.

    Science.gov (United States)

    Thalinger, Bettina; Oehm, Johannes; Mayr, Hannes; Obwexer, Armin; Zeisler, Christiane; Traugott, Michael

    2016-01-01

    Diet analysis is an important aspect when investigating the ecology of fish-eating animals and essential for assessing their functional role in food webs across aquatic and terrestrial ecosystems. The identification of fish remains in dietary samples, however, can be time-consuming and unsatisfying using conventional morphological analysis of prey remains. Here, we present a two-step multiplex PCR system, comprised of six assays, allowing for rapid, sensitive and specific detection of fish DNA in dietary samples. This approach encompasses 78 fish and lamprey species native to Central European freshwaters and enables the identification of 31 species, six genera, two families, two orders and two fish family clusters. All targeted taxa were successfully amplified from 25 template molecules, and each assay was specific when tested against a wide range of invertebrates and vertebrates inhabiting aquatic environments. The applicability of the multiplex PCR system was evaluated in a feeding trial, wherein it outperformed morphological prey analysis regarding species-specific prey identification in faeces of Eurasian otters. Additionally, a wide spectrum of fish species was detected in field-collected faecal samples and regurgitated pellets of Common Kingfishers and Great Cormorants, demonstrating the broad applicability of the approach. In conclusion, this multiplex PCR system provides an efficient, easy to use and cost-effective tool for assessing the trophic ecology of piscivores in Central Europe. Furthermore, the multiplex PCRs and the primers described therein will be applicable wherever DNA of the targeted fish species needs to be detected at high sensitivity and specificity. © 2015 The Authors. Molecular Ecology Resources Published by John Wiley & Sons Ltd.

  6. Limit Cycles in Predator-Prey Models

    OpenAIRE

    Puchuri Medina, Liliana

    2017-01-01

    The classic Lotka-Volterra model belongs to a family of differential equations known as “Generalized Lotka-Volterra”, which is part of a classification of four models of quadratic fields with center. These models have been studied to address the Hilbert infinitesimal problem, which consists in determine the number of limit cycles of a perturbed hamiltonian system with center. In this work, we first present an alternative proof of the existence of centers in Lotka-Volterra predator-prey models...

  7. Assassin bug uses aggressive mimicry to lure spider prey.

    Science.gov (United States)

    Wignall, Anne E; Taylor, Phillip W

    2011-05-07

    Assassin bugs (Stenolemus bituberus) hunt web-building spiders by invading the web and plucking the silk to generate vibrations that lure the resident spider into striking range. To test whether vibrations generated by bugs aggressively mimic the vibrations generated by insect prey, we compared the responses of spiders to bugs with how they responded to prey, courting male spiders and leaves falling into the web. We also analysed the associated vibrations. Similar spider orientation and approach behaviours were observed in response to vibrations from bugs and prey, whereas different behaviours were observed in response to vibrations from male spiders and leaves. Peak frequency and duration of vibrations generated by bugs were similar to those generated by prey and courting males. Further, vibrations from bugs had a temporal structure and amplitude that were similar to vibrations generated by leg and body movements of prey and distinctly different to vibrations from courting males or leaves, or prey beating their wings. To be an effective predator, bugs do not need to mimic the full range of prey vibrations. Instead bugs are general mimics of a subset of prey vibrations that fall within the range of vibrations classified by spiders as 'prey'.

  8. Behavior of prey links midwater and demersal piscivorous reef fishes

    Directory of Open Access Journals (Sweden)

    Peter J. Auster

    Full Text Available Pelagic and demersal guilds of piscivorous fishes are linked by a variety of biological and physical processes that mediate interactions with common prey species. Understanding the behaviors of predators and prey can provide insight into the conditions that make such linkages possible. Here we report on the behaviors of mid-water piscivorous fishes and the responses of prey that produce feeding opportunities for demersal piscivorous fishes associated with "live bottom" ledge habitats off the coast of Georgia (northwest Atlantic Ocean. Prey taxa reduced nearest neighbor distances and retreated towards the seafloor during predatory attacks by mid-water fishes. Demersal fishes subsequently attacked and consumed prey in these ephemeral high density patches. No predation by demersal fishes was observed when prey species were at background densities. If the predator-prey interactions of demersal piscivorous fishes are commonly mediated by the predatory behavior of midwater piscivorous fishes and their prey, such indirect facilitative behaviors may be important in terms of the population processes (e.g., prey consumption and growth rates of these demersal fishes.

  9. Rapid prey evolution can alter the structure of predator-prey communities

    NARCIS (Netherlands)

    Friman, V. -P.; Jousset, A.; Buckling, A.

    Although microevolution has been shown to play an important role in pairwise antagonistic species interactions, its importance in more complex communities has received little attention. Here, we used two Pseudomonas fluorescens prey bacterial strains (SBW25 and F113) and Tetrahymena thermophila

  10. Coexistence for an Almost Periodic Predator-Prey Model with Intermittent Predation Driven by Discontinuous Prey Dispersal

    Directory of Open Access Journals (Sweden)

    Yantao Luo

    2017-01-01

    Full Text Available An almost periodic predator-prey model with intermittent predation and prey discontinuous dispersal is studied in this paper, which differs from the classical continuous and impulsive dispersal predator-prey models. The intermittent predation behavior of the predator species only happens in the channels between two patches where the discontinuous migration movement of the prey species occurs. Using analytic approaches and comparison theorems of the impulsive differential equations, sufficient criteria on the boundedness, permanence, and coexistence for this system are established. Finally, numerical simulations demonstrate that, for an intermittent predator-prey model, both the intermittent predation and intrinsic growth rates of the prey and predator species can greatly impact the permanence, extinction, and coexistence of the population.

  11. Echolocating bats use a nearly time-optimal strategy to intercept prey.

    Directory of Open Access Journals (Sweden)

    Kaushik Ghose

    2006-05-01

    Full Text Available Acquisition of food in many animal species depends on the pursuit and capture of moving prey. Among modern humans, the pursuit and interception of moving targets plays a central role in a variety of sports, such as tennis, football, Frisbee, and baseball. Studies of target pursuit in animals, ranging from dragonflies to fish and dogs to humans, have suggested that they all use a constant bearing (CB strategy to pursue prey or other moving targets. CB is best known as the interception strategy employed by baseball outfielders to catch ballistic fly balls. CB is a time-optimal solution to catch targets moving along a straight line, or in a predictable fashion--such as a ballistic baseball, or a piece of food sinking in water. Many animals, however, have to capture prey that may make evasive and unpredictable maneuvers. Is CB an optimum solution to pursuing erratically moving targets? Do animals faced with such erratic prey also use CB? In this paper, we address these questions by studying prey capture in an insectivorous echolocating bat. Echolocating bats rely on sonar to pursue and capture flying insects. The bat's prey may emerge from foliage for a brief time, fly in erratic three-dimensional paths before returning to cover. Bats typically take less than one second to detect, localize and capture such insects. We used high speed stereo infra-red videography to study the three dimensional flight paths of the big brown bat, Eptesicus fuscus, as it chased erratically moving insects in a dark laboratory flight room. We quantified the bat's complex pursuit trajectories using a simple delay differential equation. Our analysis of the pursuit trajectories suggests that bats use a constant absolute target direction strategy during pursuit. We show mathematically that, unlike CB, this approach minimizes the time it takes for a pursuer to intercept an unpredictably moving target. Interestingly, the bat's behavior is similar to the interception strategy

  12. Echolocating bats use a nearly time-optimal strategy to intercept prey.

    Science.gov (United States)

    Ghose, Kaushik; Horiuchi, Timothy K; Krishnaprasad, P S; Moss, Cynthia F

    2006-05-01

    Acquisition of food in many animal species depends on the pursuit and capture of moving prey. Among modern humans, the pursuit and interception of moving targets plays a central role in a variety of sports, such as tennis, football, Frisbee, and baseball. Studies of target pursuit in animals, ranging from dragonflies to fish and dogs to humans, have suggested that they all use a constant bearing (CB) strategy to pursue prey or other moving targets. CB is best known as the interception strategy employed by baseball outfielders to catch ballistic fly balls. CB is a time-optimal solution to catch targets moving along a straight line, or in a predictable fashion--such as a ballistic baseball, or a piece of food sinking in water. Many animals, however, have to capture prey that may make evasive and unpredictable maneuvers. Is CB an optimum solution to pursuing erratically moving targets? Do animals faced with such erratic prey also use CB? In this paper, we address these questions by studying prey capture in an insectivorous echolocating bat. Echolocating bats rely on sonar to pursue and capture flying insects. The bat's prey may emerge from foliage for a brief time, fly in erratic three-dimensional paths before returning to cover. Bats typically take less than one second to detect, localize and capture such insects. We used high speed stereo infra-red videography to study the three dimensional flight paths of the big brown bat, Eptesicus fuscus, as it chased erratically moving insects in a dark laboratory flight room. We quantified the bat's complex pursuit trajectories using a simple delay differential equation. Our analysis of the pursuit trajectories suggests that bats use a constant absolute target direction strategy during pursuit. We show mathematically that, unlike CB, this approach minimizes the time it takes for a pursuer to intercept an unpredictably moving target. Interestingly, the bat's behavior is similar to the interception strategy implemented in some

  13. The Coevolution of "Tyrannosaurus" & Its Prey: Could "Tyrannosaurus" Chase down & Kill a "Triceratops" for Lunch?

    Science.gov (United States)

    May, S. Randolph

    2014-01-01

    Students will analyze the coevolution of the predator-prey relationships between "Tyrannosaurus rex" and its prey species using analyses of animal speeds from fossilized trackways, prey-animal armaments, adaptive behaviors, bite marks on prey-animal fossils, predator-prey ratios, and scavenger competition. The students will be asked to…

  14. Diet choice of a predator in the wild: overabundance of prey and missed opportunities along the prey capture sequence

    OpenAIRE

    Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

    2012-01-01

    Optimal diet theory (ODT) postulates that predators adjust their foraging decisions by calculating a prey value from the potential biomass gain, handling time, prey vulnerability and encounter rate. Tests of ODT have however so far mainly been restricted to laboratory settings. By video surveillance, we gathered a large data set of more than 2000 field observations of crab spider (Misumena vatia) encounters with potential prey. We then tested whether the complex ODT or two simpler models (pre...

  15. Impact of communicative head movements on the quality of functional near-infrared spectroscopy signals: negligible effects for affirmative and negative gestures and consistent artifacts related to raising eyebrows

    Science.gov (United States)

    Balardin, Joana Bisol; Morais, Guilherme Augusto Zimeo; Furucho, Rogério Akira; Trambaiolli, Lucas Romualdo; Sato, João Ricardo

    2017-04-01

    Functional near-infrared spectroscopy (fNIRS) is currently one of the most promising tools in the neuroscientific research to study brain hemodynamics during naturalistic social communication. The application of fNIRS by studies in this field of knowledge has been widely justified by its strong resilience to motion artifacts, including those that might be generated by communicative head and facial movements. Previous studies have focused on the identification and correction of these artifacts, but a quantification of the differential contribution of common communicative movements on the quality of fNIRS signals is still missing. We assessed the impact of four movements (nodding head up and down, reading aloud, nodding head sideways, and raising eyebrows) performed during rest and task conditions on two metrics of signal quality control: an estimative of signal-to-noise performance and the negative correlation between oxygenated and deoxygenated hemoglobin (oxy-Hb and deoxy-Hb). Channel-wise group analysis confirmed the robustness of the fNIRS technique to head nodding movements but showed a large effect of raising eyebrows in both signal quality control metrics, both during task and rest conditions. Reading aloud did not disrupt the expected anticorrelation between oxy-Hb and deoxy-Hb but had a relatively large effect on signal-to-noise performance. These findings may have implications to the interpretation of fNIRS studies examining communicative processes.

  16. Impact of communicative head movements on the quality of functional near-infrared spectroscopy signals: negligible effects for affirmative and negative gestures and consistent artifacts related to raising eyebrows.

    Science.gov (United States)

    Balardin, Joana Bisol; Zimeo Morais, Guilherme Augusto; Furucho, Rogério Akira; Trambaiolli, Lucas Romualdo; Sato, João Ricardo

    2017-04-01

    Functional near-infrared spectroscopy (fNIRS) is currently one of the most promising tools in the neuroscientific research to study brain hemodynamics during naturalistic social communication. The application of fNIRS by studies in this field of knowledge has been widely justified by its strong resilience to motion artifacts, including those that might be generated by communicative head and facial movements. Previous studies have focused on the identification and correction of these artifacts, but a quantification of the differential contribution of common communicative movements on the quality of fNIRS signals is still missing. We assessed the impact of four movements (nodding head up and down, reading aloud, nodding head sideways, and raising eyebrows) performed during rest and task conditions on two metrics of signal quality control: an estimative of signal-to-noise performance and the negative correlation between oxygenated and deoxygenated hemoglobin (oxy-Hb and deoxy-Hb). Channel-wise group analysis confirmed the robustness of the fNIRS technique to head nodding movements but showed a large effect of raising eyebrows in both signal quality control metrics, both during task and rest conditions. Reading aloud did not disrupt the expected anticorrelation between oxy-Hb and deoxy-Hb but had a relatively large effect on signal-to-noise performance. These findings may have implications to the interpretation of fNIRS studies examining communicative processes.

  17. Evaluating prey switching in wolf-ungulate systems.

    Science.gov (United States)

    Garrott, Robert A; Bruggeman, Jason E; Becker, Matthew S; Kalinowski, Steven T; White, P J

    2007-09-01

    Wolf restoration has become a widely accepted conservation and management practice throughout North America and Europe, though the ecosystem effects of returning top carnivores remain both scientific and societal controversies. Mathematical models predicting and describing wolf-ungulate interactions are typically limited to the wolves' primary prey, with the potential for prey switching in wolf-multiple-ungulate systems only suggested or assumed by a number of investigators. We used insights gained from experiments on small taxa and field data from ongoing wolf-ungulate studies to construct a model of predator diet composition for a wolf-elk-bison system in Yellowstone National Park, Wyoming, USA. The model explicitly incorporates differential vulnerability of the ungulate prey types to predation, predator preference, differences in prey biomass, and the possibility of prey switching. Our model demonstrates wolf diet shifts with changes in relative abundance of the two prey, with the dynamics of this shift dependent on the combined influences of preference, differential vulnerability, relative abundances of prey, and whether or not switching occurs. Differences in vulnerability between elk and bison, and strong wolf preference for elk, result in an abrupt dietary shift occurring only when elk are very rare relative to bison, whereas incorporating switching initiates the dietary shift more gradually and at higher bison-elk ratios. We demonstrate how researchers can apply these equations in newly restored wolf-two-prey systems to empirically evaluate whether prey switching is occurring. Each coefficient in the model has a biological interpretation, and most can be directly estimated from empirical data collected from field studies. Given the potential for switching to dramatically influence predator-prey dynamics and the wide range of expected prey types and abundances in some systems where wolves are present and/or being restored, we suggest that this is an

  18. Infrared astronomy

    International Nuclear Information System (INIS)

    Setti, G.; Fazio, G.

    1978-01-01

    This volume contains lectures describing the important achievements in infrared astronomy. The topics included are galactic infrared sources and their role in star formation, the nature of the interstellar medium and galactic structure, the interpretation of infrared, optical and radio observations of extra-galactic sources and their role in the origin and structure of the universe, instrumental techniques and a review of future space observations. (C.F.)

  19. Feeding State Modulates Behavioral Choice and Processing of Prey Stimuli in the Zebrafish Tectum.

    Science.gov (United States)

    Filosa, Alessandro; Barker, Alison J; Dal Maschio, Marco; Baier, Herwig

    2016-05-04

    Animals use the sense of vision to scan their environment, respond to threats, and locate food sources. The neural computations underlying the selection of a particular behavior, such as escape or approach, require flexibility to balance potential costs and benefits for survival. For example, avoiding novel visual objects reduces predation risk but negatively affects foraging success. Zebrafish larvae approach small, moving objects ("prey") and avoid large, looming objects ("predators"). We found that this binary classification of objects by size is strongly influenced by feeding state. Hunger shifts behavioral decisions from avoidance to approach and recruits additional prey-responsive neurons in the tectum, the main visual processing center. Both behavior and tectal function are modulated by signals from the hypothalamic-pituitary-interrenal axis and the serotonergic system. Our study has revealed a neuroendocrine mechanism that modulates the perception of food and the willingness to take risks in foraging decisions. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Red fox prey demands and implications to prairie duck production

    Science.gov (United States)

    Sargeant, A.B.

    1978-01-01

    Experiments were conducted during spring and summer with 33 red foxes (Vulpes vulpes) to determine prey demands, feeding characteristics, and growth rates using natural foods. Pups began eating prey the 4th week after birth. Then, prey consumption averaged 1.38 and 1.90 kg/pup/week for weeks 5-8 and 9-12 of the denning season respectively, and 2.54 kg/pup/week for the postdenning period. Feeding by adults averaged 2.25 kg/adult/week. Free water was not needed by either pups or adults. About 90 percent of the prey offered to pups on simulated natural diets was consumed, remains varied with prey availability and prey type. Prey biomass required by a typical fox family was estimated at 18.5 kg/km2 for the 12-week denning season and 2.4 kg/km2/week for the postdenning period. Because of the large prey demands, ducks could represent a small part of the foxes' diet and yet be of consequence to the productivity of particular species. An example is provided for the mallard (Anas platyrhynchos).

  1. Determination of carnivores prey base by scat analysis in Samburu ...

    African Journals Online (AJOL)

    Administrator

    This study determined the prey base for four main carnivores found in Samburu community group ranches and ... a result of the hydrolysis of protein that acts as cement for the keratin ... prey component between predator species that may be attributed to ... causing ever-closer interaction between humans and wildlife. This is ...

  2. Stationary Patterns in One-Predator Two-Prey Models

    DEFF Research Database (Denmark)

    Pedersen, Michael; Zhigui, Lin

    1999-01-01

    Weakly-coupled elliptic system decribing models of simple three-species food webs such as the one-predator, two-prey modelis discussed. We show thatthere is no non-constant solution if diffusions or inter-specific competitions are strong, or if the intrinsic growths of the prey are slow...

  3. Stationary Patterns in One-Predator Two-Prey Models

    DEFF Research Database (Denmark)

    Pedersen, Michael; Zhigui, Lin

    1999-01-01

    Weakly-coupled elliptic system decribing models of simple three-species food webs such as the one-predator, two-prey model is discussed. We show that there is no non-constant solution if diffusions or inter-specific competitions are strong, or if the intrinsic growths of the prey are slow...

  4. Production of live prey for marine fish larvae

    OpenAIRE

    Kraul, S

    1989-01-01

    Tropical marine fish larvae vary in their requirements for live planktonic food. Selection of live prey species for culture depends on larval size and larval tolerance of water quality. This report describes some of the cultured prey species, and their uses and limits as effective food for fish larvae. Methods are presented for the culture of phytoplankton, rotifers, copepods, and other live feeds.

  5. Behavioral response races, predator-prey shell games, ecology of fear, and patch use of pumas and their ungulate prey.

    Science.gov (United States)

    Laundré, John W

    2010-10-01

    The predator-prey shell game predicts random movement of prey across the landscape, whereas the behavioral response race and landscape of fear models predict that there should be a negative relationship between the spatial distribution of a predator and its behaviorally active prey. Additionally, prey have imperfect information on the whereabouts of their predator, which the predator should incorporate in its patch use strategy. I used a one-predator-one-prey system, puma (Puma concolor)-mule deer (Odocoileus hemionus) to test the following predictions regarding predator-prey distribution and patch use by the predator. (1) Pumas will spend more time in high prey risk/low prey use habitat types, while deer will spend their time in low-risk habitats. Pumas should (2) select large forage patches more often, (3) remain in large patches longer, and (4) revisit individual large patches more often than individual smaller ones. I tested these predictions with an extensive telemetry data set collected over 16 years in a study area of patchy forested habitat. When active, pumas spent significantly less time in open areas of low intrinsic predation risk than did deer. Pumas used large patches more than expected, revisited individual large patches significantly more often than smaller ones, and stayed significantly longer in larger patches than in smaller ones. The results supported the prediction of a negative relationship in the spatial distribution of a predator and its prey and indicated that the predator is incorporating the prey's imperfect information about its presence. These results indicate a behavioral complexity on the landscape scale that can have far-reaching impacts on predator-prey interactions.

  6. Feeding, prey selection and prey encounter mechanisms in the heterotrophic dinoflagellate Noctiluca scintillans

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Titelman, J.

    1998-01-01

    /or that microscale shear brings it into contact with prey. Noctiluca scintillans has a specific carbon content 1-2 orders of magnitude less than that typical for protists and, thus, an inflated volume. It also has a density slightly less than that of the ambient water and therefore ascends at high velocities...... (similar to 1 m h(- 1)). In stagnant water, clearance rates of latex spheres (5-80 mu m) increased approximately with prey particle size squared. This scaling is consistent with N.scintillans being an interception feeder. However, absolute clearance rates were substantially lower than those predicted...... higher rates than latex beads and other phytoplankters, particularly dinoflagellates. We propose that diatoms stick more efficiently than latex beads to the mucus of N.scintillans and that dinoflagellates reduce fatal contact behaviorally. We conclude that N.scintillans is an interception feeder...

  7. Functional responses of human hunters to their prey - why harvest statistics may not always reflect changes in prey population abundance

    DEFF Research Database (Denmark)

    Kahlert, Johnny Abildgaard; Fox, Anthony David; Heldbjerg, Henning

    pigeon Columba palumbus, coot Fulica atra, grey partridge Perdix perdix, roe deer Capreolus capreolus and brown hare Lepus europaeus in Denmark. If we consider hunting a form of predator-prey interaction, the annual kill can be viewed as a predator functional response to prey population size. Convergence...

  8. Harvesting policy for a delayed stage-structured Holling II predator-prey model with impulsive stocking prey

    International Nuclear Information System (INIS)

    Jiao Jianjun; Meng Xinzhu; Chen Lansun

    2009-01-01

    A predator-prey model with a stage structure for the predator, which improves the assumption that each individual predator has the same ability to capture prey, is proposed by Wang et al. [Wang W, Mulone G, Salemi F, Salone V. Permanence and stability of a stage-structured predator-prey model. J Math Anal Appl 2001;262:499-528]. It is assumed that immature individuals and mature individuals of the predator are divided by a fixed age and that immature predators do not have the ability to attack prey. We do economic management behavior for Wang model [Wang et al., 2001] by continuous harvesting on predator and impulsive stocking on prey. Then, a delayed stage-structured Holling type II predator-prey model with impulsive stocking prey and continuous harvesting predator is established. It is also assumed that the predating products of the predator is only to increase its bearing ability. We obtain the sufficient conditions of the global attractivity of predator-extinction boundary periodic solution and the permanence of the system. Our results show that the behavior of impulsive stocking prey plays an important role for the permanence of the system, and provide tactical basis for the biological resource management. Further, the numerical analysis is also inserted to illuminate the dynamics of the system.

  9. Prey risk allocation in a grazing ecosystem.

    Science.gov (United States)

    Gude, Justin A; Garrott, Robert A; Borkowski, John J; King, Fred

    2006-02-01

    Understanding the behaviorally mediated indirect effects of predators in ecosystems requires knowledge of predator-prey behavioral interactions. In predator-ungulate-plant systems, empirical research quantifying how predators affect ungulate group sizes and distribution, in the context of other influential variables, is particularly needed. The risk allocation hypothesis proposes that prey behavioral responses to predation risk depend on background frequencies of exposure to risk, and it can be used to make predictions about predator-ungulate-plant interactions. We determined non-predation variables that affect elk (Cervus elaphus) group sizes and distribution on a winter range in the Greater Yellowstone Ecosystem (GYE) using logistic and log-linear regression on surveys of 513 1-km2 areas conducted over two years. Employing model selection techniques, we evaluated risk allocation and other a priori hypotheses of elk group size and distributional responses to wolf (Canis lupus) predation risk while accounting for influential non-wolf-predation variables. We found little evidence that wolves affect elk group sizes, which were strongly influenced by habitat type and hunting by humans. Following predictions from the risk allocation hypothesis, wolves likely created a more dynamic elk distribution in areas that they frequently hunted, as elk tended to move following wolf encounters in those areas. This response should dilute elk foraging pressure on plant communities in areas where they are frequently hunted by wolves. We predict that this should decrease the spatial heterogeneity of elk impacts on grasslands in areas that wolves frequently hunt. We also predict that this should decrease browsing pressure on heavily browsed woody plant stands in certain areas, which is supported by recent research in the GYE.

  10. Competing conservation objectives for predators and prey: estimating killer whale prey requirements for Chinook salmon.

    Directory of Open Access Journals (Sweden)

    Rob Williams

    Full Text Available Ecosystem-based management (EBM of marine resources attempts to conserve interacting species. In contrast to single-species fisheries management, EBM aims to identify and resolve conflicting objectives for different species. Such a conflict may be emerging in the northeastern Pacific for southern resident killer whales (Orcinus orca and their primary prey, Chinook salmon (Oncorhynchus tshawytscha. Both species have at-risk conservation status and transboundary (Canada-US ranges. We modeled individual killer whale prey requirements from feeding and growth records of captive killer whales and morphometric data from historic live-capture fishery and whaling records worldwide. The models, combined with caloric value of salmon, and demographic and diet data for wild killer whales, allow us to predict salmon quantities needed to maintain and recover this killer whale population, which numbered 87 individuals in 2009. Our analyses provide new information on cost of lactation and new parameter estimates for other killer whale populations globally. Prey requirements of southern resident killer whales are difficult to reconcile with fisheries and conservation objectives for Chinook salmon, because the number of fish required is large relative to annual returns and fishery catches. For instance, a U.S. recovery goal (2.3% annual population growth of killer whales over 28 years implies a 75% increase in energetic requirements. Reducing salmon fisheries may serve as a temporary mitigation measure to allow time for management actions to improve salmon productivity to take effect. As ecosystem-based fishery management becomes more prevalent, trade-offs between conservation objectives for predators and prey will become increasingly necessary. Our approach offers scenarios to compare relative influence of various sources of uncertainty on the resulting consumption estimates to prioritise future research efforts, and a general approach for assessing the extent of

  11. Acoustic shadows help gleaning bats find prey, but may be defeated by prey acoustic camouflage on rough surfaces.

    Science.gov (United States)

    Clare, Elizabeth L; Holderied, Marc W

    2015-09-01

    Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an 'acoustic shadow' cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for 'acoustic camouflage' as an anti-predator defence mechanism.

  12. Colour polymorphic lures exploit innate preferences for spectral versus luminance cues in dipteran prey.

    Science.gov (United States)

    White, Thomas E; Kemp, Darrell J

    2017-08-14

    Theory predicts that colour polymorphism may be favored by variation in the visual context under which signals are perceived. The context encompasses all environmental determinants of light availability and propagation, but also the dynamics of perception in receivers. Color vision involves the neural separation of information into spectral versus luminance channels, which often differentially guide specific tasks. Here we explicitly tested whether this discrete perceptual basis contributes to the maintenance of polymorphism in a prey-luring system. The orb-weaving spider Gasteracantha fornicata is known to attract a broad community of primarily dipteran prey due to their conspicuous banded dorsal signal. They occur in two morphs ("white" and "yellow") which should, respectively, generate greater luminance and color contrast in the dipteran eye. Given that arthropods often rely upon luminance-versus-spectral cues for relatively small-versus-large stimulus detection, we predicted a switch in relative attractiveness among morphs according to apparent spider size. Our experimental tests used colour-naïve individuals of two known prey species (Drosophila hydei and Musca domestica) in replicate Y-maze choice trials designed to manipulate the apparent size of spider models via the distance at which they are viewed. Initial trials confirmed that flies were attracted to each G. fornicata morph in single presentations. When given a simultaneous choice between morphs against a viewing background typical of those encountered in nature, flies exhibited no preference regardless of the visual angle subtended by models. However, when backgrounds were adjusted to nearer the extremes of those of each morph in the wild, flies were more attracted by white morphs when presented at longer range (consistent with a reliance on achromatic cues), yet were unbiased in their close-range choice. While not fully consistent with predictions (given the absence of a differential preference for

  13. The effect of structural complexity, prey density, and "predator-free space" on prey survivorship at created oyster reef mesocosms

    Science.gov (United States)

    Humphries, Austin T.; La Peyre, Megan K.; Decossas, Gary A.

    2011-01-01

    Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and “predator-free space” to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of “predator-free space” was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require “predator-free space” measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of “predator-free space” are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats.

  14. A snail-eating snake recognizes prey handedness.

    Science.gov (United States)

    Danaisawadi, Patchara; Asami, Takahiro; Ota, Hidetoshi; Sutcharit, Chirasak; Panha, Somsak

    2016-04-05

    Specialized predator-prey interactions can be a driving force for their coevolution. Southeast Asian snail-eating snakes (Pareas) have more teeth on the right mandible and specialize in predation on the clockwise-coiled (dextral) majority in shelled snails by soft-body extraction. Snails have countered the snakes' dextral-predation by recurrent coil reversal, which generates diverse counterclockwise-coiled (sinistral) prey where Pareas snakes live. However, whether the snake predator in turn evolves any response to prey reversal is unknown. We show that Pareas carinatus living with abundant sinistrals avoids approaching or striking at a sinistral that is more difficult and costly to handle than a dextral. Whenever it strikes, however, the snake succeeds in predation by handling dextral and sinistral prey in reverse. In contrast, P. iwasakii with little access to sinistrals on small peripheral islands attempts and frequently misses capturing a given sinistral. Prey-handedness recognition should be advantageous for right-handed snail-eating snakes where frequently encountering sinistrals. Under dextral-predation by Pareas snakes, adaptive fixation of a prey population for a reversal gene instantaneously generates a sinistral species because interchiral mating is rarely possible. The novel warning, instead of sheltering, effect of sinistrality benefitting both predators and prey could further accelerate single-gene ecological speciation by left-right reversal.

  15. Tactile Experience Shapes Prey-Capture Behavior in Etruscan Shrews

    Directory of Open Access Journals (Sweden)

    Michael eBrecht

    2012-06-01

    Full Text Available A crucial role of tactile experience for the maturation of neural response properties in the somatosensory system is well established, but little is known about the role of tactile experience in the development of tactile behaviors. Here we study how tactile experience affects prey capture behavior in Etruscan shrews, Suncus etruscus. Prey capture in adult shrews is a high-speed behavior that relies on precise attacks guided by tactile Gestalt cues. We studied the role of tactile experience by three different approaches. First, we analyzed the hunting skills of young shrews right after weaning. We found that prey capture in young animals is most but not all aspects similar to that of adults. Second we performed whisker trimming for three to four weeks after birth. Such deprivation resulted in a lasting disruption of prey capture even after whisker re-growth: attacks lacked precise targeting and had a lower success rate. Third, we presented adult shrews with an entirely novel prey species, the giant cockroach. The shape of this roach is very different from the shrew’s normal (cricket prey and the thorax – the preferred point of attack in crickets – is protected a heavy cuticle. Initially shrews attacked giant roaches the same way they attack crickets and targeted the thoracic region. With progressive experience, however, shrews adopted a new attack strategy targeting legs and underside of the roaches while avoiding other body parts. Speed and efficiency of attacks improved. These data suggest that tactile experience shapes prey capture behavior.

  16. Predicting prey population dynamics from kill rate, predation rate and predator-prey ratios in three wolf-ungulate systems.

    Science.gov (United States)

    Vucetich, John A; Hebblewhite, Mark; Smith, Douglas W; Peterson, Rolf O

    2011-11-01

    1. Predation rate (PR) and kill rate are both fundamental statistics for understanding predation. However, relatively little is known about how these statistics relate to one another and how they relate to prey population dynamics. We assess these relationships across three systems where wolf-prey dynamics have been observed for 41 years (Isle Royale), 19 years (Banff) and 12 years (Yellowstone). 2. To provide context for this empirical assessment, we developed theoretical predictions of the relationship between kill rate and PR under a broad range of predator-prey models including predator-dependent, ratio-dependent and Lotka-Volterra dynamics. 3. The theoretical predictions indicate that kill rate can be related to PR in a variety of diverse ways (e.g. positive, negative, unrelated) that depend on the nature of predator-prey dynamics (e.g. structure of the functional response). These simulations also suggested that the ratio of predator-to-prey is a good predictor of prey growth rate. That result motivated us to assess the empirical relationship between the ratio and prey growth rate for each of the three study sites. 4. The empirical relationships indicate that PR is not well predicted by kill rate, but is better predicted by the ratio of predator-to-prey. Kill rate is also a poor predictor of prey growth rate. However, PR and ratio of predator-to-prey each explained significant portions of variation in prey growth rate for two of the three study sites. 5. Our analyses offer two general insights. First, Isle Royale, Banff and Yellowstone are similar insomuch as they all include wolves preying on large ungulates. However, they also differ in species diversity of predator and prey communities, exploitation by humans and the role of dispersal. Even with the benefit of our analysis, it remains difficult to judge whether to be more impressed by the similarities or differences. This difficulty nicely illustrates a fundamental property of ecological

  17. Parental and embryonic experiences with predation risk affect prey offspring behaviour and performance.

    Science.gov (United States)

    Donelan, Sarah C; Trussell, Geoffrey C

    2018-03-14

    Because phenotypic plasticity can operate both within and between generations, phenotypic outcomes are often shaped by a complex history of environmental signals. For example, parental and embryonic experiences with predation risk can both independently and interactively influence prey offspring traits early in their life. Parental and embryonic risk experiences can also independently shape offspring phenotypes throughout an offspring's ontogeny, but the persistence of their interactive effects throughout offspring ontogeny is unknown. We examined the effects of parental and embryonic experiences with predation risk on the response of 1-year-old prey (the carnivorous snail, Nucella lapillus ) offspring to current predation risk. We found that parental and embryonic risk experiences had largely independent effects on offspring performance and that these effects were context dependent. Parental experience with risk had strong impacts on multiple offspring traits in the presence of current risk that generally improved offspring performance under risk, but embryonic risk experience had relatively weaker effects and only operated in the absence of current risk to reduce offspring growth. These results illustrate that past environmental experiences can dynamically shape organism phenotypes across ontogeny and that attention to these effects is key to a better understanding of predator/prey dynamics in natural systems. © 2018 The Author(s).

  18. Individual prey choices of octopuses: Are they generalist or specialist?

    Directory of Open Access Journals (Sweden)

    Jennifer A. MATHER, Tatiana S. LEITE, Allan T. BATISTA

    2012-08-01

    Full Text Available Prey choice is often evaluated at the species or population level. Here, we analyzed the diet of octopuses of different populations with the aim to assess the importance of individual feeding habits as a factor affecting prey choice. Two methods were used, an assessment of the extent to which an individual octopus made choices of species representative of those population (PSi and IS and 25% cutoff values for number of choices and percentage intake of individual on their prey. In one population of Octopus cf vulgaris in Bermuda individuals were generalist by IS=0.77, but most chose many prey of the same species, and were specialists on it by >75% intake. Another population had a wider prey selection, still generalist with PSi=0.66, but two individuals specialized by choices. In Bonaire, there was a wide range of prey species chosen, and the population was specialists by IS= 0.42. Individual choices revealed seven specialists and four generalists. A population of Octopus cyanea in Hawaii all had similar choices of crustaceans, so the population was generalist by IS with 0.74. But by individual choices, three were considered a specialist. A population of Enteroctopus dofleini from Puget Sound had a wide range of preferences, in which seven were also specialists, IS=0.53. By individual choices, thirteen were also specialists. Given the octopus specialty of learning during foraging, we hypothesize that both localized prey availability and individual personality differences could influence the exploration for prey and this translates into different prey choices across individuals and populations showed in this study [Current Zoology 58 (4: 597-603, 2012].

  19. Predator cannibalism can intensify negative impacts on heterospecific prey.

    Science.gov (United States)

    Takatsu, Kunio; Kishida, Osamu

    2015-07-01

    Although natural populations consist of individuals with different traits, and the degree of phenotypic variation varies among populations, the impact of phenotypic variation on ecological interactions has received little attention, because traditional approaches to community ecology assume homogeneity of individuals within a population. Stage structure, which is a common way of generating size and developmental variation within predator populations, can drive cannibalistic interactions, which can affect the strength of predatory effects on the predator's heterospecific prey. Studies have shown that predator cannibalism weakens predatory effects on heterospecific prey by reducing the size of the predator population and by inducing less feeding activity of noncannibal predators. We predict, however, that predator cannibalism, by promoting rapid growth of the cannibals, can also intensify predation pressure on heterospecific prey, because large predators have large resource requirements and may utilize a wider variety of prey species. To test this hypothesis, we conducted an experiment in which we created carnivorous salamander (Hynobius retardatus) populations with different stage structures by manipulating the salamander's hatch timing (i.e., populations with large or small variation in the timing of hatching), and explored the resultant impacts on the abundance, behavior, morphology, and life history of the salamander's large heterospecific prey, Rana pirica frog tadpoles. Cannibalism was rare in salamander populations having small hatch-timing variation, but was frequent in those having large hatch-timing variation. Thus, giant salamander cannibals occurred only in the latter. We clearly showed that salamander giants exerted strong predation pressure on frog tadpoles, which induced large behavioral and morphological defenses in the tadpoles and caused them to metamorphose late at large size. Hence, predator cannibalism arising from large variation in the timing

  20. Temperature and prey capture: opposite relationships in two predator taxa

    DEFF Research Database (Denmark)

    Kruse, Peter Dalgas; Toft, Søren; Sunderland, Keith

    2008-01-01

    to catch swiftly moving prey. 2. The first experiment examined the spontaneous locomotor activity of the predators and of fruit flies at different temperatures (5, 10, 15, 20, 25, and 30 °C) and light conditions (light, dark). A second experiment examined the effect of temperature and light...... different prey groups within the set of potential prey at different times of the day or at different seasons. The ability of many carabid beetles to forage at low temperatures may have nutritional benefits and increases the diversity of interactions in terrestrial food webs....

  1. A self-organized system of smart preys and predators

    Energy Technology Data Exchange (ETDEWEB)

    Rozenfeld, Alejandro F. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP, CONICET, Suc. 4, C.C. 16 (1900) La Plata (Argentina); Albano, Ezequiel V. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP, CONICET, Suc. 4, C.C. 16 (1900) La Plata (Argentina)]. E-mail: ealbano@inifta.unlp.edu.ar

    2004-11-22

    Based on the fact that, a standard prey-predator model (SPPM), exhibits irreversible phase transitions, belonging to the universality class of directed percolation (DP), between prey-predator coexistence and predator extinction [Phys. Lett. A 280 (2001) 45], a self-organized prey-predator model (SOPPM) is formulated and studied by means of extensive Monte Carlo simulations. The SOPPM is achieved defining the parameters of the SPPM as functions of the density of species. It is shown that the SOPPM self-organizes into an active state close the absorbing phase of the SPPM, and consequently their avalanche exponents also belong to the universality class of DP.

  2. Modelling prey consumption and switching by UK grey seals

    DEFF Research Database (Denmark)

    Smout, Sophie; Rindorf, Anna; Hammond, Philip S.

    2014-01-01

    Grey seals (Halichoerus grypus) are adaptable generalist predatorswhose diet includes commercial fish species such as cod. Consumption by the seals may reduce the size of some fish stocks or have an adverse effect on stock recovery programmes, especially because predation may trap sparse prey...... populations in a “predator pit”. To assess the likely impact of such effects, it is important to know how consumption and consequent predation mortality respond to the changing availability of prey.Wepresent a model of grey seal consumption as a function of the availability of multiple prey types [a Multi...

  3. Dominant glint based prey localization in horseshoe bats: a possible strategy for noise rejection.

    Science.gov (United States)

    Vanderelst, Dieter; Reijniers, Jonas; Firzlaff, Uwe; Peremans, Herbert

    2011-12-01

    Rhinolophidae or Horseshoe bats emit long and narrowband calls. Fluttering insect prey generates echoes in which amplitude and frequency shifts are present, i.e. glints. These glints are reliable cues about the presence of prey and also encode certain properties of the prey. In this paper, we propose that these glints, i.e. the dominant glints, are also reliable signals upon which to base prey localization. In contrast to the spectral cues used by many other bats, the localization cues in Rhinolophidae are most likely provided by self-induced amplitude modulations generated by pinnae movement. Amplitude variations in the echo not introduced by the moving pinnae can be considered as noise interfering with the localization process. The amplitude of the dominant glints is very stable. Therefore, these parts of the echoes contain very little noise. However, using only the dominant glints potentially comes at a cost. Depending on the flutter rate of the insect, a limited number of dominant glints will be present in each echo giving the bat a limited number of sample points on which to base localization. We evaluate the feasibility of a strategy under which Rhinolophidae use only dominant glints. We use a computational model of the echolocation task faced by Rhinolophidae. Our model includes the spatial filtering of the echoes by the morphology of the sonar apparatus of Rhinolophus rouxii as well as the amplitude modulations introduced by pinnae movements. Using this model, we evaluate whether the dominant glints provide Rhinolophidae with enough information to perform localization. Our simulations show that Rhinolophidae can use dominant glints in the echoes as carriers for self-induced amplitude modulations serving as localization cues. In particular, it is shown that the reduction in noise achieved by using only the dominant glints outweighs the information loss that occurs by sampling the echo. © 2011 Vanderelst et al.

  4. Dominant glint based prey localization in horseshoe bats: a possible strategy for noise rejection.

    Directory of Open Access Journals (Sweden)

    Dieter Vanderelst

    2011-12-01

    Full Text Available Rhinolophidae or Horseshoe bats emit long and narrowband calls. Fluttering insect prey generates echoes in which amplitude and frequency shifts are present, i.e. glints. These glints are reliable cues about the presence of prey and also encode certain properties of the prey. In this paper, we propose that these glints, i.e. the dominant glints, are also reliable signals upon which to base prey localization. In contrast to the spectral cues used by many other bats, the localization cues in Rhinolophidae are most likely provided by self-induced amplitude modulations generated by pinnae movement. Amplitude variations in the echo not introduced by the moving pinnae can be considered as noise interfering with the localization process. The amplitude of the dominant glints is very stable. Therefore, these parts of the echoes contain very little noise. However, using only the dominant glints potentially comes at a cost. Depending on the flutter rate of the insect, a limited number of dominant glints will be present in each echo giving the bat a limited number of sample points on which to base localization. We evaluate the feasibility of a strategy under which Rhinolophidae use only dominant glints. We use a computational model of the echolocation task faced by Rhinolophidae. Our model includes the spatial filtering of the echoes by the morphology of the sonar apparatus of Rhinolophus rouxii as well as the amplitude modulations introduced by pinnae movements. Using this model, we evaluate whether the dominant glints provide Rhinolophidae with enough information to perform localization. Our simulations show that Rhinolophidae can use dominant glints in the echoes as carriers for self-induced amplitude modulations serving as localization cues. In particular, it is shown that the reduction in noise achieved by using only the dominant glints outweighs the information loss that occurs by sampling the echo.

  5. The Venus Flytrap Dionaea muscipula Counts Prey-Induced Action Potentials to Induce Sodium Uptake.

    Science.gov (United States)

    Böhm, Jennifer; Scherzer, Sönke; Krol, Elzbieta; Kreuzer, Ines; von Meyer, Katharina; Lorey, Christian; Mueller, Thomas D; Shabala, Lana; Monte, Isabel; Solano, Roberto; Al-Rasheid, Khaled A S; Rennenberg, Heinz; Shabala, Sergey; Neher, Erwin; Hedrich, Rainer

    2016-02-08

    Carnivorous plants, such as the Venus flytrap (Dionaea muscipula), depend on an animal diet when grown in nutrient-poor soils. When an insect visits the trap and tilts the mechanosensors on the inner surface, action potentials (APs) are fired. After a moving object elicits two APs, the trap snaps shut, encaging the victim. Panicking preys repeatedly touch the trigger hairs over the subsequent hours, leading to a hermetically closed trap, which via the gland-based endocrine system is flooded by a prey-decomposing acidic enzyme cocktail. Here, we asked the question as to how many times trigger hairs have to be stimulated (e.g., now many APs are required) for the flytrap to recognize an encaged object as potential food, thus making it worthwhile activating the glands. By applying a series of trigger-hair stimulations, we found that the touch hormone jasmonic acid (JA) signaling pathway is activated after the second stimulus, while more than three APs are required to trigger an expression of genes encoding prey-degrading hydrolases, and that this expression is proportional to the number of mechanical stimulations. A decomposing animal contains a sodium load, and we have found that these sodium ions enter the capture organ via glands. We identified a flytrap sodium channel DmHKT1 as responsible for this sodium acquisition, with the number of transcripts expressed being dependent on the number of mechano-electric stimulations. Hence, the number of APs a victim triggers while trying to break out of the trap identifies the moving prey as a struggling Na(+)-rich animal and nutrition for the plant. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. Benthic prey fish assessment, Lake Ontario 2013

    Science.gov (United States)

    Weidel, Brian C.; Walsh, Maureen; Connerton, Michael J.

    2014-01-01

    abundance and weight indices increased slightly as compared to 2012. The number index value of 16.6 was 30% of the maximum number observed in 2008 when the number index was 95.2. Round Goby density estimates from the 2013 fall benthic prey fish survey were 33 times greater than fall Slimy Sculpin density, indicating Round Goby are now the dominant Lake Ontario benthic prey fish.

  7. Toxoplasmosis in prey species and consequences for prevalence in feral cats: not all prey species are equal.

    Science.gov (United States)

    Afonso, E; Thulliez, P; Pontier, D; Gilot-Fromont, E

    2007-12-01

    Toxoplasma gondii is largely transmitted to definitive felid hosts through predation. Not all prey species represent identical risks of infection for cats because of differences in prey susceptibility, exposure and/or lifespan. Previously published studies have shown that prevalence in rodent and lagomorph species is positively correlated with body mass. We tested the hypothesis that different prey species have different infection risks by comparing infection dynamics of feral cats at 4 sites in the sub-Antarctic Kerguelen archipelago which differed in prey availability. Cats were trapped from 1994 to 2004 and anti-T. gondii IgG antibodies were detected using the modified agglutination test (> or =1:40). Overall seroprevalence was 51.09%. Antibody prevalence differed between sites, depending on diet and also on sex, after taking into account the effect of age. Males were more often infected than females and the difference between the sexes tended to be more pronounced in the site where more prey species were available. A difference in predation efficiency between male and female cats may explain this result. Overall, our results suggest that the composition of prey items in cat diet influences the risk of T. gondii infection. Prey compositon should therefore be considered important in any understanding of infection dynamics of T. gondii.

  8. Prey selection by a reintroduced lion population in the Greater ...

    African Journals Online (AJOL)

    Prey selection by a reintroduced lion population in the Greater Makalali Conservancy, South Africa. Dave Druce, Heleen Genis, Jonathan Braak, Sophie Greatwood, Audrey Delsink, Ross Kettles, Luke Hunter, Rob Slotow ...

  9. An investigation into the chemical composition of alternative invertebrate prey

    NARCIS (Netherlands)

    Oonincx, D.G.A.B.; Dierenfeld, E.S.

    2012-01-01

    The aim of this study was to determine the chemical composition of eight invertebrate species and evaluate their suitability as alternative prey. The species selected were rusty red cockroaches (Blatta lateralis), six-spotted cockroaches (Eublaberus distanti), Madagascar hissing cockroaches

  10. Analyses of stomach contents provide information on prey of ...

    African Journals Online (AJOL)

    spamer

    example. In this paper, information is presented on the cephalopods eaten by four species of shark. Initial studies had ..... Their prey selection supports sighting .... 18(1): 27 – 40. KLIMLEY, A. P. 1993 — Highly directional swimming by scal-.

  11. Interaction between Mesodinium rubrum and its prey: importance of prey concentration, irradiance and pH

    DEFF Research Database (Denmark)

    Moldrup, Morten; Hansen, Per Juel

    2007-01-01

    in mixed cultures of M. rubrum and Teleaulax sp. The functional and numerical response study showed that the threshold concentration of the cryptophyte Teleaulax sp. was 50 cells ml-1 and the maximum growth of M. rubrum was 0.23 and 0.49 d-1 for 20 and 100 µE m2 s-1, respectively. Calculation of ingestion...... to starvation showed that M. rubrum could survive for around 50 d without prey. These results are all discussed with respect to M. rubrum's adaptation to its environment....

  12. The effect of habitat structure on prey mortality depends on predator and prey microhabitat use

    Czech Academy of Sciences Publication Activity Database

    Klečka, Jan; Boukal S., David

    2014-01-01

    Roč. 176, č. 1 (2014), s. 183-191 ISSN 0029-8549 R&D Projects: GA ČR GAP505/10/0096 Grant - others:GA JU(CZ) 145/2010/P; EU Marie Curie European Grant(CZ) PERG04-GA-2008-239543 Institutional support: RVO:60077344 Keywords : predation * predator-prey interactions * habitat complexity Subject RIV: EH - Ecology , Behaviour Impact factor: 3.093, year: 2014 http://link.springer.com/article/10.1007%2Fs00442-014-3007-6

  13. Do phytoseiid mites select the best prey species in terms of reproductive success?

    NARCIS (Netherlands)

    Dicke, M.; Sabelis, M.W.; Jong, de M.; Alers, M.P.T.

    1990-01-01

    Optimal foraging theory predicts that predators prefer those prey species that are most rewarding in terms of reproductive success, which is dependent on prey quality and prey availability. To investigate which selection pressures may have moulded prey preference in an acarine system consisting of

  14. Influence of prey body characteristics and performance on predator selection.

    Science.gov (United States)

    Holmes, Thomas H; McCormick, Mark I

    2009-03-01

    At the time of settlement to the reef environment, coral reef fishes differ in a number of characteristics that may influence their survival during a predatory encounter. This study investigated the selective nature of predation by both a multi-species predator pool, and a single common predator (Pseudochromis fuscus), on the reef fish, Pomacentrus amboinensis. The study focused on the early post-settlement period of P. amboinensis, when mortality, and hence selection, is known to be highest. Correlations between nine different measures of body condition/performance were examined at the time of settlement, in order to elucidate the relationships between different traits. Single-predator (P. fuscus) choice trials were conducted in 57.4-l aquaria with respect to three different prey characteristics [standard length (SL), body weight and burst swimming speed], whilst multi-species trials were conducted on open patch reefs, manipulating prey body weight only. Relationships between the nine measures of condition/performance were generally poor, with the strongest correlations occurring between the morphological measures and within the performance measures. During aquaria trials, P. fuscus was found to be selective with respect to prey SL only, with larger individuals being selected significantly more often. Multi-species predator communities, however, were selective with respect to prey body weight, with heavier individuals being selected significantly more often than their lighter counterparts. Our results suggest that under controlled conditions, body length may be the most important prey characteristic influencing prey survival during predatory encounters with P. fuscus. In such cases, larger prey size may actually be a distinct disadvantage to survival. However, these relationships appear to be more complex under natural conditions, where the expression of prey characteristics, the selectivity fields of a number of different predators, their relative abundance, and

  15. Mountain lions prey selectively on prion-infected mule deer

    OpenAIRE

    Krumm, Caroline E.; Conner, Mary M.; Hobbs, N. Thompson; Hunter, Don O.; Miller, Michael W.

    2009-01-01

    The possibility that predators choose prey selectively based on age or condition has been suggested but rarely tested. We examined whether mountain lions (Puma concolor) selectively prey upon mule deer (Odocoileus hemionus) infected with chronic wasting disease, a prion disease. We located kill sites of mountain lions in the northern Front Range of Colorado, USA, and compared disease prevalence among lion-killed adult (?2 years old) deer with prevalence among sympatric deer taken by hunters i...

  16. The Dynamical Analysis of a Prey-Predator Model with a Refuge-Stage Structure Prey Population

    Directory of Open Access Journals (Sweden)

    Raid Kamel Naji

    2016-01-01

    Full Text Available We proposed and analyzed a mathematical model dealing with two species of prey-predator system. It is assumed that the prey is a stage structure population consisting of two compartments known as immature prey and mature prey. It has a refuge capability as a defensive property against the predation. The existence, uniqueness, and boundedness of the solution of the proposed model are discussed. All the feasible equilibrium points are determined. The local and global stability analysis of them are investigated. The occurrence of local bifurcation (such as saddle node, transcritical, and pitchfork near each of the equilibrium points is studied. Finally, numerical simulations are given to support the analytic results.

  17. The infrared retina

    International Nuclear Information System (INIS)

    Krishna, Sanjay

    2009-01-01

    As infrared imaging systems have evolved from the first generation of linear devices to the second generation of small format staring arrays to the present 'third-gen' systems, there is an increased emphasis on large area focal plane arrays (FPAs) with multicolour operation and higher operating temperature. In this paper, we discuss how one needs to develop an increased functionality at the pixel level for these next generation FPAs. This functionality could manifest itself as spectral, polarization, phase or dynamic range signatures that could extract more information from a given scene. This leads to the concept of an infrared retina, which is an array that works similarly to the human eye that has a 'single' FPA but multiple cones, which are photoreceptor cells in the retina of the eye that enable the perception of colour. These cones are then coupled with powerful signal processing techniques that allow us to process colour information from a scene, even with a limited basis of colour cones. Unlike present day multi or hyperspectral systems, which are bulky and expensive, the idea would be to build a poor man's 'infrared colour' camera. We use examples such as plasmonic tailoring of the resonance or bias dependent dynamic tuning based on quantum confined Stark effect or incorporation of avalanche gain to achieve embodiments of the infrared retina.

  18. Do lions Panthera leo actively select prey or do prey preferences simply reflect chance responses via evolutionary adaptations to optimal foraging?

    Directory of Open Access Journals (Sweden)

    Matt W Hayward

    Full Text Available Research on coursing predators has revealed that actions throughout the predatory behavioral sequence (using encounter rate, hunting rate, and kill rate as proxy measures of decisions drive observed prey preferences. We tested whether similar actions drive the observed prey preferences of a stalking predator, the African lion Panthera leo. We conducted two 96 hour, continuous follows of lions in Addo Elephant National Park seasonally from December 2003 until November 2005 (16 follows, and compared prey encounter rate with prey abundance, hunt rate with prey encounter rate, and kill rate with prey hunt rate for the major prey species in Addo using Jacobs' electivity index. We found that lions encountered preferred prey species far more frequently than expected based on their abundance, and they hunted these species more frequently than expected based on this higher encounter rate. Lions responded variably to non-preferred and avoided prey species throughout the predatory sequence, although they hunted avoided prey far less frequently than expected based on the number of encounters of them. We conclude that actions of lions throughout the predatory behavioural sequence, but particularly early on, drive the prey preferences that have been documented for this species. Once a hunt is initiated, evolutionary adaptations to the predator-prey interactions drive hunting success.

  19. Do lions Panthera leo actively select prey or do prey preferences simply reflect chance responses via evolutionary adaptations to optimal foraging?

    Science.gov (United States)

    Hayward, Matt W; Hayward, Gina J; Tambling, Craig J; Kerley, Graham I H

    2011-01-01

    Research on coursing predators has revealed that actions throughout the predatory behavioral sequence (using encounter rate, hunting rate, and kill rate as proxy measures of decisions) drive observed prey preferences. We tested whether similar actions drive the observed prey preferences of a stalking predator, the African lion Panthera leo. We conducted two 96 hour, continuous follows of lions in Addo Elephant National Park seasonally from December 2003 until November 2005 (16 follows), and compared prey encounter rate with prey abundance, hunt rate with prey encounter rate, and kill rate with prey hunt rate for the major prey species in Addo using Jacobs' electivity index. We found that lions encountered preferred prey species far more frequently than expected based on their abundance, and they hunted these species more frequently than expected based on this higher encounter rate. Lions responded variably to non-preferred and avoided prey species throughout the predatory sequence, although they hunted avoided prey far less frequently than expected based on the number of encounters of them. We conclude that actions of lions throughout the predatory behavioural sequence, but particularly early on, drive the prey preferences that have been documented for this species. Once a hunt is initiated, evolutionary adaptations to the predator-prey interactions drive hunting success.

  20. Disentangling mite predator-prey relationships by multiplex PCR.

    Science.gov (United States)

    Pérez-Sayas, Consuelo; Pina, Tatiana; Gómez-Martínez, María A; Camañes, Gemma; Ibáñez-Gual, María V; Jaques, Josep A; Hurtado, Mónica A

    2015-11-01

    Gut content analysis using molecular techniques can help elucidate predator-prey relationships in situations in which other methodologies are not feasible, such as in the case of trophic interactions between minute species such as mites. We designed species-specific primers for a mite community occurring in Spanish citrus orchards comprising two herbivores, the Tetranychidae Tetranychus urticae and Panonychus citri, and six predatory mites belonging to the Phytoseiidae family; these predatory mites are considered to be these herbivores' main biological control agents. These primers were successfully multiplexed in a single PCR to test the range of predators feeding on each of the two prey species. We estimated prey DNA detectability success over time (DS50), which depended on the predator-prey combination and ranged from 0.2 to 18 h. These values were further used to weight prey detection in field samples to disentangle the predatory role played by the most abundant predators (i.e. Euseius stipulatus and Phytoseiulus persimilis). The corrected predation value for E. stipulatus was significantly higher than for P. persimilis. However, because this 1.5-fold difference was less than that observed regarding their sevenfold difference in abundance, we conclude that P. persimilis is the most effective predator in the system; it preyed on tetranychids almost five times more frequently than E. stipulatus did. The present results demonstrate that molecular tools are appropriate to unravel predator-prey interactions in tiny species such as mites, which include important agricultural pests and their predators. © 2015 John Wiley & Sons Ltd.

  1. Prey handling using whole-body fluid dynamics in batoids.

    Science.gov (United States)

    Wilga, Cheryl D; Maia, Anabela; Nauwelaerts, Sandra; Lauder, George V

    2012-02-01

    Fluid flow generated by body movements is a foraging tactic that has been exploited by many benthic species. In this study, the kinematics and hydrodynamics of prey handling behavior in little skates, Leucoraja erinacea, and round stingrays, Urobatis halleri, are compared using kinematics and particle image velocimetry. Both species use the body to form a tent to constrain the prey with the pectoral fin edges pressed against the substrate. Stingrays then elevate the head, which increases the volume between the body and the substrate to generate suction, while maintaining pectoral fin contact with the substrate. Meanwhile, the tip of the rostrum is curled upwards to create an opening where fluid is drawn under the body, functionally analogous to suction-feeding fishes. Skates also rotate the rostrum upwards although with the open rostral sides and the smaller fin area weaker fluid flow is generated. However, skates also use a rostral strike behavior in which the rostrum is rapidly rotated downwards pushing fluid towards the substrate to potentially stun or uncover prey. Thus, both species use the anterior portion of the body to direct fluid flow to handle prey albeit in different ways, which may be explained by differences in morphology. Rostral stiffness and pectoral fin insertion onto the rostrum differ between skates and rays and this corresponds to behavioral differences in prey handling resulting in distinct fluid flow patterns. The flexible muscular rostrum and greater fin area of stingrays allow more extensive use of suction to handle prey while the stiff cartilaginous rostrum of skates lacking extensive fin insertion is used as a paddle to strike prey as well as to clear away sand cover. Copyright © 2011 Elsevier GmbH. All rights reserved.

  2. Biomechanics of predator-prey arms race in lion, zebra, cheetah and impala

    Science.gov (United States)

    Wilson, Alan M.; Hubel, Tatjana Y.; Wilshin, Simon D.; Lowe, John C.; Lorenc, Maja; Dewhirst, Oliver P.; Bartlam-Brooks, Hattie L. A.; Diack, Rebecca; Bennitt, Emily; Golabek, Krystyna A.; Woledge, Roger C.; McNutt, J. Weldon; Curtin, Nancy A.; West, Timothy G.

    2018-02-01

    The fastest and most manoeuvrable terrestrial animals are found in savannah habitats, where predators chase and capture running prey. Hunt outcome and success rate are critical to survival, so both predator and prey should evolve to be faster and/or more manoeuvrable. Here we compare locomotor characteristics in two pursuit predator-prey pairs, lion-zebra and cheetah-impala, in their natural savannah habitat in Botswana. We show that although cheetahs and impalas were universally more athletic than lions and zebras in terms of speed, acceleration and turning, within each predator-prey pair, the predators had 20% higher muscle fibre power than prey, 37% greater acceleration and 72% greater deceleration capacity than their prey. We simulated hunt dynamics with these data and showed that hunts at lower speeds enable prey to use their maximum manoeuvring capacity and favour prey survival, and that the predator needs to be more athletic than its prey to sustain a viable success rate.

  3. Simultaneous determination of penicillin G salts by infrared spectroscopy: Evaluation of combining orthogonal signal correction with radial basis function-partial least squares regression

    Science.gov (United States)

    Talebpour, Zahra; Tavallaie, Roya; Ahmadi, Seyyed Hamid; Abdollahpour, Assem

    2010-09-01

    In this study, a new method for the simultaneous determination of penicillin G salts in pharmaceutical mixture via FT-IR spectroscopy combined with chemometrics was investigated. The mixture of penicillin G salts is a complex system due to similar analytical characteristics of components. Partial least squares (PLS) and radial basis function-partial least squares (RBF-PLS) were used to develop the linear and nonlinear relation between spectra and components, respectively. The orthogonal signal correction (OSC) preprocessing method was used to correct unexpected information, such as spectral overlapping and scattering effects. In order to compare the influence of OSC on PLS and RBF-PLS models, the optimal linear (PLS) and nonlinear (RBF-PLS) models based on conventional and OSC preprocessed spectra were established and compared. The obtained results demonstrated that OSC clearly enhanced the performance of both RBF-PLS and PLS calibration models. Also in the case of some nonlinear relation between spectra and component, OSC-RBF-PLS gave satisfactory results than OSC-PLS model which indicated that the OSC was helpful to remove extrinsic deviations from linearity without elimination of nonlinear information related to component. The chemometric models were tested on an external dataset and finally applied to the analysis commercialized injection product of penicillin G salts.

  4. The hydrodynamics of predator-prey interactions in zebrafish

    Science.gov (United States)

    McHenry, Matthew; Soto, Alberto; Carrillo, Andres; Byron, Margaret

    2017-11-01

    Hydrodynamics govern the behavior of fishes when they operate as predators or prey. In addition to the role of fluid forces in propulsion, fishes relay on flow stimuli to sense a predatory threat and to localize palatable prey. We have performed a series of experiments on zebrafish (Danio rerio) that aim to resolve the major factors that determine whether prey survive an encounter with a predator. Zebrafish serve as a model system in this pursuit because the adults prey on larvae of the same species and the larvae are often successful in evading the attacks of the adults. We use a combination of theoretical and experimental approaches to resolve the behavioral algorithms and kinematics that determined the outcome of these interactions. In this context, the hydrodynamics of intermediate Reynolds numbers largely determines the range of flow stimuli and the limits to locomotor performance at dictate prey survival. These principles have the potential to apply to a broad diversity of fishes and other aquatic animals. ONR: N00014-15-1-2249.

  5. Sequential assessment of prey through the use of multiple sensory cues by an eavesdropping bat

    Science.gov (United States)

    Page, Rachel A.; Schnelle, Tanja; Kalko, Elisabeth K. V.; Bunge, Thomas; Bernal, Ximena E.

    2012-06-01

    Predators are often confronted with a broad diversity of potential prey. They rely on cues associated with prey quality and palatability to optimize their hunting success and to avoid consuming toxic prey. Here, we investigate a predator's ability to assess prey cues during capture, handling, and consumption when confronted with conflicting information about prey quality. We used advertisement calls of a preferred prey item (the túngara frog) to attract fringe-lipped bats, Trachops cirrhosus, then offered palatable, poisonous, and chemically manipulated anurans as prey. Advertisement calls elicited an attack response, but as bats approached, they used additional sensory cues in a sequential manner to update their information about prey size and palatability. While both palatable and poisonous small anurans were readily captured, large poisonous toads were approached but not contacted suggesting the use of echolocation for assessment of prey size at close range. Once prey was captured, bats used chemical cues to make final, post-capture decisions about whether to consume the prey. Bats dropped small, poisonous toads as well as palatable frogs coated in toad toxins either immediately or shortly after capture. Our study suggests that echolocation and chemical cues obtained at close range supplement information obtained from acoustic cues at long range. Updating information about prey quality minimizes the occurrence of costly errors and may be advantageous in tracking temporal and spatial fluctuations of prey and exploiting novel food sources. These findings emphasize the sequential, complex nature of prey assessment that may allow exploratory and flexible hunting behaviors.

  6. Prey size selection and cannibalistic behaviour of juvenile barramundi Lates calcarifer.

    Science.gov (United States)

    Ribeiro, F F; Qin, J G

    2015-05-01

    This study assessed the cannibalistic behaviour of juvenile barramundi Lates calcarifer and examined the relationship between prey size selection and energy gain of cannibals. Prey handling time and capture success by cannibals were used to estimate the ratio of energy gain to energy cost in prey selection. Cannibals selected smaller prey despite its capability of ingesting larger prey individuals. In behavioural analysis, prey handling time significantly increased with prey size, but it was not significantly affected by cannibal size. Conversely, capture success significantly decreased with the increase of both prey and cannibal sizes. The profitability indices showed that the smaller prey provides the most energy return for cannibals of all size classes. These results indicate that L. calcarifer cannibals select smaller prey for more profitable return. The behavioural analysis, however, indicates that L. calcarifer cannibals attack prey of all size at a similar rate but ingest smaller prey more often, suggesting that prey size selection is passively orientated rather than at the predator's choice. The increase of prey escape ability and morphological constraint contribute to the reduction of intracohort cannibalism as fish grow larger. This study contributes to the understanding of intracohort cannibalism and development of strategies to reduce fish cannibalistic mortalities. © 2015 The Fisheries Society of the British Isles.

  7. Comparative growth and development of spiders reared on live and dead prey.

    Science.gov (United States)

    Peng, Yu; Zhang, Fan; Gui, Shaolan; Qiao, Huping; Hose, Grant C

    2013-01-01

    Scavenging (feeding on dead prey) has been demonstrated across a number of spider families, yet the implications of feeding on dead prey for the growth and development of individuals and population is unknown. In this study we compare the growth, development, and predatory activity of two species of spiders that were fed on live and dead prey. Pardosa astrigera (Lycosidae) and Hylyphantes graminicola (Lyniphiidae) were fed live or dead fruit flies, Drosophila melanogaster. The survival of P. astrigera and H. graminicola was not affected by prey type. The duration of late instars of P. astrigera fed dead prey were longer and mature spiders had less protein content than those fed live prey, whereas there were no differences in the rate of H. graminicola development, but the mass of mature spiders fed dead prey was greater than those fed live prey. Predation rates by P. astrigera did not differ between the two prey types, but H. graminicola had a higher rate of predation on dead than alive prey, presumably because the dead flies were easier to catch and handle. Overall, the growth, development and reproduction of H. graminicola reared with dead flies was better than those reared on live flies, yet for the larger P. astrigera, dead prey may suit smaller instars but mature spiders may be best maintained with live prey. We have clearly demonstrated that dead prey may be suitable for rearing spiders, although the success of the spiders fed such prey appears size- and species specific.

  8. Fear on the move: predator hunting mode predicts variation in prey mortality and plasticity in prey spatial response.

    Science.gov (United States)

    Miller, Jennifer R B; Ament, Judith M; Schmitz, Oswald J

    2014-01-01

    Ecologists have long searched for a framework of a priori species traits to help predict predator-prey interactions in food webs. Empirical evidence has shown that predator hunting mode and predator and prey habitat domain are useful traits for explaining predator-prey interactions. Yet, individual experiments have yet to replicate predator hunting mode, calling into question whether predator impacts can be attributed to hunting mode or merely species identity. We tested the effects of spider predators with sit-and-wait, sit-and-pursue and active hunting modes on grasshopper habitat domain, activity and mortality in a grassland system. We replicated hunting mode by testing two spider predator species of each hunting mode on the same grasshopper prey species. We observed grasshoppers with and without each spider species in behavioural cages and measured their mortality rates, movements and habitat domains. We likewise measured the movements and habitat domains of spiders to characterize hunting modes. We found that predator hunting mode explained grasshopper mortality and spider and grasshopper movement activity and habitat domain size. Sit-and-wait spider predators covered small distances over a narrow domain space and killed fewer grasshoppers than sit-and-pursue and active predators, which ranged farther distances across broader domains and killed more grasshoppers, respectively. Prey adjusted their activity levels and horizontal habitat domains in response to predator presence and hunting mode: sedentary sit-and-wait predators with narrow domains caused grasshoppers to reduce activity in the same-sized domain space; more mobile sit-and-pursue predators with broader domains caused prey to reduce their activity within a contracted horizontal (but not vertical) domain space; and highly mobile active spiders led grasshoppers to increase their activity across the same domain area. All predators impacted prey activity, and sit-and-pursue predators generated strong

  9. Feeding behaviour of the nauplii of the marine calanoid copepod Paracartia grani Sars: Functional response, prey size spectrum, and effects of the presence of alternative prey.

    Directory of Open Access Journals (Sweden)

    Laura K Helenius

    Full Text Available Laboratory feeding experiments were conducted to study the functional response and prey size spectrum of the young naupliar stages of the calanoid copepod Paracartia grani Sars. Experiments were conducted on a range of microalgal prey of varying sizes and motility patterns. Significant feeding was found in all prey of a size range of 4.5-19.8 μm, with Holling type III functional responses observed for most prey types. The highest clearance rates occurred when nauplii fed on the dinoflagellate Heterocapsa sp. and the diatom Thalassiosira weissflogii (respectively, 0.61 and 0.70 mL ind-1 d-1, suggesting an optimal prey:predator ratio of 0.09. Additional experiments were conducted to examine the effects of the presence of alternative prey (either Heterocapsa sp. or Gymnodinium litoralis on the functional response to the haptophyte Isochrysis galbana. In the bialgal mixtures, clearance and ingestion rates of I. galbana along the range of the functional response were significantly reduced as a result of selectivity towards the larger, alternative prey. Paradoxically, relatively large prey trigger a perception response in the nauplii, but most likely such prey cannot be completely ingested and a certain degree of sloppy feeding may occur. Our results are further evidence of the complex prey-specific feeding interactions that are likely to occur in natural assemblages with several available prey types.

  10. On multi-team predator-prey models

    International Nuclear Information System (INIS)

    Elettreby, M.F.; Saker, S.H.; Ahmed, E.

    2005-05-01

    Many creatures form teams. This has, at least, two main advantages: the first is the improvement in foraging, since looking for food in a team is more efficient than doing it alone. The second is that living in a team reduces predation risk due to early spotting of predators and that existing in a team gives a higher probability that the predator will attack another member of the team. In this paper models are given where two teams of predators interact with two teams of preys. The teams of each group (predators or preys) help each other. In this paper we propose three different versions of the multi-team predator prey model. We study the equilibrium solutions, the conditions of their local asymptotic stability, persistence and the global stability of the solution of one of the models. Some numerical simulations are done. (author)

  11. Influence of poisoned prey on foraging behavior of ferruginous hawks

    Science.gov (United States)

    Vyas, Nimish B.; Kuncir, Frank; Clinton, Criss C.

    2017-01-01

    We recorded 19 visits by ferruginous hawks (Buteo regalis) over 6 d at two black–tailed prairie dog (Cynomys ludovicianus) subcolonies poisoned with the rodenticide Rozol® Prairie Dog Bait (0.005% chlorophacinone active ingredient) and at an adjacent untreated subcolony. Before Rozol® application ferruginous hawks foraged in the untreated and treated subcolonies but after Rozol® application predation by ferruginous hawks was only observed in the treated subcolonies. We suggest that ferruginous hawks' preference for hunting in the treated subcolonies after Rozol® application was influenced by the availability of easy-to-capture prey, presumably due to Rozol® poisoning. The energetically beneficial behavior of favoring substandard prey may increase raptor encounters with rodenticide exposed animals if prey vulnerability has resulted from poisoning.

  12. Release from prey preservation behavior via prey switch allowed diversification of cuticular hydrocarbon profiles in digger wasps.

    Science.gov (United States)

    Wurdack, Mareike; Polidori, Carlo; Keller, Alexander; Feldhaar, Heike; Schmitt, Thomas

    2017-11-01

    The cuticle of insects is covered by a layer of hydrocarbons (CHC), whose original function is the protection from desiccation and pathogens. However, in most insects CHC profiles are species specific. While this variability among species was largely linked to communication and recognition functions, additional selective forces may shape insect CHC profiles. Here, we show that in Philanthinae digger wasps (Crabronidae) the CHC profile coevolved with a peculiar brood-care strategy. In particular, we found that the behavior to embalm prey stored in the nest with hydrocarbons is adaptive to protect larval food from fungi in those species hunting for Hymenoptera. The prey embalming secretion is identical in composition to the alkene-dominated CHC profile in these species, suggesting that their profile is adaptively conserved for this purpose. In contrast, prey embalming is not required in those species that switched to Coleoptera as prey. Released from this chemical brood-care strategy, Coleoptera-hunting species considerably diversified their CHC profiles. Differential needs to successfully protect prey types used as larval food have thus driven the diversification of CHCs profiles of female Philanthinae wasps. To the best of our knowledge, this is the first evidence of a direct link between selection pressure for food preservation and CHC diversity. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  13. Kinetics of infrared stimulated luminescence from feldspars

    DEFF Research Database (Denmark)

    Jain, Mayank; Sohbati, Reza; Guralnik, Benny

    2015-01-01

    thermal and optical, of the infrared stimulated luminescence signal from feldspar. Based on the application of this model, it is concluded that different infra-red stimulated luminescence emissions (UV, blue, yellow and far-red) follow the same kinetics, and, therefore, involve participation of the same...

  14. Josephson effect far-infrared detector

    International Nuclear Information System (INIS)

    Shapiro, S.

    1971-01-01

    Four Josephson effect schemes for detection of far-infrared radiation are reviewed: Video broad-band detection, regenerative detection, conventional mixing for monochromatic signals, and self-mixing or frequency conversion. (U.S.)

  15. Revealing the role of predator interference in a predator-prey system with disease in prey population

    DEFF Research Database (Denmark)

    Chakraborty, Subhendu; Kooi, B.W.; Biswas, B.

    2015-01-01

    Predation on a species subjected to an infectious disease can affect both the infection level and the population dynamics. There is an ongoing debate about the act of managing disease in natural populations through predation. Recent theoretical and empirical evidence shows that predation...... on infected populations can have both positive and negative influences on disease in prey populations. Here, we present a predator-prey system where the prey population is subjected to an infectious disease to explore the impact of predator on disease dynamics. Specifically, we investigate how...... on the strength of interference among predators, predators enhance or control disease outbreaks and population persistence. Moreover, the presence of multistable regimes makes the system very sensitive to perturbations and facilitates a number of regime shifts. Since, the habitat structure and the choice...

  16. Predator-Prey Dynamics in the Mesopelagic: Odontocete Foraging Ecology and Anti-predator Behavior of Prey

    Science.gov (United States)

    Benoit-Bird, K. J.

    2016-02-01

    We explored the behavior of Risso's dolphins foraging in scattering layers off California using an integrated approach comprising echosounders deployed in a deep-diving autonomous underwater vehicle, ship based acoustics, visual observations, direct prey sampling, and animal-borne tags on deep-diving predators. We identified three distinct prey layers: a persistent layer around 425 m, a vertically migrating layer around 300 m, and a layer intermittently present near 50 m, all of which were used by individual tagged animals. Active acoustic measurements demonstrated that Risso's dolphins dove to discrete prey layers throughout the day and night with only slightly higher detection rates at night. Dolphins were detected in all three layers during the day with over half of detections in the middle layer, 20% of detections in the deepest layer, and 10% falling outside the main layers. Dolphins were found less frequently in areas where the shallow, intermittent layer was absent, suggesting that this layer, while containing the smallest prey and the lowest densities of squid, was an important component of their foraging strategy. The deepest layer was targeted equally both during the day and at night. Using acoustic data collected from the AUV, we found layers were made up of distinct, small patches of animals of similar size and taxonomy adjacent to contrasting patches. Squid made up over 70% of the patches in which dolphins were found and more than 95% of those in deep water. Squid targeted by dolphins in deep water were also relatively large, indicating significant benefit from these relatively rare, physically demanding dives. Within these patches, prey formed tighter aggregations when Risso's dolphins were present. Careful integration of a suite of traditional and novel tools is providing insight into the ecology and dynamics of predator and prey in the mesopelagic.

  17. Is the red spotted green frog Hypsiboas punctatus (Anura: Hylidae) selecting its preys? The importance of prey availability.

    Science.gov (United States)

    López, Javier A; Scarabotti, Pablo A; Medrano, María C; Ghirardi, Romina

    2009-09-01

    The study of the feeding ecology of amphibians is an old issue in herpetology. Notwithstanding, the lack of food resources data in many studies of amphibians feeding has lead to partial understanding of frog feeding strategies. In this study we evaluate the trophic selectivity of a red spotted green frog (Hypsiboas punctatus) population from a Middle Paraná River floodplain pond in Argentina, and discuss the importance of prey availability data when interpreting results from diet analysis. We analyzed the gut contents of 47 H. punctatus adults and compared frog's diet with the environmental food resources. Prey availability was estimated by systematically seep-netting the microhabitat where anurans were localized foraging. We identified 33 taxonomic categories from gastrointestinal contents. Numerically, the most important prey categories were dipterans, followed by hemipterans, homopterans and coleopterans. The diet similarity between males and females was high and no statistical differences in diet composition were found. The most abundant food resources in the environment were dipterans, coleopterans, homopterans and collembolans. In order to assess whether frogs were selecting their preys, we calculated Pianka's niche overlap index and Jacobs' electivity index comparing gut contents to prey availability data. Trophic niche overlap was medium but significantly higher than expected by chance. The electivity index indicated that H. punctatus foraged dipterans slightly above their environmental abundance. Among the secondary preys, hemipterans were foraged selectively, homopterans were consumed in the same proportion to their occurrence in the environment, coleopterans were foraged quite under their availability and collembolans were practically ignored by frogs. Without food resources data, H. punctatus could be classified as a specialist feeder, but dipterans also were quite abundant in the environment. Our results show that H. punctatus fit better as a

  18. Bifurcations and feedback control of a stage-structure exploited prey ...

    African Journals Online (AJOL)

    user

    Here, we have considered a stage structure prey-predator model with stage structure for ... N over the prey ,N β is the transition rate from mature predator population 2 ...... Mathematical Bioeconomics: The Optimal Management of Renewable ...

  19. An Objective Approach to Determining the Weight Ranges of Prey Preferred by and Accessible to the Five Large African Carnivores

    OpenAIRE

    Clements, Hayley S.; Tambling, Craig J.; Hayward, Matt W.; Kerley, Graham I. H.

    2014-01-01

    Broad-scale models describing predator prey preferences serve as useful departure points for understanding predator-prey interactions at finer scales. Previous analyses used a subjective approach to identify prey weight preferences of the five large African carnivores, hence their accuracy is questionable. This study uses a segmented model of prey weight versus prey preference to objectively quantify the prey weight preferences of the five large African carnivores. Based on simulations of kno...

  20. Infrared Heaters

    Science.gov (United States)

    1979-01-01

    The heating units shown in the accompanying photos are Panelbloc infrared heaters, energy savers which burn little fuel in relation to their effective heat output. Produced by Bettcher Manufacturing Corporation, Cleveland, Ohio, Panelblocs are applicable to industrial or other facilities which have ceilings more than 12 feet high, such as those pictured: at left the Bare Hills Tennis Club, Baltimore, Maryland and at right, CVA Lincoln- Mercury, Gaithersburg, Maryland. The heaters are mounted high above the floor and they radiate infrared energy downward. Panelblocs do not waste energy by warming the surrounding air. Instead, they beam invisible heat rays directly to objects which absorb the radiation- people, floors, machinery and other plant equipment. All these objects in turn re-radiate the energy to the air. A key element in the Panelbloc design is a coating applied to the aluminized steel outer surface of the heater. This coating must be corrosion resistant at high temperatures and it must have high "emissivity"-the ability of a surface to emit radiant energy. The Bettcher company formerly used a porcelain coating, but it caused a production problem. Bettcher did not have the capability to apply the material in its own plant, so the heaters had to be shipped out of state for porcelainizing, which entailed extra cost. Bettcher sought a coating which could meet the specifications yet be applied in its own facilities. The company asked The Knowledge Availability Systems Center, Pittsburgh, Pennsylvania, a NASA Industrial Applications Center (IAC), for a search of NASA's files

  1. Trait-mediated diversification in nematode predator–prey systems

    NARCIS (Netherlands)

    Mulder, C.; Helder, J.; Vervoort, M.T.W.; Vonk, J.A.

    2011-01-01

    Nematodes are presumably the most numerous Metazoans in terrestrial habitats. They are represented at all trophic levels and are known to respond to nutrient limitation, prey availability, and microbial resources. Predatory nematodes reside at the highest trophic level, and as such their feeding

  2. Does colour polymorphism enhance survival of prey populations?

    Science.gov (United States)

    Wennersten, Lena; Forsman, Anders

    2009-01-01

    That colour polymorphism may protect prey populations from predation is an old but rarely tested hypothesis. We examine whether colour polymorphic populations of prey exposed to avian predators in an ecologically valid visual context were exposed to increased extinction risk compared with monomorphic populations. We made 2976 artificial pastry prey, resembling Lepidoptera larvae, in four different colours and presented them in 124 monomorphic and 124 tetramorphic populations on tree trunks and branches such that they would be exposed to predation by free-living birds, and monitored their ‘survival’. Among monomorphic populations, there was a significant effect of prey coloration on survival, confirming that coloration influenced susceptibility to visually oriented predators. Survival of polymorphic populations was inferior to that of monomorphic green populations, but did not differ significantly from monomorphic brown, yellow or red populations. Differences in survival within polymorphic populations paralleled those seen among monomorphic populations; the red morph most frequently went extinct first and the green morph most frequently survived the longest. Our findings do not support the traditional protective polymorphism hypothesis and are in conflict with those of earlier studies. As a possible explanation to our findings, we offer a competing ‘giveaway cue’ hypothesis: that polymorphic populations may include one morph that attracts the attention of predators and that polymorphic populations therefore may suffer increased predation compared with some monomorphic populations. PMID:19324729

  3. Prey, but not plant, chemical discrimination by the lizard ...

    African Journals Online (AJOL)

    We experimentally studied responses to food chemicals by Gerrhosaurus nigrolineatus, amember of a lizard genus endemic to subsaharan Africa. Gerrhosaur diets vary from insectivorous to omnivorous with a very large plant portion. The omnivorous G. validus responds strongly to chemical cues from prey and food plants.

  4. Echolocating bats cry out loud to detect their prey

    DEFF Research Database (Denmark)

    Surlykke, Annemarie; Kalko, Elisabeth K V

    2008-01-01

    Echolocating bats have successfully exploited a broad range of habitats and prey. Much research has demonstrated how time-frequency structure of echolocation calls of different species is adapted to acoustic constraints of habitats and foraging behaviors. However, the intensity of bat calls has b...

  5. Hydrodynamics of prey capture in sharks : effects of substrate

    NARCIS (Netherlands)

    Nauwelaerts, Sandra; Wilga, Cheryl; Sanford, Christopher; Lauder, George

    2007-01-01

    In suction feeding, a volume of water is drawn into the mouth of a predator. Previous studies of suction feeding in fishes have shown that significant fluid velocities are confined to a region within one mouth width from the mouth. Therefore, the predator must be relatively close to the prey to

  6. Direct identification of predator-prey dynamics in gyrokinetic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Sumire, E-mail: sumire.kobayashi@lpp.polytechnique.fr; Gürcan, Özgür D [Laboratoire de Physique des Plasmas, CNRS, Paris-Sud, Ecole Polytechnique, UMR7648, F-91128 Palaiseau (France); Diamond, Patrick H. [University of California, San Diego, La Jolla, California 92093-0319 (United States)

    2015-09-15

    The interaction between spontaneously formed zonal flows and small-scale turbulence in nonlinear gyrokinetic simulations is explored in a shearless closed field line geometry. It is found that when clear limit cycle oscillations prevail, the observed turbulent dynamics can be quantitatively captured by a simple Lotka-Volterra type predator-prey model. Fitting the time traces of full gyrokinetic simulations by such a reduced model allows extraction of the model coefficients. Scanning physical plasma parameters, such as collisionality and density gradient, it was observed that the effective growth rates of turbulence (i.e., the prey) remain roughly constant, in spite of the higher and varying level of primary mode linear growth rates. The effective growth rate that was extracted corresponds roughly to the zonal-flow-modified primary mode growth rate. It was also observed that the effective damping of zonal flows (i.e., the predator) in the parameter range, where clear predator-prey dynamics is observed, (i.e., near marginal stability) agrees with the collisional damping expected in these simulations. This implies that the Kelvin-Helmholtz-like instability may be negligible in this range. The results imply that when the tertiary instability plays a role, the dynamics becomes more complex than a simple Lotka-Volterra predator prey.

  7. Prey capture success and chick diet of Damara terns Sterna ...

    African Journals Online (AJOL)

    Feeding terns are affected by a variety of environmental conditions. We studied prey capture success of Damara terns Sterna balaenarum in relation to six variables at two breeding colonies in southern Namibia: tidal phase, wind speed, water clarity, cloud cover, water depth and locality. Damara terns dived most ...

  8. Insectivorous birds eavesdrop on the pheromones of their prey.

    Science.gov (United States)

    Saavedra, Irene; Amo, Luisa

    2018-01-01

    Chemical cues play a fundamental role in mate attraction and mate choice. Lepidopteran females, such as the winter moth (Operophtera brumata), emit pheromones to attract males in the reproductive period. However, these chemical cues could also be eavesdropped by predators. To our knowledge, no studies have examined whether birds can detect pheromones of their prey. O. brumata adults are part of the winter diet of some insectivorous tit species, such as the great tit (Parus major) and blue tit (Cyanistes caeruleus). We performed a field experiment aimed to disentangle whether insectivorous birds can exploit the pheromones emitted by their prey for prey location. We placed artificial larvae and a dispenser on branches of Pyrenean oak trees (Quercus pyrenaica). In half of the trees we placed an O. brumata pheromone dispenser and in the other half we placed a control dispenser. We measured the predation rate of birds on artificial larvae. Our results show that more trees had larvae with signs of avian predation when they contained an O. brumata pheromone than when they contained a control dispenser. Furthermore, the proportion of artificial larvae with signs of avian predation was greater in trees that contained the pheromone than in control trees. Our results indicate that insectivorous birds can exploit the pheromones emitted by moth females to attract males, as a method of prey detection. These results highlight the potential use of insectivorous birds in the biological control of insect pests.

  9. Chapter 22: Marbled Murrelet Food Habits and Prey Ecology

    Science.gov (United States)

    Esther E. Burkett

    1995-01-01

    Information on food habits of the Marbled Murrelet (Brachyramphus marmoratus) was compiled from systematic studies and anecdotal reports from Alaska to California. Major differences between the winter and summer diets were apparent, with euphausiids and mysids becoming more dominant during winter and spring. The primary invertebrate prey items were...

  10. Stochastic population oscillations in spatial predator-prey models

    International Nuclear Information System (INIS)

    Taeuber, Uwe C

    2011-01-01

    It is well-established that including spatial structure and stochastic noise in models for predator-prey interactions invalidates the classical deterministic Lotka-Volterra picture of neutral population cycles. In contrast, stochastic models yield long-lived, but ultimately decaying erratic population oscillations, which can be understood through a resonant amplification mechanism for density fluctuations. In Monte Carlo simulations of spatial stochastic predator-prey systems, one observes striking complex spatio-temporal structures. These spreading activity fronts induce persistent correlations between predators and prey. In the presence of local particle density restrictions (finite prey carrying capacity), there exists an extinction threshold for the predator population. The accompanying continuous non-equilibrium phase transition is governed by the directed-percolation universality class. We employ field-theoretic methods based on the Doi-Peliti representation of the master equation for stochastic particle interaction models to (i) map the ensuing action in the vicinity of the absorbing state phase transition to Reggeon field theory, and (ii) to quantitatively address fluctuation-induced renormalizations of the population oscillation frequency, damping, and diffusion coefficients in the species coexistence phase.

  11. Lionfish misidentification circumvents an optimized escape response by prey.

    Science.gov (United States)

    McCormick, Mark I; Allan, Bridie J M

    2016-01-01

    Invasive lionfish represent an unprecedented problem in the Caribbean basin, where they are causing major changes to foodwebs and habitats through their generalized predation on fishes and invertebrates. To ascertain what makes the red lionfish ( Pterois volitans ) such a formidable predator, we examined the reaction of a native damselfish prey, the whitetail damsel ( Pomacentrus chrysurus ), to a repeatable startle stimulus once they had been forewarned of the sight or smell of lionfish. Fast-start responses were compared with prey forewarned of a predatory rockcod ( Cephalopholis microprion ), a corallivorous butterflyfish ( Chaetodon trifasctiatus ) and experimental controls. Forewarning of the sight, smell or a combination of the two cues from a rockcod led to reduced escape latencies and higher response distances, speed and maximal speed compared with controls, suggesting that forewarning primed the prey and enabled a more effective escape response. In contrast, forewarning of lionfish did not affect the fast-start kinematics measured, which were the same as in the control and non-predatory butterflyfish treatments. Lionfish appear to be able to circumvent mechanisms commonly used by prey to identify predators and were misclassified as non-predatory, and this is likely to contribute to their success as predators.

  12. Testing for Camouflage Using Virtual Prey and Human "Predators"

    Science.gov (United States)

    Todd, Peter A.

    2009-01-01

    Camouflage is a prevalent feature of the natural world and as such has a ready appeal to students; however, it is a difficult subject to study using real predators and prey. This paper focuses how one fundamental type of camouflage, disruptive colouration (bold markings that break up the outline of the organism), can be tested using paper…

  13. The relative influence of prey abundance and co-breeders on the ...

    African Journals Online (AJOL)

    This study investigates if the reproductive performance of polyandrous Pale Chanting-goshawks, Melierax canorus, is governed by the abundance of dominant rodent-prey species or a co-breeding male participating fully in prey being delivered to the female and young. Polyandrous trios in prey-rich habitat, the only habitat ...

  14. Irreversible prey diapause as an optimal strategy of a physiologically extended Lotka-Volterra model

    NARCIS (Netherlands)

    Staňková, K.; Abate, A.; Sabelis, M.W.

    2013-01-01

    We propose an optimal control framework to describe intra-seasonal predator-prey interactions, which are characterized by a continuous-time dynamical model comprising predator and prey density, as well as the energy budget of the prey over the length of a season. The model includes a time-dependent

  15. Prey change behaviour with predation threat, but demographic effects vary with prey density: experiments with grasshoppers and birds.

    Science.gov (United States)

    Belovsky, Gary E; Laws, Angela Nardoni; Slade, Jennifer B

    2011-04-01

    Increasingly, ecologists emphasize that prey frequently change behaviour in the presence of predators and these behavioural changes can reduce prey survival and reproduction as much or more than predation itself. However, the effects of behavioural changes on survival and reproduction may vary with prey density due to intraspecific competition. In field experiments, we varied grasshopper density and threat of avian predation and measured grasshopper behaviour, survival and reproduction. Grasshopper behaviour changed with the threat of predation and these behavioural changes were invariant with grasshopper density. Behavioural changes with the threat of predation decreased per capita reproduction over all grasshopper densities; whereas the behavioural changes increased survival at low grasshopper densities and then decreased survival at high densities. At low grasshopper densities, the total reproductive output of the grasshopper population remained unchanged with predation threat, but declined at higher densities. The effects of behavioural changes with predation threat varied with grasshopper density because of a trade-off between survival and reproduction as intraspecific competition increased with density. Therefore, resource availability may need to be considered when assessing how prey behavioural changes with predation threat affect population and food web dynamics. © 2011 Blackwell Publishing Ltd/CNRS.

  16. Mechanical work as a determinant of prey-handling behavior in the tokay gecko (Gekko gecko).

    Science.gov (United States)

    Andrews, C; Bertram, J E

    1997-01-01

    In this study an in vitro analysis of the force and mechanical work required to bite prey items of different size and physical character is combined with an in vivo analysis of prey-handling behavior in the tokay gecko (Gekko gecko). The force required to bite and the work of biting increase with prey size, but the rate of increase is prey specific, with crickets (Acheta domestica) requiring substantially more force and work per bite than larvae (Galleria mellonella and Manduca sexta) for all but the smallest prey. Prey-handling behavior is also prey specific. Geckos exert more bites per feeding event on small crickets than on small insect larvae, but the number of bites increases faster with prey mass for larvae than for crickets. Combination of the in vitro mechanical measurements with the in vivo behavior analysis allows the calculation of total mechanical work per feeding event and indicates that total work increases with prey size but that the difference between prey types is far less than predicted from the differences in structural properties of the prey. This occurs because the number of bites and work per bite relationships tend to cancel the differences in the total work necessary to process each prey type. Thus, when considering the effect of prey size, a 13-fold greater rate of increase in bite force and an 18-fold greater rate of increase of work per bit for crickets over larvae was partially compensated for by a threefold increase in the number of bites used on larvae relative to crickets. These results can be interpreted in two ways. The effect of mechanical work in feeding behavior suggests that the energetics of jaw adductor musculature could play a greater role in governing the feeding behavior of this lizard than has previously been expected. Alternatively, the scaling of work in feeding over a range of prey sizes suggests distinct differences in the geometric features of the prey that determine how they are processed.

  17. The global stability of a delayed predator-prey system with two stage-structure

    International Nuclear Information System (INIS)

    Wang Fengyan; Pang Guoping

    2009-01-01

    Based on the classical delayed stage-structured model and Lotka-Volterra predator-prey model, we introduce and study a delayed predator-prey system, where prey and predator have two stages, an immature stage and a mature stage. The time delays are the time lengths between the immature's birth and maturity of prey and predator species. Results on global asymptotic stability of nonnegative equilibria of the delay system are given, which generalize and suggest that good continuity exists between the predator-prey system and its corresponding stage-structured system.

  18. Sabretoothed carnivores and the killing of large prey.

    Directory of Open Access Journals (Sweden)

    Ki Andersson

    Full Text Available Sabre-like canines clearly have the potential to inflict grievous wounds leading to massive blood loss and rapid death. Hypotheses concerning sabretooth killing modes include attack to soft parts such as the belly or throat, where biting deep is essential to generate strikes reaching major blood vessels. Sabretoothed carnivorans are widely interpreted as hunters of larger and more powerful prey than that of their present-day nonsabretoothed relatives. However, the precise functional advantage of the sabretooth bite, particularly in relation to prey size, is unknown. Here, we present a new point-to-point bite model and show that, for sabretooths, depth of the killing bite decreases dramatically with increasing prey size. The extended gape of sabretooths only results in considerable increase in bite depth when biting into prey with a radius of less than ∼10 cm. For sabretooths, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than "megaherbivores" as previously believed. The development of the sabretooth condition appears to represent a shift in function and killing behaviour, rather than one in predator-prey relations. Furthermore, our results demonstrate how sabretoothed carnivorans are likely to have evolved along a functionally continuous trajectory: beginning as an extension of a jaw-powered killing bite, as adopted by present-day pantherine cats, followed by neck-powered biting and thereafter shifting to neck-powered shear-biting. We anticipate this new insight to be a starting point for detailed study of the evolution of pathways that encompass extreme specialisation, for example, understanding how neck-powered biting shifts into shear-biting and its significance for predator-prey interactions. We also expect that our model for point-to-point biting and bite depth estimations will yield new insights into the behaviours of a broad range of

  19. Prey preferences of the snow leopard (Panthera uncia: regional diet specificity holds global significance for conservation.

    Directory of Open Access Journals (Sweden)

    Salvador Lyngdoh

    Full Text Available The endangered snow leopard is a large felid that is distributed over 1.83 million km(2 globally. Throughout its range it relies on a limited number of prey species in some of the most inhospitable landscapes on the planet where high rates of human persecution exist for both predator and prey. We reviewed 14 published and 11 unpublished studies pertaining to snow leopard diet throughout its range. We calculated prey consumption in terms of frequency of occurrence and biomass consumed based on 1696 analysed scats from throughout the snow leopard's range. Prey biomass consumed was calculated based on the Ackerman's linear correction factor. We identified four distinct physiographic and snow leopard prey type zones, using cluster analysis that had unique prey assemblages and had key prey characteristics which supported snow leopard occurrence there. Levin's index showed the snow leopard had a specialized dietary niche breadth. The main prey of the snow leopard were Siberian ibex (Capra sibrica, blue sheep (Pseudois nayaur, Himalayan tahr (Hemitragus jemlahicus, argali (Ovis ammon and marmots (Marmota spp. The significantly preferred prey species of snow leopard weighed 55±5 kg, while the preferred prey weight range of snow leopard was 36-76 kg with a significant preference for Siberian ibex and blue sheep. Our meta-analysis identified critical dietary resources for snow leopards throughout their distribution and illustrates the importance of understanding regional variation in species ecology; particularly prey species that have global implications for conservation.

  20. Prey preferences of the snow leopard (Panthera uncia): regional diet specificity holds global significance for conservation.

    Science.gov (United States)

    Lyngdoh, Salvador; Shrotriya, Shivam; Goyal, Surendra P; Clements, Hayley; Hayward, Matthew W; Habib, Bilal

    2014-01-01

    The endangered snow leopard is a large felid that is distributed over 1.83 million km(2) globally. Throughout its range it relies on a limited number of prey species in some of the most inhospitable landscapes on the planet where high rates of human persecution exist for both predator and prey. We reviewed 14 published and 11 unpublished studies pertaining to snow leopard diet throughout its range. We calculated prey consumption in terms of frequency of occurrence and biomass consumed based on 1696 analysed scats from throughout the snow leopard's range. Prey biomass consumed was calculated based on the Ackerman's linear correction factor. We identified four distinct physiographic and snow leopard prey type zones, using cluster analysis that had unique prey assemblages and had key prey characteristics which supported snow leopard occurrence there. Levin's index showed the snow leopard had a specialized dietary niche breadth. The main prey of the snow leopard were Siberian ibex (Capra sibrica), blue sheep (Pseudois nayaur), Himalayan tahr (Hemitragus jemlahicus), argali (Ovis ammon) and marmots (Marmota spp). The significantly preferred prey species of snow leopard weighed 55±5 kg, while the preferred prey weight range of snow leopard was 36-76 kg with a significant preference for Siberian ibex and blue sheep. Our meta-analysis identified critical dietary resources for snow leopards throughout their distribution and illustrates the importance of understanding regional variation in species ecology; particularly prey species that have global implications for conservation.

  1. Morphology of seahorse head hydrodynamically aids in capture of evasive prey.

    Science.gov (United States)

    Gemmell, Brad J; Sheng, Jian; Buskey, Edward J

    2013-01-01

    Syngnathid fish (seahorses, pipefish and sea dragons) are slow swimmers yet capture evasive prey (copepods) using a technique known as the 'pivot' feeding, which involves rapid movement to overcome prey escape capabilities. However, this feeding mode functions only at short range and requires approaching very closely to hydrodynamically sensitive prey without triggering an escape. Here we investigate the role of head morphology on prey capture using holographic and particle image velocimetry (PIV). We show that head morphology functions to create a reduced fluid deformation zone, minimizing hydrodynamic disturbance where feeding strikes occur (above the end of the snout), and permits syngnathid fish to approach highly sensitive copepod prey (Acartia tonsa) undetected. The results explain how these animals can successfully employ short range 'pivot' feeding effectively on evasive prey. The need to approach prey with stealth may have selected for a head shape that produces lower deformation rates than other fish.

  2. Small prey species' behaviour and welfare: implications for veterinary professionals.

    Science.gov (United States)

    McBride, E Anne

    2017-08-01

    People have obligations to ensure the welfare of animals under their care. Offences under the UK Animal Welfare Act are acts, or failures of action, causing unnecessary suffering. Veterinary professionals need to be able to provide current, scientifically based prophylactic advice, and respect the limits of their expertise. The ethical concept of a life worth living and the Five Freedoms are core to welfare. Behaviour is a central component, both influencing and influenced by physical health. Owners frequently misunderstand the behaviour of small prey mammals and how to meet their needs. This review provides insight into the physical-social (external) and the cognitive-emotional (internal) environments of small prey mammals, contextualised within an evolutionary perspective. This is extrapolated to captivity and practical suggestions given for meeting behavioural freedoms and enhancing client understanding and enjoyment of their animals, thereby improving welfare. © 2017 British Small Animal Veterinary Association.

  3. Environmental versus demographic variability in stochastic predator–prey models

    International Nuclear Information System (INIS)

    Dobramysl, U; Täuber, U C

    2013-01-01

    In contrast to the neutral population cycles of the deterministic mean-field Lotka–Volterra rate equations, including spatial structure and stochastic noise in models for predator–prey interactions yields complex spatio-temporal structures associated with long-lived erratic population oscillations. Environmental variability in the form of quenched spatial randomness in the predation rates results in more localized activity patches. Our previous study showed that population fluctuations in rare favorable regions in turn cause a remarkable increase in the asymptotic densities of both predators and prey. Very intriguing features are found when variable interaction rates are affixed to individual particles rather than lattice sites. Stochastic dynamics with demographic variability in conjunction with inheritable predation efficiencies generate non-trivial time evolution for the predation rate distributions, yet with overall essentially neutral optimization. (paper)

  4. Bifurcation Behavior Analysis in a Predator-Prey Model

    Directory of Open Access Journals (Sweden)

    Nan Wang

    2016-01-01

    Full Text Available A predator-prey model is studied mathematically and numerically. The aim is to explore how some key factors influence dynamic evolutionary mechanism of steady conversion and bifurcation behavior in predator-prey model. The theoretical works have been pursuing the investigation of the existence and stability of the equilibria, as well as the occurrence of bifurcation behaviors (transcritical bifurcation, saddle-node bifurcation, and Hopf bifurcation, which can deduce a standard parameter controlled relationship and in turn provide a theoretical basis for the numerical simulation. Numerical analysis ensures reliability of the theoretical results and illustrates that three stable equilibria will arise simultaneously in the model. It testifies the existence of Bogdanov-Takens bifurcation, too. It should also be stressed that the dynamic evolutionary mechanism of steady conversion and bifurcation behavior mainly depend on a specific key parameter. In a word, all these results are expected to be of use in the study of the dynamic complexity of ecosystems.

  5. Vertebrate predator-prey interactions in a seasonal environment

    DEFF Research Database (Denmark)

    Schmidt, Niels Martin; Berg, Thomas B; Forchhammer, Mads

    2008-01-01

    erminea predation and stabilising predation from the generalist predators, in Zackenbergdalen mainly the arctic fox Alopex lagopus. In Zackenbergdalen, however, the coupling between the specialist stoat and the lemming population is relatively weak. During summer, the predation pressure is high......The High Arctic, with its low number of species, is characterised by a relatively simple ecosystem, and the vertebrate predator-prey interactions in the valley Zackenbergdalen in Northeast Greenland are centred around the collared lemming Dicrostonyx groenlandicus and its multiple predators...

  6. The Neuronal Control of Flying Prey Interception in Dragonflies

    Science.gov (United States)

    2014-08-19

    Gonzalez-Bellido’s fluorescent dye ( Lucifer -yellow) injections illuminated for the first time the anatomy of the output regions of the TSDNs...out in Cape Cod (MA) to test the effect of bead size(C), and in the Olberg Laboratory (Union College, NY) to test the effect of bead speed by...AFRL-OSR-VA-TR-2014-0193 THE NEURONAL CONTROL OF FLYING PREY INTERCEPTION IN DRAGONFLIES Robert Olberg TRUSTEES OF UNION COLLEGE IN THE TOWN OF

  7. Prey selection of Tawny owls (Strix aluco) on Yellow necked mouse and Bank Vole

    DEFF Research Database (Denmark)

    Forsom, H. M.; Sunde, P.; Overskaug, K.

    As predators owls may have a strong impact on mortality of their favourite prey, and may therefore act as important selective agents on their prey species. Little is known, however, about whether owls choose prey randomly or if some prey items suffer a higher risk of predation due to certain life...

  8. Mountain lions prey selectively on prion-infected mule deer

    Science.gov (United States)

    Krumm, Caroline E.; Conner, Mary M.; Hobbs, N. Thompson; Hunter, Don O.; Miller, Michael W.

    2010-01-01

    The possibility that predators choose prey selectively based on age or condition has been suggested but rarely tested. We examined whether mountain lions (Puma concolor) selectively prey upon mule deer (Odocoileus hemionus) infected with chronic wasting disease, a prion disease. We located kill sites of mountain lions in the northern Front Range of Colorado, USA, and compared disease prevalence among lion-killed adult (≥2 years old) deer with prevalence among sympatric deer taken by hunters in the vicinity of kill sites. Hunter-killed female deer were less likely to be infected than males (odds ratios (OR) = 0.2, 95% confidence intervals (CI) = 0.1–0.6; p = 0.015). However, both female (OR = 8.5, 95% CI = 2.3–30.9) and male deer (OR = 3.2, 95% CI = 1–10) killed by a mountain lion were more likely to be infected than same-sex deer killed in the vicinity by a hunter (p < 0.001), suggesting that mountain lions in this area actively selected prion-infected individuals when targeting adult mule deer as prey items. PMID:19864271

  9. Predator size and the suitability of a common prey.

    Science.gov (United States)

    Erickson, Kristin S; Morse, D H

    1997-02-01

     Although a predator's mass should influence the suitability of its prey, this subject has received little direct attention. We studied the capture and processing of an abundant syrphid fly Toxomerus marginatus (c. 4 mg) by 0.6- to 40-mg juvenile crab spiders Misumena vatia (Thomisidae) to determine how profitability, relative profitability (profitability/predator mass), overall gain in mass, and relative gain in mass differed with predator mass, and whether foraging changed concurrently. In multi-prey experiments, the smallest successful spiders (0.6-3.0 mg) extracted less mass from flies, and did so more slowly, than large spiders. This gain was proportionately similar to that of 10- to 40-mg spiders with access to many Toxomerus. However, many small spiders failed to capture flies. When we gave spiders only a single Toxomerus, the smallest ones again extracted mass more slowly than the large ones and increased in mass less than the large ones, but increased in mass proportionately more than large ones. Relative gain in mass from a single prey decreased with increasing spider mass. Spiders larger than 10 mg all extracted similar amounts of mass from a single Toxomerus at similar rates, but varied in time spent between captures. Thus, Toxomerus changes with spider mass from a large, hard-to-capture bonanza to a small, easy-to-capture item of low per capita value. However, Toxomerus is common enough that large spiders can capture it en masse, thereby compensating for its decline in per capita value.

  10. Brominated flame retardants in birds of prey from Flanders, Belgium

    Energy Technology Data Exchange (ETDEWEB)

    Voorspoels, S.; Covaci, A.; Schepens, P. [Antwerp Univ., Wilrijk (Belgium). Toxicological Centre

    2004-09-15

    Since their introduction on the market, environmental levels of polybrominated diphenyl ethers (PBDEs) are continuously increasing. This is caused by spillage and emission during production and use, but also by improper disposal at the end-of-life of the products in which they are used. These chemicals are highly persistent and lipophilic which results in bioaccumulation in fatty tissues of biota and biomagnification throughout the food chain. Because PBDEs have a high toxicological potential, this biomagnification can have serious health consequences for top-predators, such as birds of prey. Data about PBDE concentrations in terrestrial biota, especially in birds of prey, is scarce. A rapid increase of PBDE concentrations has been seen in pooled guillemot (Uria algae) eggs from the Baltic proper7 during the late 1970's and early 1980's, followed by a decrease during the 1990's8. In herring gull eggs from the Great Lakes, the PBDE concentrations increased exponentially from 1981 to 2000. Most of the studies look at concentrations in eggs, while less is known about tissue levels and distribution of these pollutants in birds of prey.

  11. Noise-induced extinction for a ratio-dependent predator-prey model with strong Allee effect in prey

    Science.gov (United States)

    Mandal, Partha Sarathi

    2018-04-01

    In this paper, we study a stochastically forced ratio-dependent predator-prey model with strong Allee effect in prey population. In the deterministic case, we show that the model exhibits the stable interior equilibrium point or limit cycle corresponding to the co-existence of both species. We investigate a probabilistic mechanism of the noise-induced extinction in a zone of stable interior equilibrium point. Computational methods based on the stochastic sensitivity function technique are applied for the analysis of the dispersion of random states near stable interior equilibrium point. This method allows to construct a confidence domain and estimate the threshold value of the noise intensity for a transition from the coexistence to the extinction.

  12. Red trap colour of the carnivorous plant Drosera rotundifolia does not serve a prey attraction or camouflage function.

    Science.gov (United States)

    Foot, G; Rice, S P; Millett, J

    2014-01-01

    The traps of many carnivorous plants are red in colour. This has been widely hypothesized to serve a prey attraction function; colour has also been hypothesized to function as camouflage, preventing prey avoidance. We tested these two hypotheses in situ for the carnivorous plant Drosera rotundifolia. We conducted three separate studies: (i) prey attraction to artificial traps to isolate the influence of colour; (ii) prey attraction to artificial traps on artificial backgrounds to control the degree of contrast and (iii) observation of prey capture by D. rotundifolia to determine the effects of colour on prey capture. Prey were not attracted to green traps and were deterred from red traps. There was no evidence that camouflaged traps caught more prey. For D. rotundifolia, there was a relationship between trap colour and prey capture. However, trap colour may be confounded with other leaf traits. Thus, we conclude that for D. rotundifolia, red trap colour does not serve a prey attraction or camouflage function.

  13. Occurrence of enteropathogenic bacteria in birds of prey in Italy.

    Science.gov (United States)

    Gargiulo, A; Fioretti, A; Russo, T P; Varriale, L; Rampa, L; Paone, S; De Luca Bossa, L M; Raia, P; Dipineto, L

    2018-03-01

    The importance of wild birds as potential vectors of disease has received recent renewed empirical interest, especially regarding human health although information regarding the enteropathogenic bacteria in birds of prey continue to be scant. This study was performed with the aim to evaluate the occurrence of enteropathogenic bacteria (i.e. Campylobacter spp. Escherichia coli, Salmonella spp.) in birds of prey carcasses in Southern Italy. The results of the present study showed a prevalence of 33·1% (49/148) for Campylobacter spp. where all positive isolates (49/49) were identified as Campylobacter jejuni, and among these positive 12/49 were also identified as Campylobacter coli. Thus, 12/49 birds of prey showed mixed infections for both Campylobacter species. Differences in Campylobacter spp. prevalence between diurnal and nocturnal birds were statistically significant (P = 0·016). Escherichia coli showed a prevalence of 6·8% (10/148) and were serogrouped as O26 (n = 3), O55 (n = 2), O145 (n = 5). Salmonella spp. showed a prevalence of 6·8% (10/148) and were serotyped as S. Napoli (n = 4), Salmonella salamae (n = 3) and S. Typhimurium (n = 3). Although wildlife disease outbreaks have often been underreported in the broader context of global epidemiology, results of the present study suggest that birds of prey may serve as a reservoir of pathogens for livestock and human health, acting at the animal-human-ecosystem interface. This study confirms the role of birds of prey as a reservoir of enteropathogenic bacteria (i.e. Campylobacter spp., Escherichia coli, Salmonella spp.). Wild birds can contaminate environment with their faeces and play a crucial role in the transmission of pathogens to poultry and livestock farms and aquifers supplying water to humans. Furthermore, wild birds could disseminate pathogens within rescue and rehabilitation centres where they are admitted. © 2017 The Society for Applied Microbiology.

  14. Weather and Prey Predict Mammals' Visitation to Water.

    Directory of Open Access Journals (Sweden)

    Grant Harris

    Full Text Available Throughout many arid lands of Africa, Australia and the United States, wildlife agencies provide water year-round for increasing game populations and enhancing biodiversity, despite concerns that water provisioning may favor species more dependent on water, increase predation, and reduce biodiversity. In part, understanding the effects of water provisioning requires identifying why and when animals visit water. Employing this information, by matching water provisioning with use by target species, could assist wildlife management objectives while mitigating unintended consequences of year-round watering regimes. Therefore, we examined if weather variables (maximum temperature, relative humidity [RH], vapor pressure deficit [VPD], long and short-term precipitation and predator-prey relationships (i.e., prey presence predicted water visitation by 9 mammals. We modeled visitation as recorded by trail cameras at Sevilleta National Wildlife Refuge, New Mexico, USA (June 2009 to September 2014 using generalized linear modeling. For 3 native ungulates, elk (Cervus Canadensis, mule deer (Odocoileus hemionus, and pronghorn (Antilocapra americana, less long-term precipitation and higher maximum temperatures increased visitation, including RH for mule deer. Less long-term precipitation and higher VPD increased oryx (Oryx gazella and desert cottontail rabbits (Sylvilagus audubonii visitation. Long-term precipitation, with RH or VPD, predicted visitation for black-tailed jackrabbits (Lepus californicus. Standardized model coefficients demonstrated that the amount of long-term precipitation influenced herbivore visitation most. Weather (especially maximum temperature and prey (cottontails and jackrabbits predicted bobcat (Lynx rufus visitation. Mule deer visitation had the largest influence on coyote (Canis latrans visitation. Puma (Puma concolor visitation was solely predicted by prey visitation (elk, mule deer, oryx. Most ungulate visitation peaked during

  15. Weather and Prey Predict Mammals’ Visitation to Water

    Science.gov (United States)

    Harris, Grant; Sanderson, James G.; Erz, Jon; Lehnen, Sarah E.; Butler, Matthew J.

    2015-01-01

    Throughout many arid lands of Africa, Australia and the United States, wildlife agencies provide water year-round for increasing game populations and enhancing biodiversity, despite concerns that water provisioning may favor species more dependent on water, increase predation, and reduce biodiversity. In part, understanding the effects of water provisioning requires identifying why and when animals visit water. Employing this information, by matching water provisioning with use by target species, could assist wildlife management objectives while mitigating unintended consequences of year-round watering regimes. Therefore, we examined if weather variables (maximum temperature, relative humidity [RH], vapor pressure deficit [VPD], long and short-term precipitation) and predator-prey relationships (i.e., prey presence) predicted water visitation by 9 mammals. We modeled visitation as recorded by trail cameras at Sevilleta National Wildlife Refuge, New Mexico, USA (June 2009 to September 2014) using generalized linear modeling. For 3 native ungulates, elk (Cervus Canadensis), mule deer (Odocoileus hemionus), and pronghorn (Antilocapra americana), less long-term precipitation and higher maximum temperatures increased visitation, including RH for mule deer. Less long-term precipitation and higher VPD increased oryx (Oryx gazella) and desert cottontail rabbits (Sylvilagus audubonii) visitation. Long-term precipitation, with RH or VPD, predicted visitation for black-tailed jackrabbits (Lepus californicus). Standardized model coefficients demonstrated that the amount of long-term precipitation influenced herbivore visitation most. Weather (especially maximum temperature) and prey (cottontails and jackrabbits) predicted bobcat (Lynx rufus) visitation. Mule deer visitation had the largest influence on coyote (Canis latrans) visitation. Puma (Puma concolor) visitation was solely predicted by prey visitation (elk, mule deer, oryx). Most ungulate visitation peaked during May and

  16. Bottom trawl assessment of Lake Ontario prey fishes

    Science.gov (United States)

    Weidel, Brian C.; Connerton, Michael J.; Holden, Jeremy

    2018-01-01

    Managing Lake Ontario fisheries in an ecosystem-context requires prey fish community and population data. Since 1978, multiple annual bottom trawl surveys have quantified prey fish dynamics to inform management relative to published Fish Community Objectives. In 2017, two whole-lake surveys collected 341 bottom trawls (spring: 204, fall: 137), at depths from 8-225m, and captured 751,350 fish from 29 species. Alewife were 90% of the total fish catch while Deepwater Sculpin, Round Goby, and Rainbow Smelt comprised the majority of the remaining total catch (3.8, 3.1, and 1.1% respectively). The adult Alewife abundance index for US waters increased in 2017 relative to 2016, however the index for Canadian waters declined. Adult Alewife condition, assessed by the predicted weight of a 165 mm fish (6.5 inches), declined in 2017 from record high values observed in spring 2016. Spring 2017 Alewife condition was slightly less than the 10-year average, but the fall value was well below the 10-year average, likely due to increased Age-1 Alewife abundance. The Age-1 Alewife abundance index was the highest observed in 40 years, and 8-times higher than the previous year. The Age-1 index estimates Alewife reproductive success the preceding year. The warm summer and winter of 2016 likely contributed to the large year class. In contrast the relatively cool 2017 spring and cold winter may result in a lower than average 2017 year class. Abundance indices for Rainbow Smelt, Cisco, and Emerald Shiner either declined or remained at low levels in 2017. Pelagic prey fish diversity continues to be low since a single species, Alewife, dominates the catch. Deepwater Sculpin were the most abundant benthic prey fish in 2017 because Round Goby abundance declined sharply from 2016. Slimy Sculpin density continued to decline and the 2017 biomass index for US waters was the lowest ever observed. Prior to Round Goby proliferation, juvenile Slimy Sculpin comprised ~10% of the Slimy Sculpin catch, but

  17. Always chew your food: freshwater stingrays use mastication to process tough insect prey.

    Science.gov (United States)

    Kolmann, Matthew A; Welch, Kenneth C; Summers, Adam P; Lovejoy, Nathan R

    2016-09-14

    Chewing, characterized by shearing jaw motions and high-crowned molar teeth, is considered an evolutionary innovation that spurred dietary diversification and evolutionary radiation of mammals. Complex prey-processing behaviours have been thought to be lacking in fishes and other vertebrates, despite the fact that many of these animals feed on tough prey, like insects or even grasses. We investigated prey capture and processing in the insect-feeding freshwater stingray Potamotrygon motoro using high-speed videography. We find that Potamotrygon motoro uses asymmetrical motion of the jaws, effectively chewing, to dismantle insect prey. However, CT scanning suggests that this species has simple teeth. These findings suggest that in contrast to mammalian chewing, asymmetrical jaw action is sufficient for mastication in other vertebrates. We also determined that prey capture in these rays occurs through rapid uplift of the pectoral fins, sucking prey beneath the ray's body, thereby dissociating the jaws from a prey capture role. We suggest that the decoupling of prey capture and processing facilitated the evolution of a highly kinetic feeding apparatus in batoid fishes, giving these animals an ability to consume a wide variety of prey, including molluscs, fishes, aquatic insect larvae and crustaceans. We propose Potamotrygon as a model system for understanding evolutionary convergence of prey processing and chewing in vertebrates. © 2016 The Author(s).

  18. What you need is what you eat? Prey selection by the bat Myotis daubentonii.

    Science.gov (United States)

    Vesterinen, Eero J; Ruokolainen, Lasse; Wahlberg, Niklas; Peña, Carlos; Roslin, Tomas; Laine, Veronika N; Vasko, Ville; Sääksjärvi, Ilari E; Norrdahl, Kai; Lilley, Thomas M

    2016-04-01

    Optimal foraging theory predicts that predators are selective when faced with abundant prey, but become less picky when prey gets sparse. Insectivorous bats in temperate regions are faced with the challenge of building up fat reserves vital for hibernation during a period of decreasing arthropod abundances. According to optimal foraging theory, prehibernating bats should adopt a less selective feeding behavior--yet empirical studies have revealed many apparently generalized species to be composed of specialist individuals. Targeting the diet of the bat Myotis daubentonii, we used a combination of molecular techniques to test for seasonal changes in prey selectivity and individual-level variation in prey preferences. DNA metabarcoding was used to characterize both the prey contents of bat droppings and the insect community available as prey. To test for dietary differences among M. daubentonii individuals, we used ten microsatellite loci to assign droppings to individual bats. The comparison between consumed and available prey revealed a preference for certain prey items regardless of availability. Nonbiting midges (Chironomidae) remained the most highly consumed prey at all times, despite a significant increase in the availability of black flies (Simuliidae) towards the end of the season. The bats sampled showed no evidence of individual specialization in dietary preferences. Overall, our approach offers little support for optimal foraging theory. Thus, it shows how novel combinations of genetic markers can be used to test general theory, targeting patterns at both the level of prey communities and individual predators. © 2016 John Wiley & Sons Ltd.

  19. Benefits of Group Foraging Depend on Prey Type in a Small Marine Predator, the Little Penguin.

    Science.gov (United States)

    Sutton, Grace J; Hoskins, Andrew J; Arnould, John P Y

    2015-01-01

    Group foraging provides predators with advantages in over-powering prey larger than themselves or in aggregating small prey for efficient exploitation. For group-living predatory species, cooperative hunting strategies provide inclusive fitness benefits. However, for colonial-breeding predators, the benefit pay-offs of group foraging are less clear due to the potential for intra-specific competition. We used animal-borne cameras to determine the prey types, hunting strategies, and success of little penguins (Eudyptula minor), a small, colonial breeding air-breathing marine predator that has recently been shown to display extensive at-sea foraging associations with conspecifics. Regardless of prey type, little penguins had a higher probability of associating with conspecifics when hunting prey that were aggregated than when prey were solitary. In addition, success was greater when individuals hunted schooling rather than solitary prey. Surprisingly, however, success on schooling prey was similar or greater when individuals hunted on their own than when with conspecifics. These findings suggest individuals may be trading-off the energetic gains of solitary hunting for an increased probability of detecting prey within a spatially and temporally variable prey field by associating with conspecifics.

  20. Prey selection by Bengal Tiger Panthera tigris tigris (Mammalia: Carnivora: Felidae of Chitwan National Park, Nepal

    Directory of Open Access Journals (Sweden)

    Saneer Lamichhane

    2015-11-01

    Full Text Available Prey selection by tiger in Chitwan National Park, Nepal was studied from 77 tiger scats that contained the remains of principal prey species.  The scats were collected from January to March 2010.  Government reports on herbivore population in Chitwan provided the base data on density of principal prey species.  In order to understand prey selectivity, the observed proportion of prey species in the scats were compared with the expected proportion derived from density estimates.  The observed scat frequency of Sambar, Hog Deer and Wild Boar was found to be greater than the estimated frequency, and the reverse was true for Chital and Muntjac.  The average weight of the principal prey species killed was 84 kg. According to our results, Chital and Sambar constituted the bulk (82.07%, and Hog Deer, Wild Boar, and Muntjac constituted 17.93% of the tiger diet.  Sambar contributed the largest bulk (43.75% of prey composition, but Chital constituted the relatively most killed (50.36% prey species.  The present study makes a contribution to an understanding of the status of prey composition in tiger scat in Chitwan during the year 2010.  The study also highlights that both large and medium sized prey are important for the conservation of tiger in Chitwan National Park. 

  1. A specialized araneophagic predator's short-term nutrient utilization depends on the macronutrient content of prey rather than on prey taxonomic affiliation

    DEFF Research Database (Denmark)

    Toft, Søren; Li, Daiqin; Mayntz, David

    2010-01-01

    rate of high-protein flies than of high-lipid flies and spiders but, after 5 days of feeding, there is no significant difference in growth between treatments, and the diets lead to significant changes in the macronutrient composition of P. quei as a result of variable extraction and utilization...... of the prey. The short-term utilization of spider prey is similar to that of high-lipid flies and both differ in several respects from the utilization of high-protein flies. Thus, the short-term nutrient utilization is better explained by prey macronutrient content than by whether the prey is a spider or not....... The results suggest that spider prey may have a more optimal macronutrient composition for P. quei and that P. quei does not depend on spider-specific substances....

  2. Nitrogen deposition and prey nitrogen uptake control the nutrition of the carnivorous plant Drosera rotundifolia

    Energy Technology Data Exchange (ETDEWEB)

    Millett, J., E-mail: j.millett@lboro.ac.uk [Centre for Hydrological and Ecosystem Science, Department of Geography, Loughborough University, Loughborough LE11 3TU (United Kingdom); Foot, G.W. [Centre for Hydrological and Ecosystem Science, Department of Geography, Loughborough University, Loughborough LE11 3TU (United Kingdom); Svensson, B.M. [Department of Plant Ecology and Evolution, Uppsala University, Norbyvägen 18 D, SE-752 36 Uppsala (Sweden)

    2015-04-15

    Nitrogen (N) deposition has important negative impacts on natural and semi-natural ecosystems, impacting on biotic interactions across trophic levels. Low-nutrient systems are particularly sensitive to changes in N inputs and are therefore more vulnerable to N deposition. Carnivorous plants are often part of these ecosystems partly because of the additional nutrients obtained from prey. We studied the impact of N deposition on the nutrition of the carnivorous plant Drosera rotundifolia growing on 16 ombrotrophic bogs across Europe. We measured tissue N, phosphorus (P) and potassium (K) concentrations and prey and root N uptake using a natural abundance stable isotope approach. Our aim was to test the impact of N deposition on D. rotundifolia prey and root N uptake, and nutrient stoichiometry. D. rotundifolia root N uptake was strongly affected by N deposition, possibly resulting in reduced N limitation. The contribution of prey N to the N contained in D. rotundifolia ranged from 20 to 60%. N deposition reduced the maximum amount of N derived from prey, but this varied below this maximum. D. rotundifolia tissue N concentrations were a product of both root N availability and prey N uptake. Increased prey N uptake was correlated with increased tissue P concentrations indicating uptake of P from prey. N deposition therefore reduced the strength of a carnivorous plant–prey interaction, resulting in a reduction in nutrient transfer between trophic levels. We suggest that N deposition has a negative impact on D. rotundifolia and that responses to N deposition might be strongly site specific. - Highlights: • We measured nutrition of the carnivorous plant Drosera rotundifolia across Europe. • We measured tissue nutrient concentrations and prey and root N uptake at 16 sites. • Tissue N concentrations were a product of root N availability and prey N uptake. • N deposition reduced the maximum amount of N derived from prey. • N deposition reduced the strength of a

  3. Nitrogen deposition and prey nitrogen uptake control the nutrition of the carnivorous plant Drosera rotundifolia

    International Nuclear Information System (INIS)

    Millett, J.; Foot, G.W.; Svensson, B.M.

    2015-01-01

    Nitrogen (N) deposition has important negative impacts on natural and semi-natural ecosystems, impacting on biotic interactions across trophic levels. Low-nutrient systems are particularly sensitive to changes in N inputs and are therefore more vulnerable to N deposition. Carnivorous plants are often part of these ecosystems partly because of the additional nutrients obtained from prey. We studied the impact of N deposition on the nutrition of the carnivorous plant Drosera rotundifolia growing on 16 ombrotrophic bogs across Europe. We measured tissue N, phosphorus (P) and potassium (K) concentrations and prey and root N uptake using a natural abundance stable isotope approach. Our aim was to test the impact of N deposition on D. rotundifolia prey and root N uptake, and nutrient stoichiometry. D. rotundifolia root N uptake was strongly affected by N deposition, possibly resulting in reduced N limitation. The contribution of prey N to the N contained in D. rotundifolia ranged from 20 to 60%. N deposition reduced the maximum amount of N derived from prey, but this varied below this maximum. D. rotundifolia tissue N concentrations were a product of both root N availability and prey N uptake. Increased prey N uptake was correlated with increased tissue P concentrations indicating uptake of P from prey. N deposition therefore reduced the strength of a carnivorous plant–prey interaction, resulting in a reduction in nutrient transfer between trophic levels. We suggest that N deposition has a negative impact on D. rotundifolia and that responses to N deposition might be strongly site specific. - Highlights: • We measured nutrition of the carnivorous plant Drosera rotundifolia across Europe. • We measured tissue nutrient concentrations and prey and root N uptake at 16 sites. • Tissue N concentrations were a product of root N availability and prey N uptake. • N deposition reduced the maximum amount of N derived from prey. • N deposition reduced the strength of a

  4. Seasonal foraging ecology of non-migratory cougars in a system with migrating prey.

    Directory of Open Access Journals (Sweden)

    L Mark Elbroch

    Full Text Available We tested for seasonal differences in cougar (Puma concolor foraging behaviors in the Southern Yellowstone Ecosystem, a multi-prey system in which ungulate prey migrate, and cougars do not. We recorded 411 winter prey and 239 summer prey killed by 28 female and 10 male cougars, and an additional 37 prey items by unmarked cougars. Deer composed 42.4% of summer cougar diets but only 7.2% of winter diets. Males and females, however, selected different proportions of different prey; male cougars selected more elk (Cervus elaphus and moose (Alces alces than females, while females killed greater proportions of bighorn sheep (Ovis canadensis, pronghorn (Antilocapra americana, mule deer (Odocoileus hemionus and small prey than males. Kill rates did not vary by season or between males and females. In winter, cougars were more likely to kill prey on the landscape as: 1 elevation decreased, 2 distance to edge habitat decreased, 3 distance to large bodies of water decreased, and 4 steepness increased, whereas in summer, cougars were more likely to kill in areas as: 1 elevation decreased, 2 distance to edge habitat decreased, and 3 distance from large bodies of water increased. Our work highlighted that seasonal prey selection exhibited by stationary carnivores in systems with migratory prey is not only driven by changing prey vulnerability, but also by changing prey abundances. Elk and deer migrations may also be sustaining stationary cougar populations and creating apparent competition scenarios that result in higher predation rates on migratory bighorn sheep in winter and pronghorn in summer. Nevertheless, cougar predation on rare ungulates also appeared to be influenced by individual prey selection.

  5. Intensity and directionality of bat echolocation signals

    DEFF Research Database (Denmark)

    Jakobsen, Lasse; Brinkløv, Signe; Surlykke, Annemarie

    2013-01-01

    will increase signal directionality in the field along with intensity thus increasing sonar range. During the last phase of prey pursuit, vespertilionid bats broaden their echolocation beam considerably, probably to counter evasive maneuvers of eared prey. We highlight how multiple call parameters (frequency......The paper reviews current knowledge of intensity and directionality of bat echolocation signals. Recent studies have revealed that echolocating bats can be much louder than previously believed. Bats previously dubbed "whispering" can emit calls with source levels up to 110 dB SPL at 10 cm......, duration, intensity, and directionality of echolocation signals) in unison define the search volume probed by bats and in turn how bats perceive their surroundings. Small changes to individual parameters can, in combination, drastically change the bat's perception, facilitating successful navigation...

  6. Availability and abundance of prey for the red-cockaded woodpecker.

    Energy Technology Data Exchange (ETDEWEB)

    Hanula, James, L.; Horn, Scott

    2004-12-31

    Red-cockaded woodpecker; Road to Recovery. Proceedings of the 4th Red-cockaded woodpecker Symposium. Ralph Costa and Susan J. Daniels, eds. Savannah, Georgia. January, 2003. Chapter 11. Prey, Fire, and Community Ecology. Pp 633-645. Abstract: Over a 10-year period we investigated red-cockaded woodpecker (Picoides borealis) prey use, sources of prey, prey distribution within trees and stands, and how forest management decisions affect prey abundance in South Carolina, Alabama, Georgia and Florida. Cameras were operated at 31 nest cavities to record nest visits with prey in 4 locations that ranged in foraging habitat from pine stands established in old fields to an old-growth stand in South Georgia. Examination of nearly 12,000 photographs recorded over 5 years revealed that, although red-cockaded woodpeckers used over 40 arthropods for food, the majority of the nestling diet is comprised of a relatively small number of common arthropods.

  7. Foraging mode and prey size spectra of suspension-feeding copepods and other zooplankton

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2016-01-01

    Prey size spectra of suspension-feeding zooplankton may be predicted from foraging mode and a mechanistic understanding of prey perception and capture. I examine this for suspension-feeding copepods where 2 foraging modes can be distinguished: ambush feeding and active (i.e. cruising and feeding-...... the prediction. I also make qualitative predictions of food size spectra in zooplankton with other prey perception mechanisms that accord with observations....

  8. Prey preference follows phylogeny: evolutionary dietary patterns within the marine gastropod group Cladobranchia (Gastropoda: Heterobranchia: Nudibranchia).

    Science.gov (United States)

    Goodheart, Jessica A; Bazinet, Adam L; Valdés, Ángel; Collins, Allen G; Cummings, Michael P

    2017-10-26

    The impact of predator-prey interactions on the evolution of many marine invertebrates is poorly understood. Since barriers to genetic exchange are less obvious in the marine realm than in terrestrial or freshwater systems, non-allopatric divergence may play a fundamental role in the generation of biodiversity. In this context, shifts between major prey types could constitute important factors explaining the biodiversity of marine taxa, particularly in groups with highly specialized diets. However, the scarcity of marine specialized consumers for which reliable phylogenies exist hampers attempts to test the role of trophic specialization in evolution. In this study, RNA-Seq data is used to produce a phylogeny of Cladobranchia, a group of marine invertebrates that feed on a diverse array of prey taxa but mostly specialize on cnidarians. The broad range of prey type preferences allegedly present in two major groups within Cladobranchia suggest that prey type shifts are relatively common over evolutionary timescales. In the present study, we generated a well-supported phylogeny of the major lineages within Cladobranchia using RNA-Seq data, and used ancestral state reconstruction analyses to better understand the evolution of prey preference. These analyses answered several fundamental questions regarding the evolutionary relationships within Cladobranchia, including support for a clade of species from Arminidae as sister to Tritoniidae (which both preferentially prey on Octocorallia). Ancestral state reconstruction analyses supported a cladobranchian ancestor with a preference for Hydrozoa and show that the few transitions identified only occur from lineages that prey on Hydrozoa to those that feed on other types of prey. There is strong phylogenetic correlation with prey preference within Cladobranchia, suggesting that prey type specialization within this group has inertia. Shifts between different types of prey have occurred rarely throughout the evolution of

  9. Stomach fullness shapes prey choice decisions in crab plovers (Dromas ardeola)

    Science.gov (United States)

    Bom, Roeland A.; Fijen, Thijs P. M.; van Gils, Jan A.

    2018-01-01

    Foragers whose energy intake rate is constrained by search and handling time should, according to the contingency model (CM), select prey items whose profitability exceeds or equals the forager’s long-term average energy intake rate. This rule does not apply when prey items are found and ingested at a higher rate than the digestive system can process them. According to the digestive rate model (DRM), foragers in such situations should prefer prey with the highest digestive quality, instead of the highest profitability. As the digestive system fills up, the limiting constraint switches from ingestion rate to digestion rate, and prey choice is expected to change accordingly for foragers making decisions over a relative short time window. We use these models to understand prey choice in crab plovers (Dromas ardeola), preying on either small burrowing crabs that are swallowed whole (high profitability, but potentially inducing a digestive constraint) or on larger swimming crabs that are opened to consume only the flesh (low profitability, but easier to digest). To parameterize the CM and DRM, we measured energy content, ballast mass and handling times for different sized prey, and the birds’ digestive capacity in three captive individuals. Subsequently, these birds were used in ad libitum experiments to test if they obeyed the rules of the CM or DRM. We found that crab plovers with an empty stomach mainly chose the most profitable prey, matching the CM. When stomach fullness increased, the birds switched their preference from the most profitable prey to the highest-quality prey, matching the predictions of the DRM. This shows that prey choice is context dependent, affected by the stomach fullness of an animal. Our results suggest that prey choice experiments should be carefully interpreted, especially under captive conditions as foragers often ‘fill up’ in the course of feeding trials. PMID:29641542

  10. Do top predators cue on sound production by mesopelagic prey?

    Science.gov (United States)

    Baumann-Pickering, S.; Checkley, D. M., Jr.; Demer, D. A.

    2016-02-01

    Deep-scattering layer (DSL) organisms, comprising a variety of mesopelagic fishes, and squids, siphonophores, crustaceans, and other invertebrates, are preferred prey for numerous large marine predators, e.g. cetaceans, seabirds, and fishes. Some of the DSL species migrate from depth during daylight to feed near the surface at night, transitioning during dusk and dawn. We investigated if any DSL organisms create sound, particularly during the crepuscular periods. Over several nights in summer 2015, underwater sound was recorded in the San Diego Trough using a high-frequency acoustic recording package (HARP, 10 Hz to 100 kHz), suspended from a drifting surface float. Acoustic backscatter from the DSL was monitored nearby using a calibrated multiple-frequency (38, 70, 120, and 200 kHz) split-beam echosounder (Simrad EK60) on a small boat. DSL organisms produced sound, between 300 and 1000 Hz, and the received levels were highest when the animals migrated past the recorder during ascent and descent. The DSL are globally present, so the observed acoustic phenomenon, if also ubiquitous, has wide-reaching implications. Sound travels farther than light or chemicals and thus can be sensed at greater distances by predators, prey, and mates. If sound is a characteristic feature of pelagic ecosystems, it likely plays a role in predator-prey relationships and overall ecosystem dynamics. Our new finding inspires numerous questions such as: Which, how, and why have DSL organisms evolved to create sound, for what do they use it and under what circumstances? Is sound production by DSL organisms truly ubiquitous, or does it depend on the local environment and species composition? How may sound production and perception be adapted to a changing environment? Do predators react to changes in sound? Can sound be used to quantify the composition of mixed-species assemblages, component densities and abundances, and hence be used in stock assessment or predictive modeling?

  11. Quenching behaviour for a singular predator–prey model

    International Nuclear Information System (INIS)

    Ducrot, Arnaud; Guo, Jong-Shenq

    2012-01-01

    In this paper, we study the quenching behaviour for a system of two reaction–diffusion equations arising in the modelling of the spatio-temporal interaction of prey and predator populations in fragile environment. We first provide some sufficient conditions on the initial data to have finite time quenching. Then we classify the initial data to distinguish type I quenching and type II quenching, by introducing a delicate energy functional along with the help of some a priori estimates. Finally, we present some results on the quenching set. It can be a singleton, the whole domain, or a compact subset of the domain

  12. Ineffective crypsis in a crab spider: a prey community perspective

    OpenAIRE

    Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

    2009-01-01

    Cryptic coloration is assumed to be beneficial to predators because of an increased encounter rate with unwary prey. This hypothesis is, however, very rarely, if ever, studied in the field. The aim of this study was to quantify the encounter rate and capture success of an ambush predator, in the field, as a function of its level of colour-matching with the background. We used the crab spider Misumena vatia, which varies its body colour and can thereby match the colour of the flower it hunts u...

  13. Dolphin underwater bait-balling behaviors in relation to group and prey ball sizes.

    Science.gov (United States)

    Vaughn-Hirshorn, Robin L; Muzi, Elisa; Richardson, Jessica L; Fox, Gabriella J; Hansen, Lauren N; Salley, Alyce M; Dudzinski, Kathleen M; Würsig, Bernd

    2013-09-01

    We characterized dusky dolphin (Lagenorhynchus obscurus) feeding behaviors recorded on underwater video, and related behaviors to variation in prey ball sizes, dolphin group sizes, and study site (Argentina versus New Zealand, NZ). Herding behaviors most often involved dolphins swimming around the side or under prey balls, but dolphins in Argentina more often swam under prey balls (48% of passes) than did dolphins in NZ (34% of passes). This result may have been due to differences in group sizes between sites, since groups are larger in Argentina. Additionally, in NZ, group size was positively correlated with proportion of passes that occurred under prey balls (pdolphins in Argentina more often swam through prey balls (8% of attempts) than did dolphins in NZ (4% of attempts). This result may have been due to differences in prey ball sizes between sites, since dolphins fed on larger prey balls in Argentina (>74m(2)) than in NZ (maximum 33m(2)). Additionally, in NZ, dolphins were more likely to swim through prey balls to capture fish when they fed on larger prey balls (p=0.025). Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Prey preferences of aquatic insects: potential implications for the regulation of wetland mosquitoes.

    Science.gov (United States)

    Saha, N; Aditya, G; Saha, G K

    2014-03-01

    Wetlands are potential sites for mosquito breeding and are thus important in the context of public health. The use of chemical and microbial controls is constrained in wetlands in view of their potential impact on the diverse biota. Biological control using generalist aquatic insects can be effective, provided a preference for mosquito larvae is exhibited. The mosquito prey preferences of water bugs and larvae of odonate species were evaluated using chironomid larvae, fish fingerlings and tadpoles as alternative prey. Manly's selectivity (αi ) values with 95% confidence intervals (CIs) were estimated to judge prey preference patterns. Multivariate analysis of variance (manova) and standardized canonical coefficients were used to test the effects of density on prey selectivity. The αi values indicated a significant preference (P insect predators tested for mosquito larvae over the alternative prey as a density-dependent function. On a comparative scale, chironomid larvae had the highest impact as alternative prey. In a multiple-prey experiment, predators showed a similar pattern of preference for mosquito larvae over alternative prey, reflecting a significant (P insect predators can effectively reduce mosquito density in the presence of multiple alternative prey. © 2013 The Royal Entomological Society.

  15. Prey and mound disassembly, manipulation and transport by fire ant collectives

    Science.gov (United States)

    Dutta, Bahnisikha; Monaenkova, Daria; Goodisman, Michael A.; Goldman, Daniel

    Fire ants inhabit subterranean nests covered by a hemispherical mound of soil permeated by narrow ( 1 body length diameter) tunnels. Fire ants can use their mound for long-term food storage [Gayahan &Tschinkel, J. Insect Sci.,2008]. Since mound tunnels are narrow, we expect that in addition to prey manipulation, mound reconfiguration could also be an important aspect of the food storage strategy. Ant colonies collected from wild were allowed to build nests in containers filled with clay soil in the laboratory. These colonies were offered diverse prey embedded with lead markers, including mealworms, crickets and shrimp. Ant-prey-soil interactions on the nest surface were recorded using overhead video and subsurface using x-ray imaging. Individual ants involved in prey storage exhibited three distinct behaviors: prey maneuvering, prey dissection and mound reconfiguration. Small prey (e.g. mealworms) were collectively carried intact into the mound through a tunnel, and then disassembled within the mound. Larger prey (e.g. shrimp) were dismantled into small pieces above the surface and carried to mound tunnels. The bodies of hard medium-sized prey (e.g. crickets) were buried after limb removal and then disassembled and moved into tunnels. Soil reconfiguration occurred in all cases.

  16. Modelling the attack success of planktonic predators: patterns and mechanisms of prey size selectivity

    DEFF Research Database (Denmark)

    Caparroy, P.; Thygesen, Uffe Høgsbro; Visser, Andre

    2000-01-01

    of being captured. By combining the attack success model with previously published hydrodynamic models of predator and prey perception, we examine how predator foraging behaviour and prey perceptive ability affect the size spectra of encountered and captured copepod prey. We examine food size spectra of (i......) a rheotactic cruising predator, (ii) a suspension-feeding hovering copepod and (iii) a larval fish. For rheotactic predators such as carnivorous copepods, a central assumption of the model is that attack is triggered by prey escape reaction, which in turn depends on the deformation rate of the fluid created...

  17. Chlorophacinone residues in mammalian prey at a black-tailed prairie dog colony

    Science.gov (United States)

    Vyas, Nimish B.; Hulse, Craig S.; Rice, Clifford P.

    2012-01-01

    Black-tailed prairie dogs (BTPDs), Cynomys ludovicianus, are an important prey for raptors; therefore, the use of the rodenticide Rozol (0.005% chlorophacinone active ingredient) to control BTPDs raises concern for secondary poisonings resulting from the consumption of contaminated prey by raptors. In the present study, the authors observed Rozol exposure and adverse effects to mammalian prey on 11 of 12 search days of the study. Mammalian hepatic chlorophacinone residues ranged from 0.44 to 7.56 µg/g. Poisoned prey availability was greater than previously reported.

  18. Foraging behavior of larval cod ( Gadus morhua ) influenced by prey density and hunger

    DEFF Research Database (Denmark)

    Munk, Peter

    1995-01-01

    activity, prey selectivity, and hunger in a variable prey environment. Gadus morhua eggs were collected in March 1992 and 1993 from the Kattegat area, Denmark, fertilised and incubated in the laboratory. After hatching, the larvae were transferred to rearing tanks of 172 litres. The behaviour of larvae (6...... their prey size selectivity. Behavioural response was to a large degree determined by the level of hunger, represented by the number of newly ingested prey in the gut. The findings show that cod larvae have a flexible response to changes in feeding conditions and imply that larvae can grow and survive even...

  19. Top down and bottom up selection drives variations in frequency and form of a visual signal.

    Science.gov (United States)

    Yeh, Chien-Wei; Blamires, Sean J; Liao, Chen-Pan; Tso, I-Min

    2015-03-30

    The frequency and form of visual signals can be shaped by selection from predators, prey or both. When a signal simultaneously attracts predators and prey selection may favour a strategy that minimizes risks while attracting prey. Accordingly, varying the frequency and form of the silken decorations added to their web may be a way that Argiope spiders minimize predation while attracting prey. Nonetheless, the role of extraneous factors renders the influences of top down and bottom up selection on decoration frequency and form variation difficult to discern. Here we used dummy spiders and decorations to simulate four possible strategies that the spider Argiope aemula may choose and measured the prey and predator attraction consequences for each in the field. The strategy of decorating at a high frequency with a variable form attracted the most prey, while that of decorating at a high frequency with a fixed form attracted the most predators. These results suggest that mitigating the cost of attracting predators while maintaining prey attraction drives the use of variation in decoration form by many Argiope spp. when decorating frequently. Our study highlights the importance of considering top-down and bottom up selection pressure when devising evolutionary ecology experiments.

  20. Coexistence of structured populations with size-based prey selection

    DEFF Research Database (Denmark)

    Hartvig, Martin; Andersen, Ken Haste

    2013-01-01

    Abstract Species with a large adult-offspring size ratio and a preferred predator–prey mass ratio undergo ontogenetic trophic niche shift(s) throughout life. Trophic interactions between such species vary throughout life, resulting in different species-level interaction motifs depending on the ma......Abstract Species with a large adult-offspring size ratio and a preferred predator–prey mass ratio undergo ontogenetic trophic niche shift(s) throughout life. Trophic interactions between such species vary throughout life, resulting in different species-level interaction motifs depending...... on the maximum adult sizes and population size distributions. We explore the assembly and potential for coexistence of small communities where all species experience ontogenetic trophic niche shifts. The life-history of each species is described by a physiologically structured model and species identity...... there is a large scope for coexistence of two species, the scope for coexistence of three species is limited and we conclude that further trait differentiation is required for coexistence of more species-rich size-structured communities....

  1. Feldspar, Infrared Stimulated Luminescence

    DEFF Research Database (Denmark)

    Jain, Mayank

    2014-01-01

    This entry primarily concerns the characteristics and the origins of infrared-stimulated luminescence in feldspars.......This entry primarily concerns the characteristics and the origins of infrared-stimulated luminescence in feldspars....

  2. Extragalactic infrared astronomy

    International Nuclear Information System (INIS)

    Gondhalekar, P.M.

    1985-05-01

    The paper concerns the field of Extragalactic Infrared Astronomy, discussed at the Fourth RAL Workshop on Astronomy and Astrophysics. Fifteen papers were presented on infrared emission from extragalactic objects. Both ground-(and aircraft-) based and IRAS infrared data were reviewed. The topics covered star formation in galaxies, active galactic nuclei and cosmology. (U.K.)

  3. The other prey-capture silk: Fibres made by glow-worms (Diptera: Keroplatidae) comprise cross-β-sheet crystallites in an abundant amorphous fraction.

    Science.gov (United States)

    Walker, Andrew A; Weisman, Sarah; Trueman, Holly E; Merritt, David J; Sutherland, Tara D

    2015-09-01

    Glow-worms (larvae of dipteran genus Arachnocampa) are restricted to moist habitats where they capture flying prey using snares composed of highly extensible silk fibres and sticky mucus droplets. Little is known about the composition or structure of glow-worm snares, or the extent of possible convergence between glow-worm and arachnid capture silks. We characterised Arachnocampa richardsae silk and mucus using X-ray scattering, Fourier transform infrared spectroscopy and amino acid analysis. Silk but not mucus contained crystallites of the cross-β-sheet type, which occur in unrelated insect silks but have not been reported previously in fibres used for prey capture. Mucus proteins were rich in Gly (28.5%) and existed in predominantly a random coil structure, typical of many adhesive proteins. In contrast, the silk fibres were unusually rich in charged and polar residues, particularly Lys (18.1%), which we propose is related to their use in a highly hydrated state. Comparison of X-ray scattering, infrared spectroscopy and amino acid analysis data suggests that silk fibres contain a high fraction of disordered protein. We suggest that in the native hydrated state, silk fibres are capable of extension via deformation of both disordered regions and cross-β-sheet crystallites, and that high extensibility is an adaptation promoting successful prey capture. This study illustrates the rich variety of protein motifs that are available for recruitment into biopolymers, and how convergently evolved materials can nevertheless be based on fundamentally different protein structures. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

  4. The erroneous signals of detection theory.

    Science.gov (United States)

    Trimmer, Pete C; Ehlman, Sean M; McNamara, John M; Sih, Andrew

    2017-10-25

    Signal detection theory has influenced the behavioural sciences for over 50 years. The theory provides a simple equation that indicates numerous 'intuitive' results; e.g. prey should be more prone to take evasive action (in response to an ambiguous cue) if predators are more common. Here, we use analytical and computational models to show that, in numerous biological scenarios, the standard results of signal detection theory do not apply; more predators can result in prey being less responsive to such cues. The standard results need not apply when the probability of danger pertains not just to the present, but also to future decisions. We identify how responses to risk should depend on background mortality and autocorrelation, and that predictions in relation to animal welfare can also be reversed from the standard theory. © 2017 The Author(s).

  5. Boundedness and permanence in a class of periodic time-dependent predator-prey system with prey dispersal and predator density-independence

    International Nuclear Information System (INIS)

    Zhang Long; Teng Zhidong

    2008-01-01

    In this paper, we study two species predator-prey Lotka-Volterra type dispersal system with periodic coefficients, in which the prey species can disperse among n patches, while the density-independent predator species is confined to one of the patches and cannot disperse. Sufficient conditions on the boundedness, permanence and existence of positive periodic solution for this system are established. The theoretical results are confirmed by a special example and numerical simulations

  6. Joint evolution of predator body size and prey-size preference.

    NARCIS (Netherlands)

    Troost, T.A.; Kooi, B.W.; Dieckmann, U.

    2007-01-01

    We studied the joint evolution of predator body size and prey-size preference based on dynamic energy budget theory. The predators' demography and their functional response are based on general eco-physiological principles involving the size of both predator and prey. While our model can account for

  7. Effects of dams on downstream molluscan predator-prey interactions in the Colorado River estuary.

    Science.gov (United States)

    Smith, Jansen A; Handley, John C; Dietl, Gregory P

    2018-05-30

    River systems worldwide have been modified for human use and the downstream ecological consequences are often poorly understood. In the Colorado River estuary, where upstream water diversions have limited freshwater input during the last century, mollusc remains from the last several hundred years suggest widespread ecological change. The once abundant clam Mulinia modesta has undergone population declines of approximately 94% and populations of predators relying on this species as a food source have probably declined, switched to alternative prey species or both. We distinguish between the first two hypotheses using a null model of predation preference to test whether M. modesta was preyed upon selectively by the naticid snail, Neverita reclusiana , along the estuary's past salinity gradient. To evaluate the third hypothesis, we estimate available prey biomass today and in the past, assuming prey were a limiting resource. Data on the frequency of drill holes-identifiable traces of naticid predation on prey shells-showed several species, including M. modesta , were preferred prey. Neverita reclusiana was probably able to switch prey. Available prey biomass also declined, suggesting the N. reclusiana population probably also declined. These results indicate a substantial change to the structure of the benthic food web. Given the global scale of water management, such changes have probably also occurred in many of the world's estuaries. © 2018 The Author(s).

  8. Joint evolution of predator body size and prey-size preference

    NARCIS (Netherlands)

    Troost, Tineke; Kooi, Bob; Dieckmann, Ulf

    2007-01-01

    We studied the joint evolution of predator body size and prey-size preference based on dynamic energy budget theory. The predators’ demography and their functional response are based on general eco-physiological principles involving the size of both predator and prey. While our model can account

  9. Intra-seasonal Strategies Based on Energy Budgets in a Dynamic Predator-Prey Game

    NARCIS (Netherlands)

    Staňková, K.; Abate, A.; Sabelis, M.W.; Křivan, V.; Zaccour, G.

    2013-01-01

    We propose a game-theoretical model to describe intra-seasonal predator-prey interactions between predatory mites (Acari: Phytoseiidae) and prey mites (also called fruit-tree red spider mites) (Acari: Tetranychidae) that feed on leaves of apple trees. Its parameters have been instantiated based on

  10. Clay Caterpillar Whodunit: A Customizable Method for Studying Predator-Prey Interactions in the Field

    Science.gov (United States)

    Curtis, Rachel; Klemens, Jeffrey A.; Agosta, Salvatore J.; Bartlow, Andrew W.; Wood, Steve; Carlson, Jason A.; Stratford, Jeffrey A.; Steele, Michael A.

    2013-01-01

    Predator-prey dynamics are an important concept in ecology, often serving as an introduction to the field of community ecology. However, these dynamics are difficult for students to observe directly. We describe a methodology that employs model caterpillars made of clay to estimate rates of predator attack on a prey species. This approach can be…

  11. Coexistence in a One-Predator, Two-Prey System with Indirect Effects

    Directory of Open Access Journals (Sweden)

    Renato Colucci

    2013-01-01

    Full Text Available We study the dynamics of a one-predator, two-prey system in which the predator has an indirect effect on the preys. We show that, in presence of the indirect effect term, the system admits coexistence of the three populations while, if we disregard it, at least one of the populations goes to extinction.

  12. Stomach fullness shapes prey choice decisions in crab plovers (Dromas ardeola)

    NARCIS (Netherlands)

    Gommer, Roy; Bom, Roeland A.; Fijen, Thijs P.M.; Gils, Van Jan A.

    2018-01-01

    Foragers whose energy intake rate is constrained by search and handling time should, according to the contingency model (CM), select prey items whose profitability exceeds or equals the forager’s long-term average energy intake rate. This rule does not apply when prey items are found and ingested at

  13. An impulsive predator-prey system with modified Leslie-Gower and Holling type II schemes

    International Nuclear Information System (INIS)

    Guo Hongjian; Song Xinyu

    2008-01-01

    An impulsive predator-prey system with modified Leslie-Gower and Holling-type II schemes is presented. By using the Floquet theory of impulsive equation and small amplitude perturbation method, the globally asymptotical stability of prey-free positive periodic solution and the permanence of system are discussed. The corresponding threshold conditions are obtained respectively. Finally, numerical simulations are given

  14. Recognising one's enemies : a functional approach to risk assessment by prey

    NARCIS (Netherlands)

    Grostal, P.; Dicke, M.

    2000-01-01

    Little has been done to compare the relative importance of various mechanisms through which prey assess the potential risk from natural enemies. We used predator-naive spider mites (Tetranychus urticae, Tetranychidae) to (1) compare the responses of prey to chemical cues from enemy and non-enemy

  15. The diet of otters ( Lutra lutra L.) in Danish freshwater habitats : comparisons of prey fish populations

    DEFF Research Database (Denmark)

    Taastrom, H.M.; Jacobsen, Lene

    1999-01-01

    Otter spraints from five Danish freshwater localities were analysed. In all localities fish was the main prey (76-99% of estimated bulk), especially in winter. Depending on locality, the prey fish mainly consisted of cyprinids (Cyprinidae), percids (Percidae) or salmonids (Salmonidae). Seasonal v...

  16. What you need is what you eat? Prey selection by the bat Myotis daubentonii

    NARCIS (Netherlands)

    Vesterinen, Eero; Ruokolainen, Lasse; Wahlberg, Niklas; Pena, Carlos; Roslin, Tomas; Laine, V.; Vasko, Ville; Sääksjärvi, Ilari; Norrdahl, Kai; Lilley, Thomas

    2016-01-01

    Optimal foraging theory predicts that predators are selective when faced with abundant prey, but become less picky when prey gets sparse. Insectivorous bats in temperate regions are faced with the challenge of building up fat reserves vital for hibernation during a period of decreasing arthropod

  17. Effects of an infectious fungus, Batrachochytrium dendrobatidis, on amphibian predator-prey interactions.

    Directory of Open Access Journals (Sweden)

    Barbara A Han

    2011-02-01

    Full Text Available The effects of parasites and pathogens on host behaviors may be particularly important in predator-prey contexts, since few animal behaviors are more crucial for ensuring immediate survival than the avoidance of lethal predators in nature. We examined the effects of an emerging fungal pathogen of amphibians, Batrachochytrium dendrobatidis, on anti-predator behaviors of tadpoles of four frog species. We also investigated whether amphibian predators consumed infected prey, and whether B. dendrobatidis caused differences in predation rates among prey in laboratory feeding trials. We found differences in anti-predator behaviors among larvae of four amphibian species, and show that infected tadpoles of one species (Anaxyrus boreas were more active and sought refuge more frequently when exposed to predator chemical cues. Salamander predators consumed infected and uninfected tadpoles of three other prey species at similar rates in feeding trials, and predation risk among prey was unaffected by B. dendrobatidis. Collectively, our results show that even sub-lethal exposure to B. dendrobatidis can alter fundamental anti-predator behaviors in some amphibian prey species, and suggest the unexplored possibility that indiscriminate predation between infected and uninfected prey (i.e., non-selective predation could increase the prevalence of this widely distributed pathogen in amphibian populations. Because one of the most prominent types of predators in many amphibian systems is salamanders, and because salamanders are susceptible to B. dendrobatidis, our work suggests the importance of considering host susceptibility and behavioral changes that could arise from infection in both predators and prey.

  18. Estimation of feeding patterns for piscivorous fish using individual prey data from stomach contents

    DEFF Research Database (Denmark)

    Berg, Casper Willestofte; Temming, Axel

    2011-01-01

    The problem of estimating temporal feeding patterns using stomach data is considered, where the time of ingestion for each prey item can be predicted through a gastric evacuation model. The arrival of prey is modelled as a nonhomogeneous Poisson process with known periodic intensity. A maximum...

  19. Encounter success of free-ranging marine predator movements across a dynamic prey landscape.

    Science.gov (United States)

    Sims, David W; Witt, Matthew J; Richardson, Anthony J; Southall, Emily J; Metcalfe, Julian D

    2006-05-22

    Movements of wide-ranging top predators can now be studied effectively using satellite and archival telemetry. However, the motivations underlying movements remain difficult to determine because trajectories are seldom related to key biological gradients, such as changing prey distributions. Here, we use a dynamic prey landscape of zooplankton biomass in the north-east Atlantic Ocean to examine active habitat selection in the plankton-feeding basking shark Cetorhinus maximus. The relative success of shark searches across this landscape was examined by comparing prey biomass encountered by sharks with encounters by random-walk simulations of 'model' sharks. Movements of transmitter-tagged sharks monitored for 964 days (16754 km estimated minimum distance) were concentrated on the European continental shelf in areas characterized by high seasonal productivity and complex prey distributions. We show movements by adult and sub-adult sharks yielded consistently higher prey encounter rates than 90% of random-walk simulations. Behavioural patterns were consistent with basking sharks using search tactics structured across multiple scales to exploit the richest prey areas available in preferred habitats. Simple behavioural rules based on learned responses to previously encountered prey distributions may explain the high performances. This study highlights how dynamic prey landscapes enable active habitat selection in large predators to be investigated from a trophic perspective, an approach that may inform conservation by identifying critical habitat of vulnerable species.

  20. Are We Really the Prey? Nanotechnology as Science and Science Fiction

    Science.gov (United States)

    Bowman, Diana M.; Hodge, Graeme A.; Binks, Peter

    2007-01-01

    Popular culture can play a significant role in shaping the acceptance of evolving technologies, with nanotechnology likely to be a case in point. The most popular fiction work to date in this arena has been Michael Crichton's techno-thriller "Prey," which fuses together nanotechnology science with science fiction. Within the context of "Prey,"…

  1. Demographic consequences of predators on prey: trait and density mediated effects on mosquito larvae in containers.

    Directory of Open Access Journals (Sweden)

    Barry W Alto

    Full Text Available Predators may affect prey population growth and community diversity through density mediated lethal and trait mediated non-lethal effects that influence phenotypic traits of prey. We tested experimentally the roles of thinning the density of prey (lethality in the absence of predator cues and density and trait mediated effects (lethality + intimidation of predatory midge Corethrella appendiculata on competing native and invasive mosquito prey. Predator-mediated reductions in prey and density reductions in the absence of C. appendiculata resulted in lower percent survivorship to adulthood and estimates of the finite rate of increase (λ' for invasive mosquito Aedes albopictus relative to that of controls. In most instances, thinning the density of prey in the absence, but not in the presence, of C. appendiculata cues resulted in lower survivorship to adulthood and λ' for native mosquito Aedes triseriatus relative to that of controls. Together, these results suggested trait mediated effects of C. appendiculata specific to each species of mosquito prey. Release from intraspecific competition attributable to density reductions in the absence, but not in the presence, of C. appendiculata enhanced growth and lengthened adult lifespan relative to that of controls for A. albopictus but not A. triseriatus. These results show the importance of predator-mediated density and trait mediated effects on phenotypic traits and populations of invasive and native mosquitoes. Species-specific differences in the phenotypic responses of prey may be due, in part, to longer evolutionary history of C. appendiculata with A. triseriatus than A. albopictus.

  2. Effective prey attraction in the rare Drosophyllum lusitanicum, a flypaper-trap carnivorous plant.

    Science.gov (United States)

    Bertol, Nils; Paniw, Maria; Ojeda, Fernando

    2015-05-01

    Carnivorous plants have unusually modified leaves to trap insects as an adaptation to low-nutrient environments. Disparate mechanisms have been suggested as luring traits to attract prey insects into their deadly leaves, ranging from very elaborate to none at all. Drosophyllum lusitanicum is a rare carnivorous plant with a common flypaper-trap mechanism. Here we tested whether Drosophyllum plants lure prey insects into their leaves or they act just as passive traps. We compared prey capture between live, potted plants and Drosophyllum-shaped artificial mimics coated with odorless glue. Since this species is insect-pollinated, we also explored the possible existence of a pollinator-prey conflict by quantifying the similarity between the pollination and prey guilds in a natural population. All experiments were done in southern Spain. The sticky leaves of Drosophyllum captured significantly more prey than mimics, particularly small dipterans. Prey attraction, likely exerted by scent or visual cues, seems to be unrelated to pollinator attraction by flowers, as inferred from the low similarity between pollinator and prey insect faunas found in this species. Our results illustrate the effectiveness of this carnivorous species at attracting insects to their flypaper-trap leaves. © 2015 Botanical Society of America, Inc.

  3. Generalist predator, cyclic voles and cavity nests: testing the alternative prey hypothesis.

    Science.gov (United States)

    Pöysä, Hannu; Jalava, Kaisa; Paasivaara, Antti

    2016-12-01

    The alternative prey hypothesis (APH) states that when the density of the main prey declines, generalist predators switch to alternative prey and vice versa, meaning that predation pressure on the alternative prey should be negatively correlated with the density of the main prey. We tested the APH in a system comprising one generalist predator (pine marten, Martes martes), cyclic main prey (microtine voles, Microtus agrestis and Myodes glareolus) and alternative prey (cavity nests of common goldeneye, Bucephala clangula); pine marten is an important predator of both voles and common goldeneye nests. Specifically, we studied whether annual predation rate of real common goldeneye nests and experimental nests is negatively associated with fluctuation in the density of voles in four study areas in southern Finland in 2000-2011. Both vole density and nest predation rate varied considerably between years in all study areas. However, we did not find support for the hypothesis that vole dynamics indirectly affects predation rate of cavity nests in the way predicted by the APH. On the contrary, the probability of predation increased with vole spring abundance for both real and experimental nests. Furthermore, a crash in vole abundance from previous autumn to spring did not increase the probability of predation of real nests, although it increased that of experimental nests. We suggest that learned predation by pine marten individuals, coupled with efficient search image for cavities, overrides possible indirect positive effects of high vole density on the alternative prey in our study system.

  4. BEHAVIOR AND PREY OF NESTING RED-SHOULDERED HAWKS IN SOUTHWESTERN OHIO

    Science.gov (United States)

    We used direct observations to quantify prey types, prey delivery rate, and adult and nestling behavior at nests of Red-shouldered Hawks (Buteo lineatus) in suburban southwestern Ohio. Twenty-one nests were observed for a total of 256 hr in 1997-2001. Small mammals made up the ...

  5. Assessing diet compositions of Lake Ontario predators using fatty acid profiles of prey fishes

    Science.gov (United States)

    Happell, Austin; Pattridge, Robert; Rinchard, Jacques; Walsh, Maureen

    2017-01-01

    Fatty acid profiles are used in food web studies to assess trophic interactions between predator and prey. The present study provides the first comprehensive fatty acid dataset for important prey and predator species in Lake Ontario. Three major prey fish (alewife, rainbow smelt, and round goby) were collected at three sites along the southern shore of Lake Ontario during the spring and fall of 2013, and predator species were collected in similar locations during the summer of 2013. Fatty acid compositions were compared among all prey species, all predator species, and information from both predator and prey was used to infer foraging differences among predators. Seasonal differences in fatty acids were found within each prey species studied. Differences among prey species were greater than any spatio-temporal differences detected within species. Fatty acids of predators revealed species-specific differences that matched known foraging habits. Chinook and Coho salmon, which are known to select alewife as their dominant prey item, had relatively little variation in fatty acid profiles. Conversely, brown trout, lake trout, yellow perch and esocids had highly variable fatty acid profiles and likely highly variable diet compositions. In general, our data suggested three dominant foraging patterns: 1) diet composed of nearly exclusively alewife for Chinook and Coho Salmon; 2) a mixed diet of alewife and round goby for brown and lake trout, and both rock and smallmouth bass; 3) a diet that is likely comprised of forage fishes other than those included in our study for northern pike and chain pickerel.

  6. Correlation between the seasonal distribution of harbour porpoises and their prey in the Sound, Baltic Sea

    DEFF Research Database (Denmark)

    Sveegaard, Signe; Andreasen, Heidi; Mouritsen, Kim N.

    2012-01-01

    herring and Atlantic cod were equally important during the low-density season. Prey availability and predictability are suggested as the main drivers for harbour porpoise distribution, and this could be caused by the formation of frontal zones in spring in the northern part of the Sound, leading to prey...

  7. Extinction in a generalized Lotka-Volterra predator-prey model

    Directory of Open Access Journals (Sweden)

    Azmy S. Ackleh

    2000-01-01

    Full Text Available In this paper we discuss the asymptotic behavior of a predator-prey model with distributed growth and mortality rates. We exhibit simple criteria on the parameters which guarantee that all subpopulations but one predator-prey pair are driven to extinction as t→∞. Finally, we present numerical simulations to illustrate the theoretical results.

  8. Digestion rates of prey eaten by intertidal sea anemones from the ...

    African Journals Online (AJOL)

    Digestion rates were determined for natural prey items offered to each of seven species of sea anemones found at Wooley's Pool in False Say and to the single species (Bunodactis reynaudl) recorded at Siouberg on the Atlantic coast of the south-western Cape, South Africa.This was done by examining prey items removed ...

  9. Flocking and feeding in the fiddler crab (UCA tangeri) : Prey availability as risk-taking behaviour

    NARCIS (Netherlands)

    Ens, B; KLAASSEN, M; ZWARTS, L

    1993-01-01

    For a full understanding of prey availability, it is necessary to study risk-taking behaviour of the prey. Fiddler crabs are ideally suited for such a study, as they have to leave their safe burrow to feed on the surface of the intertidal flats during low tide, thereby exposing themselves to avian

  10. Effect of location and season on the arthropod prey of Nycteris ...

    African Journals Online (AJOL)

    Analysis of culled arthropod prey parts collected from beneath four feeding perches was used to assess prey taken by Nycteris grandis from November 1987 to May 1988. The perches were located along the Zambezi River in Mana Pools National Park in Zimbabwe.With the exception of an occasional solifugid, N. grandis ...

  11. Arthropod prey of nestling red-cockaded woodpeckers in the upper coastal plain of South Carolina

    Science.gov (United States)

    James L. Hanula; Kathleen E. Franzreb

    1995-01-01

    Four nest cavities of the Red-cockaded Woodpecker (Picoides borealis) were monitored with automatic cameras to determine the prey selected to feed nestlings. Twelve adults were photographed making nearly 3000 nest visits. Prey in 28 arthropod taxa were recognizable in 65% of the photographic slides. Wood roaches in the genus (Parcoblutta...

  12. Influence of prey abundance and abiotic factors on the long-term ...

    African Journals Online (AJOL)

    ... the home-range distribution of spotted grunter. Spatial distribution of prey appears to be a dominant factor influencing home-range parameters of this species within an intermittently open estuary. Keywords: acoustic telemetry, East Kleinemonde Estuary, estuarine fish, movement behaviour, prey abundance, South Africa ...

  13. Senses & Sensibility: Predator-Prey Experiments Reveal How Fish Perceive & Respond to Threats

    Science.gov (United States)

    Jones, Jason; Holloway, Barbara; Ketcham, Elizabeth; Long, John

    2008-01-01

    The predator-prey relationship is one of the most recognizable and well-studied animal relationships. One of the more striking aspects of this relationship is the differential natural selection pressure placed on predators and their prey. This differential pressure results from differing costs of failure, the so-called life-dinner principle. If a…

  14. Birds exploit herbivore-induced plant volatiles to locate herbivorous prey

    NARCIS (Netherlands)

    Amo, L.; Jansen, J.J.; Dam, van N.M.; Dicke, M.; Visser, M.E.

    2013-01-01

    Arthropod herbivory induces plant volatiles that can be used by natural enemies of the herbivores to find their prey. This has been studied mainly for arthropods that prey upon or parasitise herbivorous arthropods but rarely for insectivorous birds, one of the main groups of predators of herbivorous

  15. Along Came a Spider: Using Live Arthropods in a Predator-Prey Activity

    Science.gov (United States)

    Richardson, Matthew L.; Hari, Janice

    2011-01-01

    We developed a predator-prey activity with eighth-grade students in which they used wolf spiders ("Lycosa carolinensis"), house crickets ("Acheta domestica"), and abiotic factors to address how (1) adaptations in predators and prey shape their interaction and (2) abiotic factors modify the interaction between predators and…

  16. Clock-Controlled Prey-Predator Dynamics : Temporal Segregation of Activities

    OpenAIRE

    Hiroaki, DAIDO; Department of Mathematical Sciences, Graduate School of Engineering, University of Osaka Prefecture

    2003-01-01

    A new type of mathematical model of prey-predator dynamics is proposed. This model takes into account the fact that the daily activities of animals are governed by their body clocks. On the basis of it, we investigate the conditions under which the prey and predator can segregate into diurnal and nocturnal habits on a timescale that is short compared to evolutionary timescales.

  17. Foraging efficiency of a predator flock for randomly moving prey: A simulation study

    Science.gov (United States)

    Lee, Sang-Hee; Kwon, Ohsung

    2016-03-01

    Flocking behavior of animals is highly advantageous for taking food resources. The degree of the advantage is related to the ability of flock members to detect their prey and the mobility of prey individuals. In this study, to explore the relation, we constructed a model to simulate a predator flock and its randomly moving prey. The predator members have the prey detection ability, which was characterized as sensing distance, R, and a sensing angle, θ. The mobility of the prey individuals was characterized as the maximum traveling distance of an iteration time step, L. The relative flock foraging efficiency, ɛ, was defined as ɛ = 1 - (Td/Tup). Tup and Td represent the spent time for the flock to eat all prey individuals and to uptake the last remaining 10% prey, respectively. Simulation results showed that ɛ increased, maximized, and decreased with the increase of R, regardless of L. As the number of prey, N, increased, the tendency of the increasing and decreasing was diluted. The result was briefly discussed in relation to the flock foraging behavior and the development of the model toward applications for real ecosystems.

  18. Seasonal and among-stream variation in predator encounter rates for fish prey

    Science.gov (United States)

    Bret C. Harvey; Rodney J. Nakamoto

    2013-01-01

    Recognition that predators have indirect effects on prey populations that may exceed their direct consumptive effects highlights the need for a better understanding of spatiotemporal variation in predator–prey interactions. We used photographic monitoring of tethered Rainbow Trout Oncorhynchus mykiss and Cutthroat Trout O. clarkii to quantify predator encounter rates...

  19. Challenges to a molecular approach to prey identification in the Burmese python, Python molurus bivittatus

    Science.gov (United States)

    Falk, Bryan; Reed, Robert N.

    2015-01-01

    Molecular approaches to prey identification are increasingly useful in elucidating predator–prey relationships, and we aimed to investigate the feasibility of these methods to document the species identities of prey consumed by invasive Burmese pythons in Florida. We were particularly interested in the diet of young snakes, because visual identification of prey from this size class has proven difficult. We successfully extracted DNA from the gastrointestinal contents of 43 young pythons, as well as from several control samples, and attempted amplification of DNA mini-barcodes, a 130-bp region of COX1. Using a PNA clamp to exclude python DNA, we found that prey DNA was not present in sufficient quality for amplification of this locus in 86% of our samples. All samples from the GI tracts of young pythons contained only hair, and the six samples we were able to identify to species were hispid cotton rats. This suggests that young Burmese pythons prey predominantly on small mammals and that prey diversity among snakes of this size class is low. We discuss prolonged gastrointestinal transit times and extreme gastric breakdown as possible causes of DNA degradation that limit the success of a molecular approach to prey identification in Burmese pythons

  20. Putting prey and predator into the CO2 equation--qualitative and quantitative effects of ocean acidification on predator-prey interactions.

    Science.gov (United States)

    Ferrari, Maud C O; McCormick, Mark I; Munday, Philip L; Meekan, Mark G; Dixson, Danielle L; Lonnstedt, Öona; Chivers, Douglas P

    2011-11-01

    Little is known about the impact of ocean acidification on predator-prey dynamics. Herein, we examined the effect of carbon dioxide (CO(2)) on both prey and predator by letting one predatory reef fish interact for 24 h with eight small or large juvenile damselfishes from four congeneric species. Both prey and predator were exposed to control or elevated levels of CO(2). Mortality rate and predator selectivity were compared across CO(2) treatments, prey size and species. Small juveniles of all species sustained greater mortality at high CO(2) levels, while large recruits were not affected. For large prey, the pattern of prey selectivity by predators was reversed under elevated CO(2). Our results demonstrate both quantitative and qualitative consumptive effects of CO(2) on small and larger damselfish recruits respectively, resulting from CO(2)-induced behavioural changes likely mediated by impaired neurological function. This study highlights the complexity of predicting the effects of climate change on coral reef ecosystems. © 2011 Blackwell Publishing Ltd/CNRS.

  1. Myxobacteria Are Able to Prey Broadly upon Clinically-Relevant Pathogens, Exhibiting a Prey Range Which Cannot Be Explained by Phylogeny

    Directory of Open Access Journals (Sweden)

    Paul G. Livingstone

    2017-08-01

    Full Text Available Myxobacteria are natural predators of microorganisms and the subjects of concerted efforts to identify novel antimicrobial compounds. Myxobacterial predatory activity seems to require more than just the possession of specific antimicrobial metabolites. Thus a holistic approach to studying predation promises novel insights into antimicrobial action. Here, we report the isolation of 113 myxobacteria from samples of soil taken from a range of habitats in mid Wales. Predatory activity of each isolate was quantified against a panel of clinically important prey organisms, including Klebsiella pneumoniae, Proteus mirabilis, Candida albicans, Enterococcus faecalis, and three species of Staphylococcus. Myxobacterial isolates exhibited a wide range of predation activity profiles against the panel of prey. Efficient predation of all prey by isolates within the collection was observed, with K. pneumoniae and C. albicans proving particularly susceptible to myxobacterial predation. Notably efficient predators tended to be proficient at predating multiple prey organisms, suggesting they possess gene(s encoding a broad range killing activity. However, predatory activity was not congruent with phylogeny, suggesting prey range is subject to relatively rapid specialization, potentially involving lateral gene transfer. The broad but patchy prey ranges observed for natural myxobacterial isolates also implies multiple (potentially overlapping genetic determinants are responsible for dictating predatory activity.

  2. Introductory survey for wireless infrared communications

    Directory of Open Access Journals (Sweden)

    Munsif Ali Jatoi

    2014-08-01

    Full Text Available Wireless infrared communications can be defined as the propagation of light waves in free space using infrared radiation whose range is 400–700 nm. This range corresponds to frequencies of hundreds of terahertz, which is high for higher data rate applications. Wireless infrared is applied for higher data rates applications such as wireless computing, wireless video and wireless multimedia communication applications. Introduced by Gfeller, this field has grown with different link configurations, improved transmitter efficiency, increased receiver responsivity and various multiple access techniques for improved quality. Errors are caused because of background light, which causes degradation overall system performance. Error correction techniques are used to remove the errors caused during transmission. This study provides a brief account on field theory used for error correction in wireless infrared systems. The results are produced in terms of bit error rate and signal-to-noise ratio for various bit lengths to show the ability of encoding and decoding algorithms.

  3. Foraging behaviour and prey size spectra of larval herring Clupea harengus

    DEFF Research Database (Denmark)

    Munk, Peter

    1992-01-01

    size groups of larval herring Clupea harengus L. were studied when preying on 6 size groups of copepods. Larval swimming and attack behaviour changed with prey size and were related to the ratio between prey length and larval length. The effective search rate showed a maximum when prey length was about......, that the available biomass of food as a proportion of the predator biomass will not increase. In order to assess the uniformity of relative prey size spectra of herring larvae and their background in larval foraging behaviour, a set of experimental and field investigations has been carried out. In the experiments, 4...... in the biomass spectra of the environment is important to larval growth and survival....

  4. Influence of vegetation on the nocturnal foraging behaviors and vertebrate prey capture by endangered Burrowing Owls

    Directory of Open Access Journals (Sweden)

    Alan Marsh

    2014-06-01

    Full Text Available Restrictions in technology have limited past habitat selection studies for many species to the home-range level, as a finer-scale understanding was often not possible. Consequently, these studies may not identify the true mechanism driving habitat selection patterns, which may influence how such results are applied in conservation. We used GPS dataloggers with digital video recorders to identify foraging modes and locations in which endangered Burrowing Owls (Athene cunicularia captured prey. We measured the coarse and fine-scale characteristics of vegetation at locations in which owls searched for, versus where they caught, vertebrate prey. Most prey items were caught using hover-hunting. Burrowing Owls searched for, and caught, vertebrate prey in all cover types, but were more likely to kill prey in areas with sparse and less dense vegetative cover. Management strategies designed to increase Burrowing Owl foraging success in the Canadian prairies should try to ensure a mosaic of vegetation heights across cover types.

  5. Prey selection and feeding habits of the large carnivores in the Southern Kalahari

    Directory of Open Access Journals (Sweden)

    M. G. L Mills

    1984-12-01

    Full Text Available Prey selection and feeding habits of lions Panthera leo, spotted hyaenas Crocuta crocuta, cheetahs Acinonyx jubatus and leopards Panthera pardus are investigated. Lions kill mainly adult gemsbok Oryx gazella and blue wildebeest Connochaetes taurinus, tending to select older animals of both species and males in the case of gemsbok. Spotted hyaenas also prey mainly on gemsbok and wildebeest, but select for juveniles, particularly from gemsbok. Cheetahs prey heavily on springbok Antidorcas marsupialis lambs and then on adult males and older individuals. Leopards also prey relatively heavily on springbok, but appear to have a wider diet than cheetahs do. It is concluded that predators generally have a small impact on their prey populations in the southern Kalahari, although in the case of springbok they do appear to influence the structure of the population.

  6. Prey selection by the Barn Owl Tyto alba (Scopoli, 1769 in captivity

    Directory of Open Access Journals (Sweden)

    V. Vanitha

    2009-07-01

    Full Text Available We investigated prey selection of the Barn Owl Tyto alba under captive conditions where birds were allowed to choose among individuals of varying size from four field rodent species: Bandicota bengalensis, Millardia meltada, Tatera indica and Mus booduga. Owls showed little species preference and a tendency to favour the medium weight class in all prey species except M. booduga. Preference for body parts consumed varied according to prey size, ranging from the head alone in the large weight class to the entire body in the small weight class. Biochemical measurements showed that protein, carbohydrate and lipid levels were higher respectively in the brain, liver and muscles of all three species and weight classes studied. The preference for medium weight prey despite a lower nutrient content compared to large weight prey is attributed to a greater ease of capture.

  7. Predator-prey interactions as macro-scale drivers of species diversity in mammals

    DEFF Research Database (Denmark)

    Sandom, Christopher James; Sandel, Brody Steven; Dalby, Lars

    Background/Question/Methods Understanding the importance of predator-prey interactions for species diversity is a central theme in ecology, with fundamental consequences for predicting the responses of ecosystems to land use and climate change. We assessed the relative support for different...... mechanistic drivers of mammal species richness at macro-scales for two trophic levels: predators and prey. To disentangle biotic (i.e. functional predator-prey interactions) from abiotic (i.e. environmental) and bottom-up from top-down determinants we considered three hypotheses: 1) environmental factors...... that determine ecosystem productivity drive prey and predator richness (the productivity hypothesis, abiotic, bottom-up), 2) consumer richness is driven by resource diversity (the resource diversity hypothesis, biotic, bottom-up) and 3) consumers drive richness of their prey (the top-down hypothesis, biotic, top...

  8. Sperm whale predator-prey interactions involve chasing and buzzing, but no acoustic stunning

    DEFF Research Database (Denmark)

    Fais, Andrea; Johnson, M.; Wilson, Maria

    2016-01-01

    The sperm whale carries a hypertrophied nose that generates powerful clicks for long-range echolocation. However, it remains a conundrum how this bizarrely shaped apex predator catches its prey. Several hypotheses have been advanced to propose both active and passive means to acquire prey......, including acoustic debilitation of prey with very powerful clicks. Here we test these hypotheses by using sound and movement recording tags in a fine-scale study of buzz sequences to relate the acoustic behaviour of sperm whales with changes in acceleration in their head region during prey capture attempts....... We show that in the terminal buzz phase, sperm whales reduce inter-click intervals and estimated source levels by 1-2 orders of magnitude. As a result, received levels at the prey are more than an order of magnitude below levels required for debilitation, precluding acoustic stunning to facilitate...

  9. Bat calls while preying: A method for reconstructing the signal emitted by a directional sound source

    DEFF Research Database (Denmark)

    Guarato, Francesco; Hallam, John

    2010-01-01

    Understanding and modeling bat biosonar behavior should take into account what the bat actually emitted while exploring the surrounding environment. Recording of the bat calls could be performed by means of a telemetry system small enough to sit on the bat head, though filtering due to bat...... directivity affects recordings and not all bat species are able to carry such a device. Instead, remote microphone recordings of the bat calls could be processed by means of a mathematical method that estimates bat head orientation as a first step before calculating the amplitudes of each call for each...... and discussed. A further improvement of the method is necessary as its performance for call reconstruction strongly depends on correct choice of the sample at which the recorded call is thought to start in each microphone data set....

  10. Selective olfactory attention of a specialised predator to intraspecific chemical signals of its prey

    Czech Academy of Sciences Publication Activity Database

    Cardenas, M.; Jiroš, Pavel; Pekár, S.

    2012-01-01

    Roč. 99, č. 8 (2012), s. 597-605 ISSN 0028-1042 Institutional research plan: CEZ:AV0Z40550506 Keywords : airborne cues * ants * chemoreception * Zodariidae * olfactometer Subject RIV: CC - Organic Chemistry Impact factor: 2.144, year: 2012

  11. On the sensitivity of heterodyne detectors in far infrared astronomy

    International Nuclear Information System (INIS)

    Bueren, H.G. van

    1976-01-01

    The signal-to-noise ratio of astronomical heterodyne detection infrared spectrographs is considered, taking into account background, linewidth and seeing effects. A comparison with incoherent detector systems is presented. (author)

  12. When hawks attack: animal-borne video studies of goshawk pursuit and prey-evasion strategies

    Science.gov (United States)

    Kane, Suzanne Amador; Fulton, Andrew H.; Rosenthal, Lee J.

    2015-01-01

    Video filmed by a camera mounted on the head of a Northern Goshawk (Accipiter gentilis) was used to study how the raptor used visual guidance to pursue prey and land on perches. A combination of novel image analysis methods and numerical simulations of mathematical pursuit models was used to determine the goshawk's pursuit strategy. The goshawk flew to intercept targets by fixing the prey at a constant visual angle, using classical pursuit for stationary prey, lures or perches, and usually using constant absolute target direction (CATD) for moving prey. Visual fixation was better maintained along the horizontal than vertical direction. In some cases, we observed oscillations in the visual fix on the prey, suggesting that the goshawk used finite-feedback steering. Video filmed from the ground gave similar results. In most cases, it showed goshawks intercepting prey using a trajectory consistent with CATD, then turning rapidly to attack by classical pursuit; in a few cases, it showed them using curving non-CATD trajectories. Analysis of the prey's evasive tactics indicated that only sharp sideways turns caused the goshawk to lose visual fixation on the prey, supporting a sensory basis for the surprising frequency and effectiveness of this tactic found by previous studies. The dynamics of the prey's looming image also suggested that the goshawk used a tau-based interception strategy. We interpret these results in the context of a concise review of pursuit–evasion in biology, and conjecture that some prey deimatic ‘startle’ displays may exploit tau-based interception. PMID:25609783

  13. How much is too much? Assessment of prey consumption by Magellanic penguins in Patagonian colonies.

    Directory of Open Access Journals (Sweden)

    Juan E Sala

    Full Text Available Penguins are major consumers in the southern oceans although quantification of this has been problematic. One suggestion proposes the use of points of inflection in diving profiles ('wiggles' for this, a method that has been validated for the estimation of prey consumption by Magellanic penguins (Spheniscus magellanicus by Simeone and Wilson (2003. Following them, we used wiggles from 31 depth logger-equipped Magellanic penguins foraging from four Patagonian colonies; Punta Norte (PN, Bahía Bustamente (BB, Puerto Deseado (PD and Puerto San Julián (PSJ, all located in Argentina between 42-49° S, to estimate the prey captured and calculate the catch per unit time (CPUT for birds foraging during the early chick-rearing period. Numbers of prey caught and CPUT were significantly different between colonies. Birds from PD caught the highest number of prey per foraging trip, with CPUT values of 68±19 prey per hour underwater (almost two times greater than for the three remaining colonies. We modeled consumption from these data and calculate that the world Magellanic penguin population consumes about 2 million tons of prey per year. Possible errors in this calculation are discussed. Despite this, the analysis of wiggles seems a powerful and simple tool to begin to quantify prey consumption by Magellanic penguins, allowing comparison between different breeding sites. The total number of wiggles and/or CPUT do not reflect, by themselves, the availability of food for each colony, as the number of prey consumed by foraging trip is strongly associated with the energy content and wet mass of each colony-specific 'prey type'. Individuals consuming more profitable prey could be optimizing the time spent underwater, thereby optimizing the energy expenditure associated with the dives.

  14. Effect of sublethal levels of ionizing radiation on a predator-prey interaction

    International Nuclear Information System (INIS)

    Chee, P.C.

    1976-01-01

    The predator-prey interaction studied was that between the largemouth bass (Micropterus salmoides) and the fathead minnow (Pimephales promelas) in an artificial test environment. Experiments were first conducted to determine the 50% lethal dose at 30 days of the minnow. Three different dose rates were used to test the effect of dose rate on the 50% lethal dose value. After the 50% lethal dose was determined the predator-prey interaction experiment was conducted using 30% of the 50% lethal dose as the highest radiation dose, this dose being considered the upper limit to sublethal radiation levels. A 4 x 4 Latin square design was chosen for the experiment, with four treatment levels (control plus three radiation levels) and four replicates. In each test 10 prey minnow were offered to one predator bass and the number of prey left after 14 days was the parameter of interest. A predator-prey interaction experiment using a single high level of radiation and two types of controls as conducted to ascertain the ability of the test environment to detect changes in the predator-prey interaction. The two types of controls were irradiated prey not exposed to predation and non-irradiated prey exposed to predation. An experiment was also conducted to test the correlation between the physical activity patterns of minnow and different doses of radiation. At a dose rate of 37.8 rad/min the 50% lethal dose at 30 days for minnow was found to be 2650 rad. It was found that dose rate had a strong influence on the 50% lethal dose. In the predator-prey interaction test it was found that the 14-day survival rate of prey was unaffected by sublethal levels of ionizing radiation. No significant correlation was detected between the physical activity patterns of minnow and radiation dose

  15. Prey capture by the crab spider Misumena calycina (Araneae: Thomisidae).

    Science.gov (United States)

    Morse, Douglass H

    1979-01-01

    Crab spiders Misumena calycina (L.) in pasture rose Rosa carolina flowers regularly attacked bumble bees, smaller bees, and syrphid flies that visited these flowers. Attacks reached a maximum rate of over 20/h during mid morning, but only 1.6% of the most important prey item, bumble bees, were captured. The next most important food source, the most frequently taken item, syrphid flies Toxomerus marginatus (Say), were captured in 39% of the attempts. Since these flies have a biomass only 1/60th that of bumble bees, they comprised a much less important food source than did bumble bees. Spiders would obtain over 7% more food by specializing on bumble bees than by attacking all insect visitors, and as much as 20% more food at certain times of the day. However, they did not show a tendency to specialize at any time.

  16. Baleen whales and their prey in a coastal environment

    Science.gov (United States)

    Piatt, John F.; Methven, David A.; Burger, Alan E.; McLagan, Ruth L.; Mercer, Vicki; Creelman, Elizabeth

    1989-01-01

    Patterns of abundance of humpback (Megaptera novaeangliae), fin (Balaenoptera physalus), and minke (Balaenoptera acutorostrata) whales are described in relation to the abundance of their primary prey, capelin (Mallotus villosus), during 1982–1985 at Witless Bay, Newfoundland. The abundance ratio of the three whale species was 10:1:3.5, respectively. Abundance of all whale species was strongly correlated with abundance of capelin through each season and between years. Capelin abundance accounted for 63% of the variation in whale numbers in 1983 and 1984, while environmental parameters (e.g., water temperatures) accounted for little variance. The amount of capelin consumed by whales was small (< 2%) compared with the amount available. All three species overlapped temporally at Witless Bay, but spatial overlap was reduced as fins occurred primarily offshore, minkes primarily inshore, and humpbacks in bay habitats of intermediate depth.

  17. Born Knowing: Tentacled Snakes Innately Predict Future Prey Behavior

    Science.gov (United States)

    Catania, Kenneth C.

    2010-01-01

    Background Aquatic tentacled snakes (Erpeton tentaculatus) can take advantage of their prey's escape response by startling fish with their body before striking. The feint usually startles fish toward the snake's approaching jaws. But when fish are oriented at a right angle to the jaws, the C-start escape response translates fish parallel to the snake's head. To exploit this latter response, snakes must predict the future location of the fish. Adult snakes can make this prediction. Is it learned, or are tentacled snakes born able to predict future fish behavior? Methods and Findings Laboratory-born, naïve snakes were investigated as they struck at fish. Trials were recorded at 250 or 500 frames per second. To prevent learning, snakes were placed in a water container with a clear transparency sheet or glass bottom. The chamber was placed over a channel in a separate aquarium with fish below. Thus snakes could see and strike at fish, without contact. The snake's body feint elicited C-starts in the fish below the transparency sheet, allowing strike accuracy to be quantified in relationship to the C-starts. When fish were oriented at a right angle to the jaws, naïve snakes biased their strikes to the future location of the escaping fish's head, such that the snake's jaws and the fish's translating head usually converged. Several different types of predictive strikes were observed. Conclusions The results show that some predators have adapted their nervous systems to directly compensate for the future behavior of prey in a sensory realm that usually requires learning. Instead of behavior selected during their lifetime, newborn tentacled snakes exhibit behavior that has been selected on a different scale—over many generations. Counter adaptations in fish are not expected, as tentacled snakes are rare predators exploiting fish responses that are usually adaptive. PMID:20585384

  18. Ineffective crypsis in a crab spider: a prey community perspective.

    Science.gov (United States)

    Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

    2010-03-07

    Cryptic coloration is assumed to be beneficial to predators because of an increased encounter rate with unwary prey. This hypothesis is, however, very rarely, if ever, studied in the field. The aim of this study was to quantify the encounter rate and capture success of an ambush predator, in the field, as a function of its level of colour-matching with the background. We used the crab spider Misumena vatia, which varies its body colour and can thereby match the colour of the flower it hunts upon. We carried out a manipulative field experiment using a complete factorial design resulting in six different colour combinations of crab spiders and flowers differing in their degree of colour-matching. A rich and diverse set of naturally occurring insects visited the flowers while we continuously video-recorded the spider's foraging activity. This enabled us to test the crypsis, the spider avoidance and the flower visitor attraction hypotheses, all three supported by previous studies. Flower visitors of different groups either avoided crab spiders independent of colour-matching, such as solitary bees and syrphid flies, or ignored them, such as bumble-bees and honeybees. Moreover, colour-matched spiders did not have a higher encounter rate and capture success compared to the visually apparent ones. Thus, our results support the spider avoidance hypothesis, reject the two other hypotheses and uncovered a fourth behaviour: indifference to predators. Because flower visitors reacted differently, a community approach is mandatory in order to understand the function of background colour-matching in generalist predators. We discuss our results in relation to the size and sociality of the prey and in relation to the functional significance of colour change in this predator.

  19. Interactive effects of prey and weather on golden eagle reproduction

    Science.gov (United States)

    Steenhof, Karen; Kochert, Michael N.; McDonald, T.L.

    1997-01-01

    1. The reproduction of the golden eagle Aquila chrysaetos was studied in southwestern Idaho for 23 years, and the relationship between eagle reproduction and jackrabbit Lepus californicus abundance, weather factors, and their interactions, was modelled using general linear models. Backward elimination procedures were used to arrive at parsimonious models.2. The number of golden eagle pairs occupying nesting territories each year showed a significant decline through time that was unrelated to either annual rabbit abundance or winter severity. However, eagle hatching dates were significantly related to both winter severity and jackrabbit abundance. Eagles hatched earlier when jackrabbits were abundant, and they hatched later after severe winters.3. Jackrabbit abundance influenced the proportion of pairs that laid eggs, the proportion of pairs that were successful, mean brood size at fledging, and the number of young fledged per pair. Weather interacted with prey to influence eagle reproductive rates.4. Both jackrabbit abundance and winter severity were important in predicting the percentage of eagle pairs that laid eggs. Percentage laying was related positively to jackrabbit abundance and inversely related to winter severity.5. The variables most useful in predicting percentage of laying pairs successful were rabbit abundance and the number of extremely hot days during brood-rearing. The number of hot days and rabbit abundance were also significant in a model predicting eagle brood size at fledging. Both success and brood size were positively related to jackrabbit abundance and inversely related to the frequency of hot days in spring.6. Eagle reproduction was limited by rabbit abundance during approximately twothirds of the years studied. Weather influenced how severely eagle reproduction declined in those years.7. This study demonstrates that prey and weather can interact to limit a large raptor population's productivity. Smaller raptors could be affected more

  20. Detectability matters: conspicuous nestling mouth colours make prey transfer easier for parents in a cavity nesting bird.

    Science.gov (United States)

    Dugas, Matthew B

    2015-11-01

    An often underappreciated function of signals is to notify receivers of the presence and position of senders. The colours that ornament the mouthparts of nestling birds, for example, have been hypothesized to evolve via selective pressure generated by parents' inability to efficiently detect and feed nestlings without such visually conspicuous targets. This proposed mechanism has primarily been evaluated with comparative studies and experimental tests for parental allocation bias, leaving untested the central assumption of this detectability hypothesis, that provisioning offspring is a visually challenging task for avian parents and conspicuous mouths help. To test this assumption, I manipulated the mouths of nestling house sparrows to appear minimally and maximally conspicuous, and quantified prey transfer difficulty as the total duration of a feeding event and the number of transfer attempts required. Prey transfer to inconspicuous nestlings was, as predicted, more difficult. While this suggests that detectability constraints could shape nestling mouth colour evolution, even minimally conspicuous nestlings were not prohibitively difficult for parents to feed, indicating that a more nuanced explanation for interspecific diversity in this trait is needed. © 2015 The Author(s).

  1. Prey diversity is affected by climate and differs between age classes in the Red-backed Shrike (Lanius collurio)

    DEFF Research Database (Denmark)

    Pedersen, Lykke; Geertsma, Marten; Tøttrup, Anders P.

    2012-01-01

    -backed Shrike (Lanius collurio) populations in Denmark, based onmore than 11,000 prey items covering seven years.We found a negative correlation between prey diversity and temperature, indicating that Red-backed Shrikes feed on preferred prey items in warmer summers (low diversity)while forced to feed...

  2. The curse of the prey: Sarcoptes mite molecular analysis reveals potential prey-to-predator parasitic infestation in wild animals from Masai Mara, Kenya

    Directory of Open Access Journals (Sweden)

    Soriguer Ramón C

    2011-10-01

    Full Text Available Abstract Background Recently, there have been attempts to understand the molecular epidemiology of Sarcoptes scabiei, to evaluate the gene flow between isolates of S. scabiei from different hosts and geographic regions. However, to our knowledge, a molecular study has not been carried out to assess the molecular diversity and gene flow of Sarcoptes mite in a predator/prey ecosystem. Results Our study revealed an absence of gene flow between the two herbivore (Thomson's gazelle and wildebeest- and between the two carnivore (lion and cheetah-derived Sarcoptes populations from Masai Mara (Kenya, which is in discrepancy with the host-taxon law described for wild animals in Europe. Lion- and wildebeest-derived Sarcoptes mite populations were similar yet different from the Thomson's gazelle-derived Sarcoptes population. This could be attributed to Sarcoptes cross-infestation from wildebeest ("favourite prey" of the lion, but not from Thomson's gazelle. The cheetah-derived Sarcoptes population had different subpopulations: one is cheetah-private, one similar to the wildebeest- and lion-derived Sarcoptes populations, and another similar to the Thomson's gazelle-derived Sarcoptes mite population, where both wildebeest and Thomson's gazelle are "favourite preys" for the cheetah. Conclusions In a predator/prey ecosystem, like Masai Mara in Kenya, it seems that Sarcoptes infestation in wild animals is prey-to-predator-wise, depending on the predator's "favourite prey". More studies on the lion and cheetah diet and behaviour could be of great help to clarify the addressed hypotheses. This study could have further ramification in the epidemiological studies and the monitoring protocols of the neglected Sarcoptes mite in predator/prey ecosystems.

  3. Capabilities of infrared weld monitor

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, P.G.; Keske, J.S.; Leong, K.H.; Kornecki, G.

    1997-11-01

    A non-obtrusive pre-aligned, solid-state device has been developed to monitor the primary infrared emissions during laser welding. The weld monitor output is a 100-1000 mV signal that depends on the beam power and weld characteristics. The DC level of this signal is related to weld penetration, while AC portions of the output can be correlated with surface irregularities and part misalignment or contamination. Changes in DC behavior are also noted for both full and deep penetration welds. Full penetration welds are signified by an abrupt reduction in the weld monitor output. Bead on plate welds were made on steel, aluminum, and magnesium with both a CW CO{sub 2} laser and a pulsed Nd:YAG laser to explore the relationships between the weld characteristics and the weld monitor output.

  4. Prey life-history and bioenergetic responses across a predation gradient.

    Science.gov (United States)

    Rennie, M D; Purchase, C F; Shuter, B J; Collins, N C; Abrams, P A; Morgan, G E

    2010-10-01

    To evaluate the importance of non-consumptive effects of predators on prey life histories under natural conditions, an index of predator abundance was developed for naturally occurring populations of a common prey fish, the yellow perch Perca flavescens, and compared to life-history variables and rates of prey energy acquisition and allocation as estimated from mass balance models. The predation index was positively related to maximum size and size at maturity in both male and female P. flavescens, but not with life span or reproductive investment. The predation index was positively related to size-adjusted specific growth rates and growth efficiencies but negatively related to model estimates of size-adjusted specific consumption and activity rates in both vulnerable (small) and invulnerable (large) size classes of P. flavescens. These observations suggest a trade-off between growth and activity rates, mediated by reduced activity in response to increasing predator densities. Lower growth rates and growth efficiencies in populations with fewer predators, despite increased consumption suggests either 1) a reduction in prey resources at lower predator densities or 2) an intrinsic cost of rapid prey growth that makes it unfavourable unless offset by a perceived threat of predation. This study provides evidence of trade-offs between growth and activity rates induced by predation risk in natural prey fish populations and illustrates how behavioural modification induced through predation can shape the life histories of prey fish species. © 2010 The Authors. Journal compilation © 2010 The Fisheries Society of the British Isles.

  5. The predatory mite Phytoseiulus persimilis adjusts patch-leaving to own and progeny prey needs.

    Science.gov (United States)

    Vanas, V; Enigl, M; Walzer, A; Schausberger, P

    2006-01-01

    Integration of optimal foraging and optimal oviposition theories suggests that predator females should adjust patch leaving to own and progeny prey needs to maximize current and future reproductive success. We tested this hypothesis in the predatory mite Phytoseiulus persimilis and its patchily distributed prey, the two-spotted spider mite Tetranychus urticae. In three separate experiments we assessed (1) the minimum number of prey needed to complete juvenile development, (2) the minimum number of prey needed to produce an egg, and (3) the ratio between eggs laid and spider mites left when a gravid P. persimilis female leaves a patch. Experiments (1) and (2) were the pre-requirements to assess the fitness costs associated with staying or leaving a prey patch. Immature P. persimilis needed at least 7 and on average 14+/-3.6 (SD) T. urticae eggs to reach adulthood. Gravid females needed at least 5 and on average 8.5+/-3.1 (SD) T. urticae eggs to produce an egg. Most females left the initial patch before spider mite extinction, leaving prey for progeny to develop to adulthood. Females placed in a low density patch left 5.6+/-6.1 (SD) eggs per egg laid, whereas those placed in a high density patch left 15.8+/-13.7 (SD) eggs per egg laid. The three experiments in concert suggest that gravid P. persimilis females are able to balance the trade off between optimal foraging and optimal oviposition and adjust patch-leaving to own and progeny prey needs.

  6. Plant architecture and prey distribution influence foraging behavior of the predatory mite Phytoseiulus persimilis (Acari: Phytoseiidae).

    Science.gov (United States)

    Gontijo, Lessando M; Nechols, James R; Margolies, David C; Cloyd, Raymond A

    2012-01-01

    The arrangement, number, and size of plant parts may influence predator foraging behavior, either directly, by altering the rate or pattern of predator movement, or, indirectly, by affecting the distribution and abundance of prey. We report on the effects of both plant architecture and prey distribution on foraging by the predatory mite, Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae), on cucumber (Cucumis sativus L.). Plants differed in leaf number (2- or 6-leafed), and there were associated differences in leaf size, plant height, and relative proportions of plant parts; but all had the same total surface area. The prey, the twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae), were distributed either on the basal leaf or on all leaves. The effect of plant architecture on predator foraging behavior varied depending on prey distribution. The dimensions of individual plant parts affected time allocated to moving and feeding, but they did not appear to influence the frequency with which predators moved among different plant parts. Overall, P. persimilis moved less, and fed upon prey longer, on 6-leafed plants with prey on all leaves than on plants representing other treatment combinations. Our findings suggest that both plant architecture and pattern of prey distribution should be considered, along with other factors such as herbivore-induced plant volatiles, in augmentative biological control programs.

  7. Adaptive evolution of defense ability leads to diversification of prey species.

    Science.gov (United States)

    Zu, Jian; Wang, Jinliang; Du, Jianqiang

    2014-06-01

    In this paper, by using the adaptive dynamics approach, we investigate how the adaptive evolution of defense ability promotes the diversity of prey species in an initial one-prey-two-predator community. We assume that the prey species can evolve to a safer strategy such that it can reduce the predation risk, but a prey with a high defense ability for one predator may have a low defense ability for the other and vice versa. First, by using the method of critical function analysis, we find that if the trade-off is convex in the vicinity of the evolutionarily singular strategy, then this singular strategy is a continuously stable strategy. However, if the trade-off is weakly concave near the singular strategy and the competition between the two predators is relatively weak, then the singular strategy may be an evolutionary branching point. Second, we find that after the branching has occurred in the prey strategy, if the trade-off curve is globally concave, then the prey species might eventually evolve into two specialists, each caught by only one predator species. However, if the trade-off curve is convex-concave-convex, the prey species might eventually branch into two partial specialists, each being caught by both of the two predators and they can stably coexist on the much longer evolutionary timescale.

  8. Cheetahs, Acinonyx jubatus, balance turn capacity with pace when chasing prey

    Science.gov (United States)

    Wilson, John W.; Mills, Michael G. L.; Wilson, Rory P.; Peters, Gerrit; Mills, Margaret E. J.; Speakman, John R.; Durant, Sarah M.; Bennett, Nigel C.; Marks, Nikki J.; Scantlebury, Michael

    2013-01-01

    Predator–prey interactions are fundamental in the evolution and structure of ecological communities. Our understanding, however, of the strategies used in pursuit and evasion remains limited. Here, we report on the hunting dynamics of the world's fastest land animal, the cheetah, Acinonyx jubatus. Using miniaturized data loggers, we recorded fine-scale movement, speed and acceleration of free-ranging cheetahs to measure how hunting dynamics relate to chasing different sized prey. Cheetahs attained hunting speeds of up to 18.94 m s−1 and accelerated up to 7.5 m s−2 with greatest angular velocities achieved during the terminal phase of the hunt. The interplay between forward and lateral acceleration during chases showed that the total forces involved in speed changes and turning were approximately constant over time but varied with prey type. Thus, rather than a simple maximum speed chase, cheetahs first accelerate to decrease the distance to their prey, before reducing speed 5–8 s from the end of the hunt, so as to facilitate rapid turns to match prey escape tactics, varying the precise strategy according to prey species. Predator and prey thus pit a fine balance of speed against manoeuvring capability in a race for survival. PMID:24004493

  9. Relative availability of natural prey versus livestock predicts landscape suitability for cheetahs Acinonyx jubatus in Botswana

    Science.gov (United States)

    Winterbach, Christiaan W.; Boast, Lorraine K.; Klein, Rebecca; Somers, Michael J.

    2015-01-01

    Prey availability and human-carnivore conflict are strong determinants that govern the spatial distribution and abundance of large carnivore species and determine the suitability of areas for their conservation. For wide-ranging large carnivores such as cheetahs (Acinonyx jubatus), additional conservation areas beyond protected area boundaries are crucial to effectively conserve them both inside and outside protected areas. Although cheetahs prefer preying on wild prey, they also cause conflict with people by predating on especially small livestock. We investigated whether the distribution of cheetahs’ preferred prey and small livestock biomass could be used to explore the potential suitability of agricultural areas in Botswana for the long-term persistence of its cheetah population. We found it gave a good point of departure for identifying priority areas for land management, the threat to connectivity between cheetah populations, and areas where the reduction and mitigation of human-cheetah conflict is critical. Our analysis showed the existence of a wide prey base for cheetahs across large parts of Botswana’s agricultural areas, which provide additional large areas with high conservation potential. Twenty percent of wild prey biomass appears to be the critical point to distinguish between high and low probable levels of human-cheetah conflict. We identified focal areas in the agricultural zones where restoring wild prey numbers in concurrence with effective human-cheetah conflict mitigation efforts are the most immediate conservation strategies needed to maintain Botswana’s still large and contiguous cheetah population. PMID:26213646

  10. Global warming alters sound transmission: differential impact on the prey detection ability of echolocating bats

    Science.gov (United States)

    Luo, Jinhong; Koselj, Klemen; Zsebők, Sándor; Siemers, Björn M.; Goerlitz, Holger R.

    2014-01-01

    Climate change impacts the biogeography and phenology of plants and animals, yet the underlying mechanisms are little known. Here, we present a functional link between rising temperature and the prey detection ability of echolocating bats. The maximum distance for echo-based prey detection is physically determined by sound attenuation. Attenuation is more pronounced for high-frequency sound, such as echolocation, and is a nonlinear function of both call frequency and ambient temperature. Hence, the prey detection ability, and thus possibly the foraging efficiency, of echolocating bats and susceptible to rising temperatures through climate change. Using present-day climate data and projected temperature rises, we modelled this effect for the entire range of bat call frequencies and climate zones around the globe. We show that depending on call frequency, the prey detection volume of bats will either decrease or increase: species calling above a crossover frequency will lose and species emitting lower frequencies will gain prey detection volume, with crossover frequency and magnitude depending on the local climatic conditions. Within local species assemblages, this may cause a change in community composition. Global warming can thus directly affect the prey detection ability of individual bats and indirectly their interspecific interactions with competitors and prey. PMID:24335559

  11. Global warming alters sound transmission: differential impact on the prey detection ability of echolocating bats.

    Science.gov (United States)

    Luo, Jinhong; Koselj, Klemen; Zsebok, Sándor; Siemers, Björn M; Goerlitz, Holger R

    2014-02-06

    Climate change impacts the biogeography and phenology of plants and animals, yet the underlying mechanisms are little known. Here, we present a functional link between rising temperature and the prey detection ability of echolocating bats. The maximum distance for echo-based prey detection is physically determined by sound attenuation. Attenuation is more pronounced for high-frequency sound, such as echolocation, and is a nonlinear function of both call frequency and ambient temperature. Hence, the prey detection ability, and thus possibly the foraging efficiency, of echolocating bats and susceptible to rising temperatures through climate change. Using present-day climate data and projected temperature rises, we modelled this effect for the entire range of bat call frequencies and climate zones around the globe. We show that depending on call frequency, the prey detection volume of bats will either decrease or increase: species calling above a crossover frequency will lose and species emitting lower frequencies will gain prey detection volume, with crossover frequency and magnitude depending on the local climatic conditions. Within local species assemblages, this may cause a change in community composition. Global warming can thus directly affect the prey detection ability of individual bats and indirectly their interspecific interactions with competitors and prey.

  12. Musculoskeletal anatomy of the Eurasian lynx, Lynx lynx (Carnivora: Felidae) forelimb: Adaptations to capture large prey?

    Science.gov (United States)

    Viranta, Suvi; Lommi, Hanna; Holmala, Katja; Laakkonen, Juha

    2016-06-01

    Mammalian carnivores adhere to two different feeding strategies relative to their body masses. Large carnivores prey on animals that are the same size or larger than themselves, whereas small carnivores prey on smaller vertebrates and invertebrates. The Eurasian lynx (Lynx lynx) falls in between these two categories. Lynx descend from larger forms that were probably large prey specialists, but during the Pleistocene became predators of small prey. The modern Eurasian lynx may be an evolutionary reversal toward specializing in large prey again. We hypothesized that the musculoskeletal anatomy of lynx should show traits for catching large prey. To test our hypothesis, we dissected the forelimb muscles of six Eurasian lynx individuals and compared our findings to results published for other felids. We measured the bones and compared their dimensions to the published material. Our material displayed a well-developed pectoral girdle musculature with some uniquely extensive muscle attachments. The upper arm musculature resembled that of the pantherine felids and probably the extinct sabertooths, and also the muscles responsible for supination and pronation were similar to those in large cats. The muscles controlling the pollex were well-developed. However, skeletal indices were similar to those of small prey predators. Our findings show that lynx possess the topographic pattern of muscle origin and insertion like in large felids. J. Morphol. 277:753-765, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  13. Invasive lionfish had no measurable effect on prey fish community structure across the Belizean Barrier Reef.

    Science.gov (United States)

    Hackerott, Serena; Valdivia, Abel; Cox, Courtney E; Silbiger, Nyssa J; Bruno, John F

    2017-01-01

    Invasive lionfish are assumed to significantly affect Caribbean reef fish communities. However, evidence of lionfish effects on native reef fishes is based on uncontrolled observational studies or small-scale, unrepresentative experiments, with findings ranging from no effect to large effects on prey density and richness. Moreover, whether lionfish affect populations and communities of native reef fishes at larger, management-relevant scales is unknown. The purpose of this study was to assess the effects of lionfish on coral reef prey fish communities in a natural complex reef system. We quantified lionfish and the density, richness, and composition of native prey fishes (0-10 cm total length) at sixteen reefs along ∼250 km of the Belize Barrier Reef from 2009 to 2013. Lionfish invaded our study sites during this four-year longitudinal study, thus our sampling included fish community structure before and after our sites were invaded, i.e., we employed a modified BACI design. We found no evidence that lionfish measurably affected the density, richness, or composition of prey fishes. It is possible that higher lionfish densities are necessary to detect an effect of lionfish on prey populations at this relatively large spatial scale. Alternatively, negative effects of lionfish on prey could be small, essentially undetectable, and ecologically insignificant at our study sites. Other factors that influence the dynamics of reef fish populations including reef complexity, resource availability, recruitment, predation, and fishing could swamp any effects of lionfish on prey populations.

  14. Invasive lionfish had no measurable effect on prey fish community structure across the Belizean Barrier Reef

    Directory of Open Access Journals (Sweden)

    Serena Hackerott

    2017-05-01

    Full Text Available Invasive lionfish are assumed to significantly affect Caribbean reef fish communities. However, evidence of lionfish effects on native reef fishes is based on uncontrolled observational studies or small-scale, unrepresentative experiments, with findings ranging from no effect to large effects on prey density and richness. Moreover, whether lionfish affect populations and communities of native reef fishes at larger, management-relevant scales is unknown. The purpose of this study was to assess the effects of lionfish on coral reef prey fish communities in a natural complex reef system. We quantified lionfish and the density, richness, and composition of native prey fishes (0–10 cm total length at sixteen reefs along ∼250 km of the Belize Barrier Reef from 2009 to 2013. Lionfish invaded our study sites during this four-year longitudinal study, thus our sampling included fish community structure before and after our sites were invaded, i.e., we employed a modified BACI design. We found no evidence that lionfish measurably affected the density, richness, or composition of prey fishes. It is possible that higher lionfish densities are necessary to detect an effect of lionfish on prey populations at this relatively large spatial scale. Alternatively, negative effects of lionfish on prey could be small, essentially undetectable, and ecologically insignificant at our study sites. Other factors that influence the dynamics of reef fish populations including reef complexity, resource availability, recruitment, predation, and fishing could swamp any effects of lionfish on prey populations.

  15. Relative availability of natural prey versus livestock predicts landscape suitability for cheetahs Acinonyx jubatus in Botswana.

    Science.gov (United States)

    Winterbach, Hanlie E K; Winterbach, Christiaan W; Boast, Lorraine K; Klein, Rebecca; Somers, Michael J

    2015-01-01

    Prey availability and human-carnivore conflict are strong determinants that govern the spatial distribution and abundance of large carnivore species and determine the suitability of areas for their conservation. For wide-ranging large carnivores such as cheetahs (Acinonyx jubatus), additional conservation areas beyond protected area boundaries are crucial to effectively conserve them both inside and outside protected areas. Although cheetahs prefer preying on wild prey, they also cause conflict with people by predating on especially small livestock. We investigated whether the distribution of cheetahs' preferred prey and small livestock biomass could be used to explore the potential suitability of agricultural areas in Botswana for the long-term persistence of its cheetah population. We found it gave a good point of departure for identifying priority areas for land management, the threat to connectivity between cheetah populations, and areas where the reduction and mitigation of human-cheetah conflict is critical. Our analysis showed the existence of a wide prey base for cheetahs across large parts of Botswana's agricultural areas, which provide additional large areas with high conservation potential. Twenty percent of wild prey biomass appears to be the critical point to distinguish between high and low probable levels of human-cheetah conflict. We identified focal areas in the agricultural zones where restoring wild prey numbers in concurrence with effective human-cheetah conflict mitigation efforts are the most immediate conservation strategies needed to maintain Botswana's still large and contiguous cheetah population.

  16. Relative availability of natural prey versus livestock predicts landscape suitability for cheetahs Acinonyx jubatus in Botswana

    Directory of Open Access Journals (Sweden)

    Hanlie E.K. Winterbach

    2015-07-01

    Full Text Available Prey availability and human-carnivore conflict are strong determinants that govern the spatial distribution and abundance of large carnivore species and determine the suitability of areas for their conservation. For wide-ranging large carnivores such as cheetahs (Acinonyx jubatus, additional conservation areas beyond protected area boundaries are crucial to effectively conserve them both inside and outside protected areas. Although cheetahs prefer preying on wild prey, they also cause conflict with people by predating on especially small livestock. We investigated whether the distribution of cheetahs’ preferred prey and small livestock biomass could be used to explore the potential suitability of agricultural areas in Botswana for the long-term persistence of its cheetah population. We found it gave a good point of departure for identifying priority areas for land management, the threat to connectivity between cheetah populations, and areas where the reduction and mitigation of human-cheetah conflict is critical. Our analysis showed the existence of a wide prey base for cheetahs across large parts of Botswana’s agricultural areas, which provide additional large areas with high conservation potential. Twenty percent of wild prey biomass appears to be the critical point to distinguish between high and low probable levels of human-cheetah conflict. We identified focal areas in the agricultural zones where restoring wild prey numbers in concurrence with effective human-cheetah conflict mitigation efforts are the most immediate conservation strategies needed to maintain Botswana’s still large and contiguous cheetah population.

  17. Cheetahs, Acinonyx jubatus, balance turn capacity with pace when chasing prey.

    Science.gov (United States)

    Wilson, John W; Mills, Michael G L; Wilson, Rory P; Peters, Gerrit; Mills, Margaret E J; Speakman, John R; Durant, Sarah M; Bennett, Nigel C; Marks, Nikki J; Scantlebury, Michael

    2013-10-23

    Predator-prey interactions are fundamental in the evolution and structure of ecological communities. Our understanding, however, of the strategies used in pursuit and evasion remains limited. Here, we report on the hunting dynamics of the world's fastest land animal, the cheetah, Acinonyx jubatus. Using miniaturized data loggers, we recorded fine-scale movement, speed and acceleration of free-ranging cheetahs to measure how hunting dynamics relate to chasing different sized prey. Cheetahs attained hunting speeds of up to 18.94 m s(-1) and accelerated up to 7.5 m s(-2) with greatest angular velocities achieved during the terminal phase of the hunt. The interplay between forward and lateral acceleration during chases showed that the total forces involved in speed changes and turning were approximately constant over time but varied with prey type. Thus, rather than a simple maximum speed chase, cheetahs first accelerate to decrease the distance to their prey, before reducing speed 5-8 s from the end of the hunt, so as to facilitate rapid turns to match prey escape tactics, varying the precise strategy according to prey species. Predator and prey thus pit a fine balance of speed against manoeuvring capability in a race for survival.

  18. Impact of marine reserve on maximum sustainable yield in a traditional prey-predator system

    Science.gov (United States)

    Paul, Prosenjit; Kar, T. K.; Ghorai, Abhijit

    2018-01-01

    Multispecies fisheries management requires managers to consider the impact of fishing activities on several species as fishing impacts both targeted and non-targeted species directly or indirectly in several ways. The intended goal of traditional fisheries management is to achieve maximum sustainable yield (MSY) from the targeted species, which on many occasions affect the targeted species as well as the entire ecosystem. Marine reserves are often acclaimed as the marine ecosystem management tool. Few attempts have been made to generalize the ecological effects of marine reserve on MSY policy. We examine here how MSY and population level in a prey-predator system are affected by the low, medium and high reserve size under different possible scenarios. Our simulation works shows that low reserve area, the value of MSY for prey exploitation is maximum when both prey and predator species have fast movement rate. For medium reserve size, our analysis revealed that the maximum value of MSY for prey exploitation is obtained when prey population has fast movement rate and predator population has slow movement rate. For high reserve area, the maximum value of MSY for prey's exploitation is very low compared to the maximum value of MSY for prey's exploitation in case of low and medium reserve. On the other hand, for low and medium reserve area, MSY for predator exploitation is maximum when both the species have fast movement rate.

  19. Infrared microscope inspection apparatus

    Science.gov (United States)

    Forman, Steven E.; Caunt, James W.

    1985-02-26

    Apparatus and system for inspecting infrared transparents, such as an array of photovoltaic modules containing silicon solar cells, includes an infrared microscope, at least three sources of infrared light placed around and having their axes intersect the center of the object field and means for sending the reflected light through the microscope. The apparatus is adapted to be mounted on an X-Y translator positioned adjacent the object surface.

  20. Far infrared supplement: Catalog of infrared observations, second edition

    International Nuclear Information System (INIS)

    Gezari, D.Y.; Schmitz, M.; Mead, J.M.

    1988-08-01

    The Far Infrared Supplement: Catalog of Infrared Observations summarizes all infrared astronomical observations at far infrared wavelengths (5 to 1000 microns) published in the scientific literature from 1965 through 1986. The Supplement list contain 25 percent of the observations in the full Catalog of Infrared Observations (CIO), and essentially eliminates most visible stars from the listings. The Supplement is thus more compact than the main catalog, and is intended for easy reference during astronomical observations. The Far Infrared Supplement (2nd Edition) includes the Index of Infrared Source Positions and the Bibliography of Infrared Astronomy for the subset of far infrared observations listed

  1. Tokamak plasma current disruption infrared control system

    International Nuclear Information System (INIS)

    Kugel, H.W.; Ulrickson, M.

    1987-01-01

    This patent describes a device for magnetically confining a plasma driven by a plasma current and contained within a toroidal vacuum chamber, the device having an inner toroidal limiter on an inside wall of the vacuum chamber and an arrangement for the rapid prediction and control in real time of a major plasma disruption. The arrangement is described which includes: scanning means sensitive to infrared radiation emanating from within the vacuum chamber, the infrared radiation indicating the temperature along a vertical profile of the inner toroidal limiter. The scanning means is arranged to observe the infrared radiation and to produce in response thereto an electrical scanning output signal representative of a time scan of temperature along the vertical profile; detection means for analyzing the scanning output signal to detect a first peaked temperature excursion occurring along the profile of the inner toroidal limiter, and to produce a detection output signal in repsonse thereto, the detection output signal indicating a real time prediction of a subsequent major plasma disruption; and plasma current reduction means for reducing the plasma current driving the plasma, in response to the detection output signal and in anticipation of a subsequent major plasma disruption

  2. Mid-Infrared Lasers

    Data.gov (United States)

    National Aeronautics and Space Administration — Mid infrared solid state lasers for Differential Absorption Lidar (DIAL) systems required for understanding atmospheric chemistry are not available. This program...

  3. Modulation of shark prey capture kinematics in response to sensory deprivation.

    Science.gov (United States)

    Gardiner, Jayne M; Atema, Jelle; Hueter, Robert E; Motta, Philip J

    2017-02-01

    The ability of predators to modulate prey capture in response to the size, location, and behavior of prey is critical to successful feeding on a variety of prey types. Modulating in response to changes in sensory information may be critical to successful foraging in a variety of environments. Three shark species with different feeding morphologies and behaviors were filmed using high-speed videography while capturing live prey: the ram-feeding blacktip shark, the ram-biting bonnethead, and the suction-feeding nurse shark. Sharks were examined intact and after sensory information was blocked (olfaction, vision, mechanoreception, and electroreception, alone and in combination), to elucidate the contribution of the senses to the kinematics of prey capture. In response to sensory deprivation, the blacktip shark demonstrated the greatest amount of modulation, followed by the nurse shark. In the absence of olfaction, blacktip sharks open the jaws slowly, suggestive of less motivation. Without lateral line cues, blacktip sharks capture prey from greater horizontal angles using increased ram. When visual cues are absent, blacktip sharks elevate the head earlier and to a greater degree, allowing them to overcome imprecise position of the prey relative to the mouth, and capture prey using decreased ram, while suction remains unchanged. When visual cues are absent, nurse sharks open the mouth wider, extend the labial cartilages further, and increase suction while simultaneously decreasing ram. Unlike some bony fish, neither species switches feeding modalities (i.e. from ram to suction or vice versa). Bonnetheads failed to open the mouth when electrosensory cues were blocked, but otherwise little to no modulation was found in this species. These results suggest that prey capture may be less plastic in elasmobranchs than in bony fishes, possibly due to anatomical differences, and that the ability to modulate feeding kinematics in response to available sensory information varies

  4. Inferring predator behavior from attack rates on prey-replicas that differ in conspicuousness.

    Directory of Open Access Journals (Sweden)

    Yoel E Stuart

    Full Text Available Behavioral ecologists and evolutionary biologists have long studied how predators respond to prey items novel in color and pattern. Because a predatory response is influenced by both the predator's ability to detect the prey and a post-detection behavioral response, variation among prey types in conspicuousness may confound inference about post-prey-detection predator behavior. That is, a relatively high attack rate on a given prey type may result primarily from enhanced conspicuousness and not predators' direct preference for that prey. Few studies, however, account for such variation in conspicuousness. In a field experiment, we measured predation rates on clay replicas of two aposematic forms of the poison dart frog Dendrobates pumilio, one novel and one familiar, and two cryptic controls. To ask whether predators prefer or avoid a novel aposematic prey form independently of conspicuousness differences among replicas, we first modeled the visual system of a typical avian predator. Then, we used this model to estimate replica contrast against a leaf litter background to test whether variation in contrast alone could explain variation in predator attack rate. We found that absolute predation rates did not differ among color forms. Predation rates relative to conspicuousness did, however, deviate significantly from expectation, suggesting that predators do make post-detection decisions to avoid or attack a given prey type. The direction of this deviation from expectation, though, depended on assumptions we made about how avian predators discriminate objects from the visual background. Our results show that it is important to account for prey conspicuousness when investigating predator behavior and also that existing models of predator visual systems need to be refined.

  5. Food abundance, prey morphology, and diet specialization influence individual sea otter tool use

    Science.gov (United States)

    Fujii, Jessica A.; Ralls, Katherine; Tinker, M. Tim

    2017-01-01

    Sea otters are well-known tool users, employing objects such as rocks or shells to break open invertebrate prey. We used a series of generalized linear mixed effect models to examine observational data on prey capture and tool use from 211 tagged individuals from 5 geographically defined study areas throughout the sea otter’s range in California. Our best supported model was able to explain 75% of the variation in the frequency of tool use by individual sea otters with only ecological and demographic variables. In one study area, where sea otter food resources were abundant, all individuals had similar diets focusing on preferred prey items and used tools at low to moderate frequencies (4–38% of prey captures). In the remaining areas, where sea otters were food-limited, individuals specialized on different subsets of the available prey and had a wider range of average tool-use frequency (0–98% of prey captures). The prevalence of difficult-to-access prey in individual diets was a major predictor of tool use and increased the likelihood of using tools on prey that were not difficult to access as well. Age, sex, and feeding habitat also contributed to the probability of tool use but to a smaller extent. We developed a conceptual model illustrating how food abundance, the prevalence of difficult-to-access prey, and individual diet specialization interacted to determine the likelihood that individual sea otters would use tools and considered the model’s relevance to other tool-using species.

  6. Modelling the dynamics of traits involved in fighting-predators-prey system.

    Science.gov (United States)

    Kooi, B W

    2015-12-01

    We study the dynamics of a predator-prey system where predators fight for captured prey besides searching for and handling (and digestion) of the prey. Fighting for prey is modelled by a continuous time hawk-dove game dynamics where the gain depends on the amount of disputed prey while the costs for fighting is constant per fighting event. The strategy of the predator-population is quantified by a trait being the proportion of the number of predator-individuals playing hawk tactics. The dynamics of the trait is described by two models of adaptation: the replicator dynamics (RD) and the adaptive dynamics (AD). In the RD-approach a variant individual with an adapted trait value changes the population's strategy, and consequently its trait value, only when its payoff is larger than the population average. In the AD-approach successful replacement of the resident population after invasion of a rare variant population with an adapted trait value is a step in a sequence changing the population's strategy, and hence its trait value. The main aim is to compare the consequences of the two adaptation models. In an equilibrium predator-prey system this will lead to convergence to a neutral singular strategy, while in the oscillatory system to a continuous singular strategy where in this endpoint the resident population is not invasible by any variant population. In equilibrium (low prey carrying capacity) RD and AD-approach give the same results, however not always in a periodically oscillating system (high prey carrying-capacity) where the trait is density-dependent. For low costs the predator population is monomorphic (only hawks) while for high costs dimorphic (hawks and doves). These results illustrate that intra-specific trait dynamics matters in predator-prey dynamics.

  7. Relative Preference and Localized Food Affect Predator Space Use and Consumption of Incidental Prey.

    Directory of Open Access Journals (Sweden)

    Tyler E Schartel

    Full Text Available Abundant, localized foods can concentrate predators and their foraging efforts, thus altering both the spatial distribution of predation risk and predator preferences for prey that are encountered incidentally. However, few investigations have quantified the spatial scale over which localized foods affect predator foraging behavior and consumption of incidental prey. In spring 2010, we experimentally tested how point-source foods altered how generalist predators (white-footed mice, Peromyscus leucopus utilized space and depredated two incidental prey items: almonds (Prunus dulcis; highly profitable and maple seeds (Acer saccharum; less profitable. We estimated mouse population densities with trapping webs, quantified mouse consumption rates of these incidental prey items, and measured local mouse activity with track plates. We predicted that 1 mouse activity would be elevated near full feeders, but depressed at intermediate distances from the feeder, 2 consumption of both incidental prey would be high near feeders providing less-preferred food and, 3 consumption of incidental prey would be contingent on predator preference for prey relative to feeders providing more-preferred food. Mouse densities increased significantly from pre- to post-experiment. Mean mouse activity was unexpectedly greatest in control treatments, particularly <15 m from the control (empty feeder. Feeders with highly preferred food (sunflower seeds created localized refuges for incidental prey at intermediate distances (15 to 25m from the feeder. Feeders with less-preferred food (corn generated localized high risk for highly preferred almonds <10 m of the feeder. Our findings highlight the contingent but predictable effects of locally abundant food on risk experienced by incidental prey, which can be positive or negative depending on both spatial proximity and relative preference.

  8. Predator-prey interactions in selected slow and fast developing females of a ladybird, Propylea dissecta.

    Science.gov (United States)

    Siddiqui, Arshi; Omkar; Mishra, Geetanjali

    2015-10-14

    Development rate polymorphism describes the scenario in which individuals exhibit distinct differences in their rate of development resulting in slow and fast developers even from the same clutch of eggs. Previously we showed that in ladybird, Propylea dissecta fast developers have higher foraging and predation rates than slow developers. But correlation between foraging efficacies with reproductive output of female remains unexplored. We selected slow and fast developmental rate for 15 generations in a P. dissecta and assessed female functional response and numerical response by using varying prey biomasses (A. pisum). We evaluated predatory parameters: prey consumption, attack rate, handling time, and the reproductive measures: number of eggs laid, egg, and body biomass conversion efficiencies. Overall, both group of P. dissecta showed increased prey biomasses curvilinear for consumption rate demonstrating the physiological capacity of foraging for food are mutually exclusive behaviors (i.e., Holling's Type-II functional response). Consumption rate and proportion of prey consumed was higher, and prey handling time was shorter, in experimental fast developers. However, prey attack rate was higher in experimental slow developers. The functional response of experimental fast developers got elevated whereas got depressed for control slow-fast developers. Our results suggest that slow developers may perform better at low prey biomass than fast developers due to their high attack rate whereas high density prey may favour fast developers due to their shorter prey handling time and higher consumption rates. This study is first attempt to evaluate predatory responses of experimentally selected lines of slow and fast developers. J. Exp. Zool. 9999A:XX-XX, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  9. Comparing prey composition and prey size delivered to nestlings by great tits, Parus major, and blue tits, Cyanistes caeruleus, in a Mediterranean sclerophyllous mixed forest

    International Nuclear Information System (INIS)

    Navalpotro, H.; Pagani-Nuñez, E.; Hernandez-Gomez, S.; Senar, J.C.

    2016-01-01

    Resource partitioning is a central issue in ecology because it can establish to which point similar species can coexist in the same habitat. Great tits and blue tits have been classical model species in studies of trophic competence. However, most studies on the topic have been conducted at localities where caterpillars are by far the most relevant prey brought to the nestlings. In Mediterranean mixed forests, nevertheless, the abundance of caterpillars is relatively low and it is spiders that play a key role in the diet of great tits, at least for nestlings. The aim of this paper was to study nest food provisioning to establish the degree of diet overlap of these two tit species in a Mediterranean forest. Our results showed that blue tit feeding rates were higher than those of great tits, probably to compensate for the smaller prey delivered to nestlings by blue tits. Blue tits brought more spiders than great tits, while grey tits brought larger prey and more caterpillars. This may be because larger great tits can prey upon larger prey items than blue tits. As a main result, this study supports the view of resource partitioning by great and blue tits in sclerophyllous Mediterranean forest ecosystem. (Author)

  10. Comparing prey composition and prey size delivered to nestlings by great tits, Parus major, and blue tits, Cyanistes caeruleus, in a Mediterranean sclerophyllous mixed forest

    Directory of Open Access Journals (Sweden)

    Navalpotro, H.

    2016-04-01

    Full Text Available Resource partitioning is a central issue in ecology because it can establish to which point similar species can coexist in the same habitat. Great tits and blue tits have been classical model species in studies of trophic competence. However, most studies on the topic have been conducted at localities where caterpillars are by far the most relevant prey brought to the nestlings. In Mediterranean mixed forests, nevertheless, the abundance of caterpillars is relatively low and it is spiders that play a key role in the diet of great tits, at least for nestlings. The aim of this paper was to study nest food provisioning to establish the degree of diet overlap of these two tit species in a Mediterranean forest. Our results showed that blue tit feeding rates were higher than those of great tits, probably to compensate for the smaller prey delivered to nestlings by blue tits. Blue tits brought more spiders than great tits, while grey tits brought larger prey and more caterpillars. This may be because larger great tits can prey upon larger prey items than blue tits. As a main result, this study supports the view of resource partitioning by great and blue tits in sclerophyllous Mediterranean forest ecosystem.

  11. Comparing prey composition and prey size delivered to nestlings by great tits, Parus major, and blue tits, Cyanistes caeruleus, in a Mediterranean sclerophyllous mixed forest

    Energy Technology Data Exchange (ETDEWEB)

    Navalpotro, H.; Pagani-Nuñez, E.; Hernandez-Gomez, S.; Senar, J.C.

    2016-07-01

    Resource partitioning is a central issue in ecology because it can establish to which point similar species can coexist in the same habitat. Great tits and blue tits have been classical model species in studies of trophic competence. However, most studies on the topic have been conducted at localities where caterpillars are by far the most relevant prey brought to the nestlings. In Mediterranean mixed forests, nevertheless, the abundance of caterpillars is relatively low and it is spiders that play a key role in the diet of great tits, at least for nestlings. The aim of this paper was to study nest food provisioning to establish the degree of diet overlap of these two tit species in a Mediterranean forest. Our results showed that blue tit feeding rates were higher than those of great tits, probably to compensate for the smaller prey delivered to nestlings by blue tits. Blue tits brought more spiders than great tits, while grey tits brought larger prey and more caterpillars. This may be because larger great tits can prey upon larger prey items than blue tits. As a main result, this study supports the view of resource partitioning by great and blue tits in sclerophyllous Mediterranean forest ecosystem. (Author)

  12. Survival probability of Baltic larval cod in relation to spatial overlap patterns with their prey obtained from drift model studies

    DEFF Research Database (Denmark)

    Hinrichsen, H.H.; Schmidt, J.O.; Petereit, C.

    2005-01-01

    Temporal mismatch between the occurrence of larvae and their prey potentially affects the spatial overlap and thus the contact rates between predator and prey. This might have important consequences for growth and survival. We performed a case study investigating the influence of circulation......-prey overlap, dependent on the hatching time of cod larvae. By performing model runs for the years 1979-1998 investigated the intra- and interannual variability of potential spatial overlap between predator and prey. Assuming uniform prey distributions, we generally found the overlap to have decreased since...

  13. Pattern formation induced by cross-diffusion in a predator–prey system

    International Nuclear Information System (INIS)

    Sun Guiquan; Jin Zhen; Liu Quanxing; Li Li

    2008-01-01

    This paper considers the Holling–Tanner model for predator–prey with self and cross-diffusion. From the Turing theory, it is believed that there is no Turing pattern formation for the equal self-diffusion coefficients. However, combined with cross-diffusion, it shows that the system will exhibit spotted pattern by both mathematical analysis and numerical simulations. Furthermore, asynchrony of the predator and the prey in the space. The obtained results show that cross-diffusion plays an important role on the pattern formation of the predator–prey system. (general)

  14. Prey exoskeletons influence the course of gastric evacuation in Atlantic cod Gadus morhua

    DEFF Research Database (Denmark)

    Couturier, C. S.; Andersen, N. G.; Audet, C.

    2013-01-01

    species, Pandalus borealis, Pandalus montagui and Eualus macilentus, and the crab Chionoecetes opilio, were evacuated from the stomach at different rates. The duration of all stages increased with increasing ash (and carbonate) content of the fresh prey. Thickness, chemical composition and morphology...... of the prey exoskeleton all affected gastric evacuation: duration of initial delay, overall evacuation rate and a decreased evacuation rate at the end of the process. The power exponential function (PEF), with its shape parameter, described the course of evacuation for these prey types well, especially...

  15. Prey Preferences of the Snow Leopard (Panthera uncia): Regional Diet Specificity Holds Global Significance for Conservation

    OpenAIRE

    Lyngdoh, Salvador; Shrotriya, Shivam; Goyal, Surendra P.; Clements, Hayley; Hayward, Matthew W.; Habib, Bilal

    2014-01-01

    The endangered snow leopard is a large felid that is distributed over 1.83 million km(2) globally. Throughout its range it relies on a limited number of prey species in some of the most inhospitable landscapes on the planet where high rates of human persecution exist for both predator and prey. We reviewed 14 published and 11 unpublished studies pertaining to snow leopard diet throughout its range. We calculated prey consumption in terms of frequency of occurrence and biomass consumed based o...

  16. The nutritional nexus: linking niche, habitat variability and prey composition in a generalist marine predator.

    Science.gov (United States)

    Machovsky-Capuska, Gabriel E; Miller, Mark G R; Silva, Fabiola R O; Amiot, Christophe; Stockin, Karen A; Senior, Alistair M; Schuckard, Rob; Melville, David; Raubenheimer, David

    2018-06-05

    1.Our understanding of the niche concept will remain limited while the quantity and range of different food types eaten remains a dominant proxy for niche breadth, as this does not account for the broad ecological context that governs diet. Linking nutrition, physiology and behaviour are critical to predict the extent to which a species adjusts its nutritional niche breadth at the levels of prey ("prey composition niche", defined as the range of prey compositions eaten), and diet ("realized nutritional niche" is the range of diets composed through feeding on the prey). 2.Here we studied adult-chick rearing Australasian gannets (Morus serrator) to propose an integrative approach using sea surface temperature anomalies (SSTa), geographic location and bathymetry over different years, to explore their relationship with the nutritional composition of prey and diets (i.e., prey composition and nutritional niche breadth), habitat use and foraging behavior. 3.We found that gannets feed on prey that varied widely in their nutritional composition (have a broad prey composition niche), and composed diets from these prey that likewise varied in composition (have a broad realized nutritional niche), suggesting generalism at two levels of macronutrient selection. 4.Across seasons, we established "nutritional landscapes" (hereafter nutriscapes), linking the nutritional content of prey (wet mass protein to-lipid ratio -P:L-) to the most likely geographic area of capture and bathymetry. Nutriscapes varied in their P:L from 6.06 to 15.28, over time, space and bathymetry (0 to 150 m). 5.During warm water events (strong positive SSTa), gannets expanded their foraging habitat, increased their foraging trip duration and consumed prey and diets with low macronutrient content (wet mass proportions of P and L). They were also constrained to the smallest prey composition and realized nutritional niche breadths. 6.Our findings are consistent with previous suggestions that dietary generalism

  17. Using insect traps to increase weaver ant (Oecophylla longinoda) prey capture

    DEFF Research Database (Denmark)

    Lynegaard, Gina; Offenberg, Joachim; Fast, Thora

    2014-01-01

    Weaver ants (Oecophylla spp.) are managed in plantations to control insect pests and are sometimes harvested as a protein rich food source. In both cases, the amount of insect prey caught by the ants is imperative for returns, as more prey leads to more effective biocontrol and to a higher...... by O. longinoda under natural conditions (without traps), potentially increasing to 14% if ants learn to extract all insects. Thus, prey intake may be increased with 5-14% per 3.9 USD invested in traps. These numbers increased to 38 and 78%, respectively, when light was used to attract insects during...

  18. Type of prey influences biology and consumption rate of Orius insidiosus (Say (Hemiptera, Anthocoridae

    Directory of Open Access Journals (Sweden)

    Simone M. Mendes

    2002-01-01

    Full Text Available Generalist predators are capable of consuming different types of prey, and as each prey may have distinct nutritional values, each may have a distinct impact on the biology of the predator. Therefore, the aim of this study was to determine how the consumption of different prey influences certain biological characteristics and the predatory capacity of Orius insidiosus (Say. The investigation was performed in climatic chamber at 25 ±1 ºC, RH 70 ± 10% and fotophase 12. Eggs of Anagasta kuehniella (Zeller, adults of Caliothrips phaseoli (Hood and nymphs of Aphis gossypii Glover were used as prey and were provided daily ad libitum for all the mobile stages of the predator. The results showed that biological parameters of O. insidiosus are affected differently depending on the type of prey ingested. The development time of the nymphal stage was 13.1, 11.23 and 10.25 days for O. insidiosus feeding on eggs of A. kuehniella, nymphs of A. gossypii and adults of C. phaseoli, respectively. Longevity was five times larger for adults fed on eggs of A. kuehniella (56.25 days compared to that of adults that preyed on nymphs of A. gossypii (11.44 days, and four times larger when the prey were adults of C. phaseoli (13.58 days. The consumption of eggs of A. kuehniella by predator females resulted in a shorter pre-oviposition period (3.2 days and a longer oviposition period (44.4 days when compared to the consumption of other types of prey. In addition, fecundity was increased with the consumption of eggs of A. kuehniella (195.25 eggs laid / female when compared to feeding on the other prey, C. phaseoli (70.00 eggs laid / female or A. gossypii (22.50 eggs laid / female. However, the consumption of aphids was larger (148.28 nymphs/ nymphal stage than that of thrips (74.10 thrips / nymphal stage or eggs of A. kuehniella (37.03 eggs /nymphal stage for all of the nymphal stages of the predator. The results indicate that the eggs of A. kuehniella are the type of

  19. Evidence for the Higher Importance of Signal Size Over Body Size in Aposematic Signaling in Insects

    OpenAIRE

    Remmel, Triinu; Tammarub, Toomas

    2011-01-01

    To understand the evolution of warning coloration, it is important to distinguish between different aspects of conspicuous color patterns. As an example, both pattern element size and body size of prey have been shown to enhance the effectiveness of warning signals. However, it is unclear whether the effect of body size is merely a side effect of proportionally increasing pattern elements, or if there is an effect of body size per se. These possibilities were evaluated by offering different s...

  20. Stochastic population dynamics in spatially extended predator-prey systems

    Science.gov (United States)

    Dobramysl, Ulrich; Mobilia, Mauro; Pleimling, Michel; Täuber, Uwe C.

    2018-02-01

    Spatially extended population dynamics models that incorporate demographic noise serve as case studies for the crucial role of fluctuations and correlations in biological systems. Numerical and analytic tools from non-equilibrium statistical physics capture the stochastic kinetics of these complex interacting many-particle systems beyond rate equation approximations. Including spatial structure and stochastic noise in models for predator-prey competition invalidates the neutral Lotka-Volterra population cycles. Stochastic models yield long-lived erratic oscillations stemming from a resonant amplification mechanism. Spatially extended predator-prey systems display noise-stabilized activity fronts that generate persistent correlations. Fluctuation-induced renormalizations of the oscillation parameters can be analyzed perturbatively via a Doi-Peliti field theory mapping of the master equation; related tools allow detailed characterization of extinction pathways. The critical steady-state and non-equilibrium relaxation dynamics at the predator extinction threshold are governed by the directed percolation universality class. Spatial predation rate variability results in more localized clusters, enhancing both competing species’ population densities. Affixing variable interaction rates to individual particles and allowing for trait inheritance subject to mutations induces fast evolutionary dynamics for the rate distributions. Stochastic spatial variants of three-species competition with ‘rock-paper-scissors’ interactions metaphorically describe cyclic dominance. These models illustrate intimate connections between population dynamics and evolutionary game theory, underscore the role of fluctuations to drive populations toward extinction, and demonstrate how space can support species diversity. Two-dimensional cyclic three-species May-Leonard models are characterized by the emergence of spiraling patterns whose properties are elucidated by a mapping onto a complex

  1. Selenium assimilation and loss by an insect predator and its relationship to Se subcellular partitioning in two prey types

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, Maitee [Institut national de la recherche scientifique - Eau, Terre et Environnement, Universite du Quebec, Quebec City, Quebec, G1K 9A9 (Canada); Hare, Landis [Institut national de la recherche scientifique - Eau, Terre et Environnement, Universite du Quebec, Quebec City, Quebec, G1K 9A9 (Canada)], E-mail: landis@ete.inrs.ca

    2009-03-15

    Subcellular selenium (Se) distributions in the oligochaete Tubifex tubifex and in the insect Chironomus riparius did not vary with Se exposure duration, which was consistent with the observations that the duration of prey Se exposure had little influence on either Se assimilation or loss by a predatory insect (the alderfly Sialis velata). However, these two prey types differed in how Se was distributed in their cells. Overall, the predator assimilated a mean of 66% of the Se present in its prey, which was similar to the mean percentage of Se in prey cells (62%) that was theoretically available for uptake (that is, Se in the protein and organelle fractions). Likewise, data for cadmium, nickel and thallium suggest that predictions of trace element transfer between prey and predator are facilitated by considering the subcellular partitioning of these contaminants in prey cells. - Selenium assimilation by a predatory aquatic insect depends on Se availability in the cells of its prey.

  2. Selenium assimilation and loss by an insect predator and its relationship to Se subcellular partitioning in two prey types

    International Nuclear Information System (INIS)

    Dubois, Maitee; Hare, Landis

    2009-01-01

    Subcellular selenium (Se) distributions in the oligochaete Tubifex tubifex and in the insect Chironomus riparius did not vary with Se exposure duration, which was consistent with the observations that the duration of prey Se exposure had little influence on either Se assimilation or loss by a predatory insect (the alderfly Sialis velata). However, these two prey types differed in how Se was distributed in their cells. Overall, the predator assimilated a mean of 66% of the Se present in its prey, which was similar to the mean percentage of Se in prey cells (62%) that was theoretically available for uptake (that is, Se in the protein and organelle fractions). Likewise, data for cadmium, nickel and thallium suggest that predictions of trace element transfer between prey and predator are facilitated by considering the subcellular partitioning of these contaminants in prey cells. - Selenium assimilation by a predatory aquatic insect depends on Se availability in the cells of its prey

  3. On infrared divergences

    International Nuclear Information System (INIS)

    Parisi, G.

    1979-01-01

    The structure of infrared divergences is studied in superrenormalizable interactions. It is conjectured that there is an extension of the Bogoliubov-Parasiuk-Hepp theorem which copes also with infrared divergences. The consequences of this conjecture on the singularities of the Borel transform in a massless asymptotic free field theory are discussed. The application of these ideas to gauge theories is briefly discussed. (Auth.)

  4. A Sensory-Driven Trade-Off between Coordinated Motion in Social Prey and a Predator's Visual Confusion.

    Directory of Open Access Journals (Sweden)

    Bertrand H Lemasson

    2016-02-01

    Full Text Available Social animals are capable of enhancing their awareness by paying attention to their neighbors, and prey found in groups can also confuse their predators. Both sides of these sensory benefits have long been appreciated, yet less is known of how the perception of events from the perspectives of both prey and predator can interact to influence their encounters. Here we examined how a visual sensory mechanism impacts the collective motion of prey and, subsequently, how their resulting movements influenced predator confusion and capture ability. We presented virtual prey to human players in a targeting game and measured the speed and accuracy with which participants caught designated prey. As prey paid more attention to neighbor movements their collective coordination increased, yet increases in prey coordination were positively associated with increases in the speed and accuracy of attacks. However, while attack speed was unaffected by the initial state of the prey, accuracy dropped significantly if the prey were already organized at the start of the attack, rather than in the process of self-organizing. By repeating attack scenarios and masking the targeted prey's neighbors we were able to visually isolate them and conclusively demonstrate how visual confusion impacted capture ability. Delays in capture caused by decreased coordination amongst the prey depended upon the collection motion of neighboring prey, while it was primarily the motion of the targets themselves that determined capture accuracy. Interestingly, while a complete loss of coordination in the prey (e.g., a flash expansion caused the greatest delay in capture, such behavior had little effect on capture accuracy. Lastly, while increases in collective coordination in prey enhanced personal risk, traveling in coordinated groups was still better than appearing alone. These findings demonstrate a trade-off between the sensory mechanisms that can enhance the collective properties that

  5. Let's go beyond taxonomy in diet description: testing a trait-based approach to prey-predator relationships.

    Science.gov (United States)

    Spitz, Jérôme; Ridoux, Vincent; Brind'Amour, Anik

    2014-09-01

    Understanding 'Why a prey is a prey for a given predator?' can be facilitated through trait-based approaches that identify linkages between prey and predator morphological and ecological characteristics and highlight key functions involved in prey selection. Enhanced understanding of the functional relationships between predators and their prey is now essential to go beyond the traditional taxonomic framework of dietary studies and to improve our knowledge of ecosystem functioning for wildlife conservation and management. We test the relevance of a three-matrix approach in foraging ecology among a marine mammal community in the northeast Atlantic to identify the key functional traits shaping prey selection processes regardless of the taxonomy of both the predators and prey. Our study reveals that prey found in the diet of marine mammals possess functional traits which are directly and significantly linked to predator characteristics, allowing the establishment of a functional typology of marine mammal-prey relationships. We found prey selection of marine mammals was primarily shaped by physiological and morphological traits of both predators and prey, confirming that energetic costs of foraging strategies and muscular performance are major drivers of prey selection in marine mammals. We demonstrate that trait-based approaches can provide a new definition of the resource needs of predators. This framework can be used to anticipate bottom-up effects on marine predator population dynamics and to identify predators which are sensitive to the loss of key prey functional traits when prey availability is reduced. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

  6. Polybrominated diphenyl ethers in birds of prey from Northern China.

    Science.gov (United States)

    Chen, Da; Mai, Bixian; Song, Jie; Sun, Quanhui; Luo, Yong; Luo, Xiaojun; Zeng, Eddy Y; Hale, Robert C

    2007-03-15

    Birds of prey from Northern China (Beijing area) were examined for polybrominated diphenyl ethers (PBDEs). A total of 47 specimens from eight different species were analyzed. Muscle and liver were analyzed separately for each bird. Kidneys were pooled by species. Common kestrels exhibited the highest PBDE levels (mean muscle and liver concentrations of 12300 and 12200 ng/g lipid weight, respectively), with maxima in an individual bird of 31700 in muscle and 40900 ng/g lw in liver. Congener profiles differed between some species, but were generally dominated by the more brominated congeners (e.g., BDE-153, -209, -183, -207). BDE-209 was especially elevated compared to other published reports. Interspecies differences in congener concentrations and profiles may be due to diet, behavior, or biotransformation capacities. BDE-209 was detected in 79.4% of the samples. Common kestrels contained the highest BDE-209 levels (mean/maxima of 2150/6220 in muscle and 2870/12200 ng/g lw in liver). BDE-209 was the dominant congener in tissues from some buzzards, scops owls, and long-eared owls. It was the second most abundant congener in common kestrels. The remarkable levels and dominance of BDE-209 may relate to significant production, usage, or disposal of deca-containing products in China. These observations reinforce the growing view that organisms using terrestrial food chains may have greater exposure to BDE-209.

  7. Falco sparverius (Aves: Falconiformes preying upon Nyctinomops laticaudatus (Chiroptera: Molossidae

    Directory of Open Access Journals (Sweden)

    Ludmilla Moura de Souza Aguiar

    2012-04-01

    Full Text Available In Brazil, there are two published references on the diet of American kestrel falcons, Falco sparverius Linnaeus, 1758, and one is for the Cerrado biome. The only mammal prey so far found in the diet of F. sparverius was the rodent Calomys tener (Winge, 1887. Herein we report on daily hunting activities by American kestrel falcons at a factory in the city of Uberlândia, state of Minas Gerais, southeastern Brazil, during an attempt to remove a bat colony. Two American kestrel falcons were observed on 14 occasions during two consecutive days: in two of these occasions, they were hunting in pairs, from 12:00 p.m. to 3:00 p.m. on 06/X/2003, and from 07:00 a.m. to 11:00 a.m. on 07/X/2003. During this period, American kestrel falcons made 27 hunting attempts and captured four bats of the same species, Nyctinomops laticaudatus (E. Geoffroy St.-Hilaire, 1805 (14.81% success. This report corroborates observations made in the Northern hemisphere, where bats are a dietary item of this falcon. Our findings are noteworthy because they reveal that the known natural predators of bats are few not only in Brazil but also worldwide.

  8. Embedding recurrent neural networks into predator-prey models.

    Science.gov (United States)

    Moreau, Yves; Louiès, Stephane; Vandewalle, Joos; Brenig, Leon

    1999-03-01

    We study changes of coordinates that allow the embedding of ordinary differential equations describing continuous-time recurrent neural networks into differential equations describing predator-prey models-also called Lotka-Volterra systems. We transform the equations for the neural network first into quasi-monomial form (Brenig, L. (1988). Complete factorization and analytic solutions of generalized Lotka-Volterra equations. Physics Letters A, 133(7-8), 378-382), where we express the vector field of the dynamical system as a linear combination of products of powers of the variables. In practice, this transformation is possible only if the activation function is the hyperbolic tangent or the logistic sigmoid. From this quasi-monomial form, we can directly transform the system further into Lotka-Volterra equations. The resulting Lotka-Volterra system is of higher dimension than the original system, but the behavior of its first variables is equivalent to the behavior of the original neural network. We expect that this transformation will permit the application of existing techniques for the analysis of Lotka-Volterra systems to recurrent neural networks. Furthermore, our results show that Lotka-Volterra systems are universal approximators of dynamical systems, just as are continuous-time neural networks.

  9. Recolonizing carnivores and naïve prey: conservation lessons from Pleistocene extinctions.

    Science.gov (United States)

    Berger, J; Swenson, J E; Persson, I L

    2001-02-09

    The current extinction of many of Earth's large terrestrial carnivores has left some extant prey species lacking knowledge about contemporary predators, a situation roughly parallel to that 10,000 to 50,000 years ago, when naive animals first encountered colonizing human hunters. Along present-day carnivore recolonization fronts, brown (also called grizzly) bears killed predator-naive adult moose at disproportionately high rates in Scandinavia, and moose mothers who lost juveniles to recolonizing wolves in North America's Yellowstone region developed hypersensitivity to wolf howls. Although prey that had been unfamiliar with dangerous predators for as few as 50 to 130 years were highly vulnerable to initial encounters, behavioral adjustments to reduce predation transpired within a single generation. The fact that at least one prey species quickly learns to be wary of restored carnivores should negate fears about localized prey extinction.

  10. New scalaranes from the nudibranch Glossodoris atromarginata and its sponge Prey

    Digital Repository Service at National Institute of Oceanography (India)

    Fontana, A.; Cavaliere, P.; Ungur, N.; DeSouza, L.; Parameswaran, P.S.; Cimino, G.

    Two new scalaranes (1 and 2) have been isolated from the dorid nudibranch Glossodoris atromarginata and its prey. The structures were determined by spectral techniques and confirmed by chemical methods. Compounds 1 and 3 showed selective cytotoxic...

  11. Stability analysis of pest-predator interaction model with infectious disease in prey

    Science.gov (United States)

    Suryanto, Agus; Darti, Isnani; Anam, Syaiful

    2018-03-01

    We consider an eco-epidemiological model based on a modified Leslie-Gower predator-prey model. Such eco-epidemiological model is proposed to describe the interaction between pest as the prey and its predator. We assume that the pest can be infected by a disease or pathogen and the predator only eats the susceptible prey. The dynamical properties of the model such as the existence and the stability of biologically feasible equilibria are studied. The model has six type of equilibria, but only three of them are conditionally stable. We find that the predator in this system cannot go extinct. However, the susceptible or the infective prey may disappear in the environment. To support our analytical results, we perform some numerical simulations with different scenario.

  12. Time Delayed Stage-Structured Predator-Prey Model with Birth Pulse and Pest Control Tactics

    Directory of Open Access Journals (Sweden)

    Mei Yan

    2014-01-01

    Full Text Available Normally, chemical pesticides kill not only pests but also their natural enemies. In order to better control the pests, two-time delayed stage-structured predator-prey models with birth pulse and pest control tactics are proposed and analyzed by using impulsive differential equations in present work. The stability threshold conditions for the mature prey-eradication periodic solutions of two models are derived, respectively. The effects of key parameters including killing efficiency rate, pulse period, the maximum birth effort per unit of time of natural enemy, and maturation time of prey on the threshold values are discussed in more detail. By comparing the two threshold values of mature prey-extinction, we provide the fact that the second control tactic is more effective than the first control method.

  13. Natural enemy-mediated indirect interactions among prey species: potential for enhancing biocontrol services in agroecosystems

    NARCIS (Netherlands)

    Chailleux, A.; Mohl, E.K.; Teixeira Alves, M.; Messelink, G.J.; Desneux, N.

    2014-01-01

    Understanding how arthropod pests and their natural enemies interact in complex agroecosystems is essential for pest management programmes. Theory predicts that prey sharing a predator, such as a biological control agent, can indirectly reduce each other's density at equilibrium (apparent

  14. Allee effect in a discrete-time predator-prey system

    International Nuclear Information System (INIS)

    Celik, Canan; Duman, Oktay

    2009-01-01

    In this paper, we study the stability of a discrete-time predator-prey system with and without Allee effect. By analyzing both systems, we first obtain local stability conditions of the equilibrium points without the Allee effect and then exhibit the impact of the Allee effect on stability when it is imposed on prey population. We also show the stabilizing effect of Allee effect by numerical simulations and verify that when the prey population is subject to an Allee effect, the trajectory of the solutions approximates to the corresponding equilibrium point much faster. Furthermore, for some fixed parameter values satisfying necessary conditions, we show that the corresponding equilibrium point moves from instability to stability under the Allee effect on prey population.

  15. Complex dynamics of a stochastic discrete modified Leslie-Gower predator-prey model with Michaelis-Menten type prey harvesting

    Directory of Open Access Journals (Sweden)

    A. Elhassanein

    2014-06-01

    Full Text Available This paper introduced a stochastic discretized version of the modified Leslie-Gower predator-prey model with Michaelis-Menten type prey harvesting. The dynamical behavior of the proposed model was investigated. The existence and stability of the equilibria of the skeleton were studied. Numerical simulations were employed to show the model's complex dynamics by means of the largest Lyapunov exponents, bifurcations, time series diagrams and phase portraits. The effects of noise intensity on its dynamics and the intermittency phenomenon were also discussed via simulation.

  16. Resolution VII International Conference Working Group on Birds of Prey of Northern Eurasia “Birds of Prey of Northern Eurasia: Problems and Adaptation Under Modern Conditions”

    Directory of Open Access Journals (Sweden)

    Igor V. Karyakin

    2017-01-01

    Full Text Available From 19 to 24 September, 2016 VII International Conference of the Working Group on Raptors of Northern Eurasia “Birds of prey of Northern Eurasia: problems and adaptation under modern conditions” was held on the basis of the Sochi National Park. Materials for the conference were presented by 198 ornithologists from Russia, Ukraine, Belarus, Kazakhstan, Moldova, Turkmenistan, Austria, Great Britain, Hungary, Mongolia, Poland, Estonia and the USA, who published 148 articles in two collections “Birds of prey of Northern Eurasia” and “Palearctic Harriers”.

  17. Differential wolf-pack-size persistence and the role of risk when hunting dangerous prey

    Science.gov (United States)

    Barber-Meyer, Shannon M.; Mech, L. David; Newton, Wesley E.; Borg, Bridget

    2016-01-01

    Risk to predators hunting dangerous prey is an emerging area of research and could account for possible persistent differences in gray wolf (Canis lupus) pack sizes. We documented significant differences in long-term wolf-pack-size averages and variation in the Superior National Forest (SNF), Denali National Park and Preserve, Yellowstone National Park, and Yukon, Canada (pwolves’ risk when hunting primary prey, for those packs (N=3) hunting moose (Alces americanus) were significantly larger than those (N=10) hunting white-tailed deer (Odocoileus virginianus) (F1,8=16.50, p=0.004). Our data support the hypothesis that differential pack-size persistence may be perpetuated by differences in primary prey riskiness to wolves, and we highlight two important extensions of this idea: (1) the potential for wolves to provision and defend injured packmates from other wolves and (2) the importance of less-risky, buffer prey to pack-size persistence and year-to-year variation. Risk to predators hunting dangerous prey is an emerging area of research and could account for possible persistent differences in gray wolf (Canis lupus) pack sizes. We documented significant differences in long-term wolf-pack-size averages and variation in the Superior National Forest (SNF), Denali National Park and Preserve, Yellowstone National Park, and Yukon, Canada (pwolves’ risk when hunting primary prey, for those packs (N=3) hunting moose (Alces americanus) were significantly larger than those (N=10) hunting white-tailed deer (Odocoileus virginianus) (F1,8=16.50, p=0.004). Our data support the hypothesis that differential pack-size persistence may be perpetuated by differences in primary prey riskiness to wolves, and we highlight two important extensions of this idea: (1) the potential for wolves to provision and defend injured packmates from other wolves and (2) the importance of less-risky, buffer prey to pack-size persistence and year-to-year variation.

  18. A tiger beetle’s pursuit of prey depends on distance

    Science.gov (United States)

    Noest, R. M.; Wang, Z. Jane

    2017-04-01

    Tiger beetles pursue prey by adjusting their heading according to a time-delayed proportional control law that minimizes the error angle (Haselsteiner et al 2014 J. R. Soc. Interface 11 20140216). This control law can be further interpreted in terms of mechanical actuation: to catch prey, tiger beetles exert a sideways force by biasing their tripod gait in proportion to the error angle measured half a stride earlier. The proportional gain was found to be nearly optimal in the sense that it minimizes the time to point directly toward the prey. For a time-delayed linear proportional controller, the optimal gain, k, is inversely proportional to the time delay, τ, and satisfies kτ =1/e . Here we present evidence that tiger beetles adjust their control gain during their pursuit of prey. Our analysis shows two critical distances: one corresponding to the beetle’s final approach to the prey, and the second, less expected, occurring at a distance around 10 cm for a prey size of 4.5 mm. The beetle initiates its chase using a sub-critical gain and increases the gain to the optimal value once the prey is within this critical distance. Insects use a variety of methods to detect distance, often involving different visual cues. Here we examine two such methods: one based on motion parallax and the other based on the prey’s elevation angle. We show that, in order for the motion parallax method to explain the observed data, the beetle needs to correct for the ratio of the prey’s sideways velocity relative to its own. On the other hand, the simpler method based on the elevation angle can detect both the distance and the prey’s size. Moreover we find that the transition distance corresponds to the accuracy required to distinguish small prey from large predators.

  19. Barred Owl Habitat and Prey: A Review and Synthesis of the Literature

    OpenAIRE

    Livezey, Kent B.

    2007-01-01

    Barred Owls (Strix varia) historically inhabited the forests of eastern North America. During the last century, they expanded their range to include forests throughout the southern provinces of Canada, southeastern Alaska, British Columbia, Washington, Oregon, and northern California. To date, there has been no synthesis of the varied habitats or prey used by Barred Owls in their expanded range. Here I review and synthesize studies concerning habitat (N  =  114) and prey (N  =  43) of Barred ...

  20. Non-pest prey do not disrupt aphid predation by a web-building spider.

    Science.gov (United States)

    Welch, K D; Whitney, T D; Harwood, J D

    2016-02-01

    A generalist predator's ability to contribute to biological control is influenced by the decisions it makes during foraging. Predators often use flexible foraging tactics, which allows them to pursue specific types of prey at the cost of reducing the likelihood of capturing other types of prey. When a pest insect has low nutritional quality or palatability for a predator, the predator is likely to reject that prey in favour of pursuing alternative, non-pest prey. This is often thought to limit the effectiveness of generalist predators in consuming aphids, which are of low nutritional quality for many generalist predators. Here, we report behavioural assays that test the hypothesis that the generalist predator, Grammonota inornata (Araneae: Linyphiidae), preferentially forages for a non-pest prey with high nutritional quality (springtails), and rejects a pest prey with low nutritional quality (aphids). In no-choice assays, molecular gut-content analysis revealed that spiders continued to feed on the low-quality aphids at high rates, even when high-quality springtails were readily available. When provided a choice between aphids and springtails in two-way choice tests, spiders did not show the expected preference for springtails. Decision-making by spiders during foraging therefore appears to be sub-optimal, possibly because of attraction to the less frequently encountered of two preys as part of a dietary diversification strategy. These results indicate that behavioural preferences alone do not necessarily compromise the pest-suppression capacity of natural enemies: even nutritionally sub-optimal pest prey can potentially be subject to predation and suppression by natural enemies.

  1. Hopf bifurcation of a ratio-dependent predator-prey system with time delay

    International Nuclear Information System (INIS)

    Celik, Canan

    2009-01-01

    In this paper, we consider a ratio dependent predator-prey system with time delay where the dynamics is logistic with the carrying capacity proportional to prey population. By considering the time delay as bifurcation parameter, we analyze the stability and the Hopf bifurcation of the system based on the normal form approach and the center manifold theory. Finally, we illustrate our theoretical results by numerical simulations.

  2. Prey selection of lions Panthera leo in a small, enclosed reserve

    Directory of Open Access Journals (Sweden)

    R.J. Power

    2002-12-01

    Full Text Available Annual trends in numbers of ungulate species on a 15 km² reserve from 1993 to 1998, were evaluated in the context of lion Panthera leo reintroduction during 1996, and subsequent predation by them. The ungulate prey base was enumerated annually by aerial counts and a road count that took place during 1998. The lion prey record was obtained from direct observations of a radio-located pride of eight lions and daily reserve management records. All ungulate species that underwent precipituous declines were also the most important prey to lions, comprising over 80 % of their prey, and they were preyed upon according to their availability. Lion predation was causal for the declines in wildebeest Connochaetes taurinus, Blesbok Damaliscus pygargus phillipsi and Warthog Phacochoerus africana, while the decline in Kudu Tragelaphus strepsiceros was only partly ascribed to lions, as other non-lion related mortality sources were identified. The only ungulate species to increase subsequent to lion reintroduction was the Impala Aepyceros melampus, which was furthermore under-selected by lions. The uncontrolled population growth of Impala could have elicited ecological degradation, and it was advised to either not stock Impala, or otherwise control their numbers if lions are unable to do so. Lion hunting success and kill rate, were 21 % (n = 63 and 1 kill/4.4 days, respectively. Three bushpigs Potamochoerus larvatus were killed but not utilised,and this finding is corroborated by an intensive study in Kwazulu-Natal, and this aversion is discussed. Predators can cause unprecedented declines of their prey where the prey are confined to small reserves that have no refuge from predation. On an annual basis, prey may need to be augmented to sustain predators on small reserves

  3. Relationship of Course Woody Debris to Red-Cockaded Woodpecker Prey Diversity and Abundance

    Energy Technology Data Exchange (ETDEWEB)

    Horn, G.S.

    1999-09-03

    The abundance of diversity of prey commonly used by the red-cockaded woodpecker were monitored in experimental plots in which course woody debris was manipulated. In one treatment, all the woody debris over four inches was removed. In the second treatment, the natural amount of mortality remained intact. The overall diversity of prey was unaffected; however, wood roaches were significantly reduced by removal of woody debris. The latter suggests that intensive utilizations or harvesting practices may reduce foraging.

  4. A predator-prey system with stage-structure for predator and nonlocal delay

    DEFF Research Database (Denmark)

    Lin, Z.G.; Pedersen, Michael; Zhang, Lai

    2010-01-01

    This paper deals with the behavior of solutions to the reaction-diffusion system under homogeneous Neumann boundary condition, which describes a prey-predator model with nonlocal delay. Sufficient conditions for the global stability of each equilibrium are derived by the Lyapunov functional...... and the results show that the introduction of stage-structure into predator positively affects the coexistence of prey and predator. Numerical simulations are performed to illustrate the results....

  5. An unprecedented role reversal: ground beetle larvae (Coleoptera: Carabidae lure amphibians and prey upon them.

    Directory of Open Access Journals (Sweden)

    Gil Wizen

    Full Text Available Amphibians often feed on beetle larvae, including those of ground beetles (Carabidae. Preliminary reports have detailed an unusual trophic interaction in which, in contrast, larvae of the ground beetle Epomis prey upon juvenile and adult amphibians. While it is known that these larvae feed exclusively on amphibians, how the predator-prey encounter occurs to the advantage of the beetle larvae had been unknown to date. Using laboratory observations and controlled experiments, we recorded the feeding behavior of Epomis larvae, as well as the behavior of their amphibian prey. Here we reveal that larvae of two species of Epomis (E. circumscriptus and E. dejeani lure their potential predator, taking advantage of the amphibian's predation behavior. The Epomis larva combines a sit-and-wait strategy with unique movements of its antennae and mandibles to draw the attention of the amphibian to the presence of a potential prey. The intensity of this enticement increases with decreasing distance between the larva and the amphibian. When the amphibian attacks, the larva almost always manages to avoid the predator's protracted tongue, exploiting the opportunity to attach itself to the amphibian's body and initiate feeding. Our findings suggest that the trophic interaction between Epomis larvae and amphibians is one of the only natural cases of obligatory predator-prey role reversal. Moreover, this interaction involves a small insect larva that successfully lures and preys on a larger vertebrate. Such role reversal is exceptional in the animal world, extending our perspective of co-evolution in the arms race between predator and prey, and suggesting that counterattack defense behavior has evolved into predator-prey role reversal.

  6. Interactions among Behavioral Responses of Baleen Whales to Acoustic Stimuli, Oceanographic Features, and Prey Availability

    Science.gov (United States)

    2015-09-30

    understand, and effectively mitigate the affects of anthropogenic sound, including military sonar, on these animals . OBJECTIVES The overall...distribution and individual predator behavior has now been measured in portions of five field seasons of SOCAL-BRS. This has included two phases each in in...additional phases of SOCAL-15 with prey mapping are scheduled to occur in October-November 2015. By analyzing prey and predator at fine scales (100s of

  7. Solving Ratio-Dependent Predator-Prey System with Constant Effort Harvesting Using Homotopy Perturbation Method

    Directory of Open Access Journals (Sweden)

    Abdoul R. Ghotbi

    2008-01-01

    Full Text Available Due to wide range of interest in use of bioeconomic models to gain insight into the scientific management of renewable resources like fisheries and forestry, homotopy perturbation method is employed to approximate the solution of the ratio-dependent predator-prey system with constant effort prey harvesting. The results are compared with the results obtained by Adomian decomposition method. The results show that, in new model, there are less computations needed in comparison to Adomian decomposition method.

  8. Functional analysis of a specialized prey processing behavior: winnowing by surfperches (Teleostei: Embiotocidae).

    Science.gov (United States)

    Drucker, E G; Jensen, J S

    1991-12-01

    Several surfperches (Embiotocidae), including the black surfperch, Embiotoca jacksoni, exhibit a specialized prey handling behavior known as winnowing, in which ingested food and non-nutritive debris are separated within the oropharyngeal cavity. Prey items are swallowed, and unpalatable material is ejected from the mouth. Winnowing is believed to play an important role in the partitioning of food resources among sympatric embiotocids. We present a mechanistic model for this separative prey processing based on high-speed video analysis, cineradiography, electromyography, and buccal and opercular cavity pressure transducer recording. Winnowing by embiotocids is characterized by premaxillary protrusions repeated cyclically with reduced oral gape. Protrusion is accompanied by depression of the hyoid apparatus and adduction of the opercula. Alternating expansion and contraction of the buccal and opercular cavities generate regular pressure waveforms that indicate bidirectional water flow during processing. Separation of food from debris by Embiotoca jacksoni occurs in three phases. The prey-debris bolus is transported anteriorly and posteriorly within the oropharyngeal cavity and is then sheared by the pharyngeal jaws. Mechanical processing is complemented by the rinsing action of water currents during hydraulic prey transport. The feeding apparatus of Embiotoca jacksoni is functionally versatile, although not obviously specialized relative to that of nonwinnowing surfperches. Protrusion of the premaxillae and depression of the hyoid apparatus are critical to both prey capture and subsequent prey processing. The pharyngeal jaws exhibit kinematic patterns during separation of food from debris distinct from those observed during mastication of uncontaminated prey. This behavioral flexibility facilitates resource partitioning and the coexistence of E. jacksoni in sympatric embiotocid assemblages.

  9. Using process algebra to develop predator-prey models of within-host parasite dynamics.

    Science.gov (United States)

    McCaig, Chris; Fenton, Andy; Graham, Andrea; Shankland, Carron; Norman, Rachel

    2013-07-21

    As a first approximation of immune-mediated within-host parasite dynamics we can consider the immune response as a predator, with the parasite as its prey. In the ecological literature of predator-prey interactions there are a number of different functional responses used to describe how a predator reproduces in response to consuming prey. Until recently most of the models of the immune system that have taken a predator-prey approach have used simple mass action dynamics to capture the interaction between the immune response and the parasite. More recently Fenton and Perkins (2010) employed three of the most commonly used prey-dependent functional response terms from the ecological literature. In this paper we make use of a technique from computing science, process algebra, to develop mathematical models. The novelty of the process algebra approach is to allow stochastic models of the population (parasite and immune cells) to be developed from rules of individual cell behaviour. By using this approach in which individual cellular behaviour is captured we have derived a ratio-dependent response similar to that seen in the previous models of immune-mediated parasite dynamics, confirming that, whilst this type of term is controversial in ecological predator-prey models, it is appropriate for models of the immune system. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Predator-induced flow disturbances alert prey, from the onset of an attack

    Science.gov (United States)

    Casas, Jérôme; Steinmann, Thomas

    2014-01-01

    Many prey species, from soil arthropods to fish, perceive the approach of predators, allowing them to escape just in time. Thus, prey capture is as important to predators as prey finding. We extend an existing framework for understanding the conjoint trajectories of predator and prey after encounters, by estimating the ratio of predator attack and prey danger perception distances, and apply it to wolf spiders attacking wood crickets. Disturbances to air flow upstream from running spiders, which are sensed by crickets, were assessed by computational fluid dynamics with the finite-elements method for a much simplified spider model: body size, speed and ground effect were all required to obtain a faithful representation of the aerodynamic signature of the spider, with the legs making only a minor contribution. The relationship between attack speed and the maximal distance at which the cricket can perceive the danger is parabolic; it splits the space defined by these two variables into regions differing in their values for this ratio. For this biological interaction, the ratio is no greater than one, implying immediate perception of the danger, from the onset of attack. Particular attention should be paid to the ecomechanical aspects of interactions with such small ratio, because of the high degree of bidirectional coupling of the behaviour of the two protagonists. This conclusion applies to several other predator–prey systems with sensory ecologies based on flow sensing, in air and water. PMID:25030986

  11. Age-related decline in lateralised prey capture success in Garnett's bushbaby (Otolemur garnettii).

    Science.gov (United States)

    Hanbury, David B; Edens, Kyle D; Legg, Claire E; Harrell, Shane P; Greer, Tammy F; Watson, Sheree L

    2012-01-01

    We examined differences in prey capture success when reaching for moving prey with the preferred and non-preferred hand (as determined previously using stationary food items) in 12 Garnett's bushbabies (Otolemur garnettii). Hand preference was determined by a test of simple reaching for stationary food items. We assessed both the frequency of hand use and success rates for each hand in capturing live mealworms. We also examined the effect of age on overall prey capture success. Subjects were individually presented with live mealworms in a cup partially filled with a cornmeal medium. The preferred hand was used significantly more often than the non-preferred hand to obtain the moving prey; however, no differences were found in the frequency of usage of the left vs the right hand. Furthermore, there were no differences in the success rates of the left vs the right hand, nor the preferred vs the non-preferred hand. There was a significant negative correlation between age and prey capture success. These data suggest that age, rather than preferred hand, may be the most relevant factor in the bushbabies' prey capture success.

  12. Disturbed flow in an aquatic environment may create a sensory refuge for aggregated prey

    Directory of Open Access Journals (Sweden)

    Asa Johannesen

    2017-03-01

    Full Text Available Predators use olfactory cues moved within water and air to locate prey. Because prey aggregations may produce more cue and be easier to detect, predation could limit aggregation size. However, disturbance in the flow may diminish the reliability of odour as a prey cue, impeding predator foraging success and efficiency. We explore how different cue concentrations (as a proxy for prey group size affect risk to prey by fish predators in disturbed (more turbulent or mixed and non-disturbed (less mixed flowing water. We find that increasing odour cue concentration increases predation risk and disturbing the flow reduces predation risk. At high cue concentration fish were able to locate the cue source in both disturbed and non-disturbed flow, but at medium concentrations, predators only located the cue source more often than expected by chance in non-disturbed flow. This suggests that objects disturbing flow provide a sensory refuge allowing prey to form larger groups, but that group sizes may be limited by level of disturbance to the flow.

  13. On the Gause predator-prey model with a refuge: a fresh look at the history.

    Science.gov (United States)

    Křivan, Vlastimil

    2011-04-07

    This article re-analyses a prey-predator model with a refuge introduced by one of the founders of population ecology Gause and his co-workers to explain discrepancies between their observations and predictions of the Lotka-Volterra prey-predator model. They replaced the linear functional response used by Lotka and Volterra by a saturating functional response with a discontinuity at a critical prey density. At concentrations below this critical density prey were effectively in a refuge while at a higher densities they were available to predators. Thus, their functional response was of the Holling type III. They analyzed this model and predicted existence of a limit cycle in predator-prey dynamics. In this article I show that their model is ill posed, because trajectories are not well defined. Using the Filippov method, I define and analyze solutions of the Gause model. I show that depending on parameter values, there are three possibilities: (1) trajectories converge to a limit cycle, as predicted by Gause, (2) trajectories converge to an equilibrium, or (3) the prey population escapes predator control and grows to infinity. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Prey and Non-prey Arthropods Sharing a Host Plant: Effects on Induced Volatile Emission and Predator Attraction

    Science.gov (United States)

    Hordijk, Cornelis A.; Posthumus, Maarten A.; Dicke, Marcel

    2008-01-01

    It is well established that plants infested with a single herbivore species can attract specific natural enemies through the emission of herbivore-induced volatiles. However, it is less clear what happens when plants are simultaneously attacked by more than one species. We analyzed volatile emissions of lima bean and cucumber plants upon multi-species herbivory by spider mites (Tetranychus urticae) and caterpillars (Spodoptera exigua) in comparison to single-species herbivory. Upon herbivory by single or multiple species, lima bean and cucumber plants emitted volatile blends that comprised mostly the same compounds. To detect additive, synergistic, or antagonistic effects, we compared the multi-species herbivory volatile blend with the sum of the volatile blends induced by each of the herbivore species feeding alone. In lima bean, the majority of compounds were more strongly induced by multi-species herbivory than expected based on the sum of volatile emissions by each of the herbivores separately, potentially caused by synergistic effects. In contrast, in cucumber, two compounds were suppressed by multi-species herbivory, suggesting the potential for antagonistic effects. We also studied the behavioral responses of the predatory mite Phytoseiulus persimilis, a specialized natural enemy of spider mites. Olfactometer experiments showed that P. persimilis preferred volatiles induced by multi-species herbivory to volatiles induced by S. exigua alone or by prey mites alone. We conclude that both lima bean and cucumber plants effectively attract predatory mites upon multi-species herbivory, but the underlying mechanisms appear different between these species. PMID:18185960

  15. Alien Mink Predation and Colonisation Processes of Rodent Prey on Small Islands of the Baltic Sea: Does Prey Naivete Matter?

    International Nuclear Information System (INIS)

    Fey, K.; Korpimaki, E.; Banks, P.B.

    2010-01-01

    Colonisation, an important part of meta-population dynamics of fragmented populations, depends on both the dispersal ability and the ability to establish in the new habitat. Predation can hinder successful establishment of prey, and where the predation pressure comes from an alien predator, the effects on colonisation might be devastating. We studied the establishment of field voles (Microtus agrestis) inhabiting small islands of the archipelago of the Baltic Sea, SW Finland, under presence and absence of the alien American mink (Mustela vison). We translocated experienced voles from islands with mink, and inexperienced voles from islands from which mink had been removed, to other islands where mink was present or absent. By radio-tracking we studied survival, space and micro habitat use of voles within four weeks after translocation. Survival of voles on mink islands was significantly lower than on mink-free islands, but experienced voles did not survive better than inexperienced voles. Experienced voles were more often located in juniper habitats than inexperienced voles, but they appeared not to gain any survival benefit from altered micro habitat use. This study provides novel evidence, that alien mink predation inhibits establishment of colonising field voles and may thus ultimately induce extinction of voles from the outer archipelago.

  16. Luminescence from potassium feldspars stimulated by infrared and green light

    DEFF Research Database (Denmark)

    Duller, G.A.T.; Bøtter-Jensen, L.

    1993-01-01

    A series of experiments are reported which investigate stimulated luminescence from potassium feldspar. The aim is to provide a basic phenomenological description of the response of the material to stimulation by heat, infrared radiation (875 DELTA 80 nm) and a green light wavelength band from 5 15...... to 560 nm. Two conclusions are drawn: firstly it is suggested that the majority of the trapped charge responsible for the infrared stimulated luminescence signal does not give rise to a thermoluminescence signal, and secondly that a large traction of the two optically stimulated luminescence signals...

  17. A Generalist Protist Predator Enables Coexistence in Multitrophic Predator-Prey Systems Containing a Phage and the Bacterial Predator Bdellovibrio

    Directory of Open Access Journals (Sweden)

    Julia Johnke

    2017-10-01

    Full Text Available Complex ecosystems harbor multiple predators and prey species whose direct and indirect interactions are under study. In particular, the combined effects of predator diversity and resource preference on prey removal are not known. To understand the effect of interspecies interactions, combinations of micro-predators—i.e., protists (generalists, predatory bacteria (semi-specialists, and phages (specialists—and bacterial prey were tracked over a 72-h period in miniature membrane bioreactors. While specialist predators alone drove their preferred prey to extinction, the inclusion of a generalist resulted in uniform losses among prey species. Most importantly, presence of a generalist predator enabled coexistence of all predators and prey. As the generalist predator also negatively affected the other predators, we suggest that resource partitioning between predators and the constant availability of resources for bacterial growth due to protist predation stabilizes the system and keeps its diversity high. The appearance of resistant prey strains and subsequent evolution of specialist predators unable to infect the ancestral prey implies that multitrophic communities are able to persist and stabilize themselves. Interestingly, the appearance of BALOs and phages unable to infect their prey was only observed for the BALO or phage in the absence of additional predators or prey species indicating that competition between predators might influence coevolutionary dynamics.

  18. Sea urchins, their predators and prey in SW Portugal

    Directory of Open Access Journals (Sweden)

    Nuno Mamede

    2014-06-01

    Full Text Available Sea urchins play a key role structuring benthic communities of rocky shores through an intense herbivory. The most abundant sea urchin species on shallow rocky subtidal habitats of the SW coast of Portugal is Paracentrotus lividus (Echinodermata: Echinoidea. It is considered a key species in various locations throughout its geographical distribution by affecting the structure of macroalgae communities and may cause the abrupt transformation of habitats dominated by foliose algae to habitats dominated by encrusting algae - the urchin barrens. The removal of P. lividus predators by recreational and commercial fishing is considered a major cause of this phenomenon by affecting the trophic relationships between predators, sea urchins and algae communities. Marine protected areas (MPAs usually lead to the recovery of important predator species that control sea urchin populations and restore habitats dominated by foliose macroalgae. Therefore, MPAs provide a good opportunity to test cascading effects and indirect impacts of fishing at the ecosystem level. The ecological role of P. lividus was studied on rocky subtidal habitats of the SW coast of Portugal (Alentejo considering three trophic levels: population of P. lividus, their predators (fish and shellfish and their prey (macroalgae communities. Several studies were conducted: (1 a non-destructive observational study on the abundance and distribution patterns of P. lividus, their predators and preys, comparing areas with different protection; (2 a manipulative in situ study with cages to assess the role of P. lividus as an herbivore and the influence of predation; (3 a descriptive study of P. lividus predators based on underwater filming; (4 and a study of human perception on these trophic relationships and other issues on sea urchin ecology and fishery, based on surveys made to fishermen and divers. Subtidal studies were performed with SCUBA diving at 3-12 m deep. Results indicate that in the

  19. Effectiveness of community forestry in Prey Long forest, Cambodia.

    Science.gov (United States)

    Lambrick, Frances H; Brown, Nick D; Lawrence, Anna; Bebber, Daniel P

    2014-04-01

    Cambodia has 57% forest cover, the second highest in the Greater Mekong region, and a high deforestation rate (1.2%/year, 2005-2010). Community forestry (CF) has been proposed as a way to reduce deforestation and support livelihoods through local management of forests. CF is expanding rapidly in Cambodia. The National Forests Program aims to designate one million hectares of forest to CF by 2030. However, the effectiveness of CF in conservation is not clear due to a global lack of controlled comparisons, multiple meanings of CF, and the context-specific nature of CF implementation. We assessed the effectiveness of CF by comparing 9 CF sites with paired controls in state production forest in the area of Prey Long forest, Cambodia. We assessed forest condition in 18-20 randomly placed variable-radius plots and fixed-area regeneration plots. We surveyed 10% of households in each of the 9 CF villages to determine the proportion that used forest products, as a measure of household dependence on the forest. CF sites had fewer signs of anthropogenic damage (cut stems, stumps, and burned trees), higher aboveground biomass, more regenerating stems, and reduced canopy openness than control areas. Abundance of economically valuable species, however, was higher in control sites. We used survey results and geographic parameters to model factors affecting CF outcomes. Interaction between management type, CF or control, and forest dependence indicated that CF was more effective in cases where the community relied on forest products for subsistence use and income. © 2014 Society for Conservation Biology.

  20. Are owl pellets good estimators of prey abundance?

    Directory of Open Access Journals (Sweden)

    Analia Andrade

    2016-07-01

    Full Text Available Some ecologists have been skeptics about the use of owl pellets to estimate small mammal’s fauna. This is due to the assumptions required by this method: (a that owls hunt at random, and (b that pellets represent a random sample from the environment. We performed statistical analysis to test these assumptions and to assess the effectiveness of Barn owl pellets as a useful estimator of field abundances of its preys. We used samples collected in the arid Extra-Andean Patagonia along an altitudinal environmental gradient from lower Monte ecoregion to upper Patagonian steppe ecoregion, with a mid-elevation ecotone. To test if owls hunt at random, we estimated expected pellet frequency by creating a distribution of random pellets, which we compared with data using a simulated chi-square. To test if pellets represent a random sample from the environment, differences between ecoregions were evaluated by PERMANOVAs with Bray–Curtis dissimilarities. We did not find evidence that owls foraged non-randomly. Therefore, we can assume that the proportions of the small mammal’s species in the diet are representative of the proportions of the species in their communities. Only Monte is different from other ecoregions. The ecotone samples are grouped with those of Patagonian steppes. There are no real differences between localities in the small mammal’s abundances in each of these ecoregions and/or Barn owl pellets cannot detect patterns at a smaller spatial scale. Therefore, we have no evidence to invalidate the use of owl pellets at an ecoregional scale.

  1. Signal Words

    Science.gov (United States)

    SIGNAL WORDS TOPIC FACT SHEET NPIC fact sheets are designed to answer questions that are commonly asked by the ... making decisions about pesticide use. What are Signal Words? Signal words are found on pesticide product labels, ...

  2. Effects of prey abundance, distribution, visual contrast and morphology on selection by a pelagic piscivore

    Science.gov (United States)

    Hansen, Adam G.; Beauchamp, David A.

    2014-01-01

    Most predators eat only a subset of possible prey. However, studies evaluating diet selection rarely measure prey availability in a manner that accounts for temporal–spatial overlap with predators, the sensory mechanisms employed to detect prey, and constraints on prey capture.We evaluated the diet selection of cutthroat trout (Oncorhynchus clarkii) feeding on a diverse planktivore assemblage in Lake Washington to test the hypothesis that the diet selection of piscivores would reflect random (opportunistic) as opposed to non-random (targeted) feeding, after accounting for predator–prey overlap, visual detection and capture constraints.Diets of cutthroat trout were sampled in autumn 2005, when the abundance of transparent, age-0 longfin smelt (Spirinchus thaleichthys) was low, and 2006, when the abundance of smelt was nearly seven times higher. Diet selection was evaluated separately using depth-integrated and depth-specific (accounted for predator–prey overlap) prey abundance. The abundance of different prey was then adjusted for differences in detectability and vulnerability to predation to see whether these factors could explain diet selection.In 2005, cutthroat trout fed non-randomly by selecting against the smaller, transparent age-0 longfin smelt, but for the larger age-1 longfin smelt. After adjusting prey abundance for visual detection and capture, cutthroat trout fed randomly. In 2006, depth-integrated and depth-specific abundance explained the diets of cutthroat trout well, indicating random feeding. Feeding became non-random after adjusting for visual detection and capture. Cutthroat trout selected strongly for age-0 longfin smelt, but against similar sized threespine stickleback (Gasterosteus aculeatus) and larger age-1 longfin smelt in 2006. Overlap with juvenile sockeye salmon (O. nerka) was minimal in both years, and sockeye salmon were rare in the diets of cutthroat trout.The direction of the shift between random and non-random selection

  3. Infrared laser diagnostics for ITER

    International Nuclear Information System (INIS)

    Hutchinson, D.P.; Richards, R.K.; Ma, C.H.

    1995-01-01

    Two infrared laser-based diagnostics are under development at ORNL for measurements on burning plasmas such as ITER. The primary effort is the development of a CO 2 laser Thomson scattering diagnostic for the measurement of the velocity distribution of confined fusion-product alpha particles. Key components of the system include a high-power, single-mode CO 2 pulsed laser, an efficient optics system for beam transport and a multichannel low-noise infrared heterodyne receiver. A successful proof-of-principle experiment has been performed on the Advanced Toroidal Facility (ATF) stellerator at ORNL utilizing scattering from electron plasma frequency satellites. The diagnostic system is currently being installed on Alcator C-Mod at MIT for measurements of the fast ion tail produced by ICRH heating. A second diagnostic under development at ORNL is an infrared polarimeter for Faraday rotation measurements in future fusion experiments. A preliminary feasibility study of a CO 2 laser tangential viewing polarimeter for measuring electron density profiles in ITER has been completed. For ITER plasma parameters and a polarimeter wavelength of 10.6 microm, a Faraday rotation of up to 26 degree is predicted. An electro-optic polarization modulation technique has been developed at ORNL. Laboratory tests of this polarimeter demonstrated a sensitivity of ≤ 0.01 degree. Because of the similarity in the expected Faraday rotation in ITER and Alcator C-Mod, a collaboration between ORNL and the MIT Plasma Fusion Center has been undertaken to test this polarimeter system on Alcator C-Mod. A 10.6 microm polarimeter for this measurement has been constructed and integrated into the existing C-Mod multichannel two-color interferometer. With present experimental parameters for C-Mod, the predicted Faraday rotation was on the order of 0.1 degree. Significant output signals were observed during preliminary tests. Further experiment and detailed analyses are under way

  4. Barrier Infrared Detector (BIRD)

    Data.gov (United States)

    National Aeronautics and Space Administration — A recent breakthrough in MWIR detector design, has resulted in a high operating temperature (HOT) barrier infrared detector (BIRD) that is capable of spectral...

  5. Infrared Sky Surveys

    Science.gov (United States)

    Price, Stephan D.

    2009-02-01

    A retrospective is given on infrared sky surveys from Thomas Edison’s proposal in the late 1870s to IRAS, the first sensitive mid- to far-infrared all-sky survey, and the mid-1990s experiments that filled in the IRAS deficiencies. The emerging technology for space-based surveys is highlighted, as is the prominent role the US Defense Department, particularly the Air Force, played in developing and applying detector and cryogenic sensor advances to early mid-infrared probe-rocket and satellite-based surveys. This technology was transitioned to the infrared astronomical community in relatively short order and was essential to the success of IRAS, COBE and ISO. Mention is made of several of the little known early observational programs that were superseded by more successful efforts.

  6. Infrared emission from protostars

    International Nuclear Information System (INIS)

    Adams, F.C.; Shu, F.H.

    1985-01-01

    The emergent spectral energy distribution at infrared to radio wavelengths is calculated for the simplest theoretical construct of a low-mass protostar. It is shown that the emergent spectrum in the infrared is insensitive to the details assumed for the temperature profile as long as allowance is made for a transition from optically thick to optically thin conditions and luminosity conservation isenforced at the inner and outer shells. The radiation in the far infrared and submillimeter wavelengths depends on the exact assumptions made for grain opacities at low frequencies. An atlas of emergent spectral energy distributions is presented for a grid of values of the instantaneous mass of the protostar and the mass infall rate. The attenuated contribution of the accretion shock to the near-infrared radiation is considered. 50 references

  7. History of infrared detectors

    Science.gov (United States)

    Rogalski, A.

    2012-09-01

    This paper overviews the history of infrared detector materials starting with Herschel's experiment with thermometer on February 11th, 1800. Infrared detectors are in general used to detect, image, and measure patterns of the thermal heat radiation which all objects emit. At the beginning, their development was connected with thermal detectors, such as thermocouples and bolometers, which are still used today and which are generally sensitive to all infrared wavelengths and operate at room temperature. The second kind of detectors, called the photon detectors, was mainly developed during the 20th Century to improve sensitivity and response time. These detectors have been extensively developed since the 1940's. Lead sulphide (PbS) was the first practical IR detector with sensitivity to infrared wavelengths up to ˜3 μm. After World War II infrared detector technology development was and continues to be primarily driven by military applications. Discovery of variable band gap HgCdTe ternary alloy by Lawson and co-workers in 1959 opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design. Many of these advances were transferred to IR astronomy from Departments of Defence research. Later on civilian applications of infrared technology are frequently called "dual-use technology applications." One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies, as well as the noticeable price decrease in these high cost technologies. In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays (FPAs). Development in FPA technology has revolutionized infrared imaging. Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.

  8. Additive Manufacturing Infrared Inspection

    Science.gov (United States)

    Gaddy, Darrell; Nettles, Mindy

    2015-01-01

    The Additive Manufacturing Infrared Inspection Task started the development of a real-time dimensional inspection technique and digital quality record for the additive manufacturing process using infrared camera imaging and processing techniques. This project will benefit additive manufacturing by providing real-time inspection of internal geometry that is not currently possible and reduce the time and cost of additive manufactured parts with automated real-time dimensional inspections which deletes post-production inspections.

  9. Transcriptomic response of the mycoparasitic fungus Trichoderma atroviride to the presence of a fungal prey.

    Science.gov (United States)

    Seidl, Verena; Song, Lifu; Lindquist, Erika; Gruber, Sabine; Koptchinskiy, Alexeji; Zeilinger, Susanne; Schmoll, Monika; Martínez, Pedro; Sun, Jibin; Grigoriev, Igor; Herrera-Estrella, Alfredo; Baker, Scott E; Kubicek, Christian P

    2009-11-30

    Combating the action of plant pathogenic microorganisms by mycoparasitic fungi has been announced as an attractive biological alternative to the use of chemical fungicides since two decades. The fungal genus Trichoderma includes a high number of taxa which are able to recognize, combat and finally besiege and kill their prey. Only fragments of the biochemical processes related to this ability have been uncovered so far, however. We analyzed genome-wide gene expression changes during the begin of physical contact between Trichoderma atroviride and two plant pathogens Botrytis cinerea and Rhizoctonia solani, and compared with gene expression patterns of mycelial and conidiating cultures, respectively. About 3000 ESTs, representing about 900 genes, were obtained from each of these three growth conditions. 66 genes, represented by 442 ESTs, were specifically and significantly overexpressed during onset of mycoparasitism, and the expression of a subset thereof was verified by expression analysis. The upregulated genes comprised 18 KOG groups, but were most abundant from the groups representing posttranslational processing, and amino acid metabolism, and included components of the stress response, reaction to nitrogen shortage, signal transduction and lipid catabolism. Metabolic network analysis confirmed the upregulation of the genes for amino acid biosynthesis and of those involved in the catabolism of lipids and aminosugars. The analysis of the genes overexpressed during the onset of mycoparasitism in T. atroviride has revealed that the fungus reacts to this condition with several previously undetected physiological reactions. These data enable a new and more comprehensive interpretation of the physiology of mycoparasitism, and will aid in the selection of traits for improvement of biocontrol strains by recombinant techniques.

  10. Transcriptomic response of the mycoparasitic fungus Trichoderma atroviride to the presence of a fungal prey

    Energy Technology Data Exchange (ETDEWEB)

    Seidl, Verena; Song, Lifu; Lindquist, Erika; Gruber, Sabine; Koptchinskiy, Alexeji; Zeilinger, Susanne; Schmoll, Monika; Martinez, Pedro; Sun, Jibin; Grigoriev, Igor; Herrera-Estrella, Alfredo; Baker, Scott E; Kubicek, Christian P.

    2010-07-23

    BACKGROUND: Combating the action of plant pathogenic microorganisms by mycoparasitic fungi has been announced as an attractive biological alternative to the use of chemical fungicides since two decades. The fungal genus Trichoderma includes a high number of taxa which are able to recognize, combat and finally besiege and kill their prey. Only fragments of the biochemical processes related to this ability have been uncovered so far, however. RESULTS: We analyzed genome-wide gene expression changes during the begin of physical contact between Trichoderma atroviride and two plant pathogens Botrytis cinerea and Rhizoctonia solani, and compared with gene expression patterns of mycelial and conidiating cultures, respectively. About 3000 ESTs, representing about 900 genes, were obtained from each of these three growth conditions. 66 genes, represented by 442 ESTs, were specifically and significantly overexpressed during onset of mycoparasitism, and the expression of a subset thereof was verified by expression analysis. The upregulated genes comprised 18 KOG groups, but were most abundant from the groups representing posttranslational processing, and amino acid metabolism, and included components of the stress response, reaction to nitrogen shortage, signal transduction and lipid catabolism. Metabolic network analysis confirmed the upregulation of the genes for amino acid biosynthesis and of those involved in the catabolism of lipids and aminosugars. CONCLUSION: The analysis of the genes overexpressed during the onset of mycoparasitism in T. atroviride has revealed that the fungus reacts to this condition with several previously undetected physiological reactions. These data enable a new and more comprehensive interpretation of the physiology of mycoparasitism, and will aid in the selection of traits for improvement of biocontrol strains by recombinant techniques.

  11. Dual-guild herbivory disrupts predator-prey interactions in the field.

    Science.gov (United States)

    Blubaugh, Carmen K; Asplund, Jacob S; Eigenbrode, Sanford D; Morra, Matthew J; Philips, Christopher R; Popova, Inna E; Reganold, John P; Snyder, William E

    2018-05-01

    Plant defenses often mediate whether competing chewing and sucking herbivores indirectly benefit or harm one another. Dual-guild herbivory also can muddle plant signals used by specialist natural enemies to locate prey, further complicating the net impact of herbivore-herbivore interactions in naturally diverse settings. While dual-guild herbivore communities are common in nature, consequences for top-down processes are unclear, as chemically mediated tri-trophic interactions are rarely evaluated in field environments. Combining observational and experimental approaches in the open field, we test a prediction that chewing herbivores interfere with top-down suppression of phloem feeders on Brassica oleracea across broad landscapes. In a two-year survey of 52 working farm sites, we found that parasitoid and aphid densities on broccoli plants positively correlated at farms where aphids and caterpillars rarely co-occurred, but this relationship disappeared at farms where caterpillars commonly co-occurred. In a follow-up experiment, we compared single and dual-guild herbivore communities at four local farm sites and found that caterpillars (P. rapae) caused a 30% reduction in aphid parasitism (primarily by Diaeretiella rapae), and increased aphid colony (Brevicoryne brassicae) growth at some sites. Notably, in the absence of predators, caterpillars indirectly suppressed, rather than enhanced, aphid growth. Amid considerable ecological noise, our study reveals a pattern of apparent commensalism: herbivore-herbivore facilitation via relaxed top-down suppression. This work suggests that enemy-mediated apparent commensalism may override constraints to growth induced by competing herbivores in field environments, and emphasizes the value of placing chemically mediated interactions within their broader environmental and community contexts. © 2018 by the Ecological Society of America.

  12. Transcriptomic response of the mycoparasitic fungus Trichoderma atroviride to the presence of a fungal prey

    Directory of Open Access Journals (Sweden)

    Herrera-Estrella Alfredo

    2009-11-01

    Full Text Available Abstract Background Combating the action of plant pathogenic microorganisms by mycoparasitic fungi has been announced as an attractive biological alternative to the use of chemical fungicides since two decades. The fungal genus Trichoderma includes a high number of taxa which are able to recognize, combat and finally besiege and kill their prey. Only fragments of the biochemical processes related to this ability have been uncovered so far, however. Results We analyzed genome-wide gene expression changes during the begin of physical contact between Trichoderma atroviride and two plant pathogens Botrytis cinerea and Rhizoctonia solani, and compared with gene expression patterns of mycelial and conidiating cultures, respectively. About 3000 ESTs, representing about 900 genes, were obtained from each of these three growth conditions. 66 genes, represented by 442 ESTs, were specifically and significantly overexpressed during onset of mycoparasitism, and the expression of a subset thereof was verified by expression analysis. The upregulated genes comprised 18 KOG groups, but were most abundant from the groups representing posttranslational processing, and amino acid metabolism, and included components of the stress response, reaction to nitrogen shortage, signal transduction and lipid catabolism. Metabolic network analysis confirmed the upregulation of the genes for amino acid biosynthesis and of those involved in the catabolism of lipids and aminosugars. Conclusion The analysis of the genes overexpressed during the onset of mycoparasitism in T. atroviride has revealed that the fungus reacts to this condition with several previously undetected physiological reactions. These data enable a new and more comprehensive interpretation of the physiology of mycoparasitism, and will aid in the selection of traits for improvement of biocontrol strains by recombinant techniques.

  13. Analysis of the SIAM Infrared Acquisition System

    Energy Technology Data Exchange (ETDEWEB)

    Varnado, S.G.

    1974-02-01

    This report describes and presents the results of an analysis of the performance of the infrared acquisition system for a Self-Initiated Antiaircraft Missile (SIAM). A description of the optical system is included, and models of target radiant intensity, atmospheric transmission, and background radiance are given. Acquisition probabilities are expressed in terms of the system signal-to-noise ratio. System performance against aircraft and helicopter targets is analyzed, and background discrimination techniques are discussed. 17 refs., 22 figs., 6 tabs.

  14. Models for infrared atmospheric radiation

    Science.gov (United States)

    Tiwari, S. N.

    1976-01-01

    Line and band models for infrared spectral absorption are discussed. Radiative transmittance and integrated absorptance of Lorentz, Doppler, and voigt line profiles were compared for a range of parameters. It was found that, for the intermediate path lengths, the combined Lorentz-Doppler (Voigt) profile is essential in calculating the atmospheric transmittance. Narrow band model relations for absorptance were used to develop exact formulations for total absorption by four wide band models. Several continuous correlations for the absorption of a wide band model were compared with the numerical solutions of the wide band models. By employing the line-by-line and quasi-random band model formulations, computational procedures were developed for evaluating transmittance and upwelling atmospheric radiance. Homogeneous path transmittances were calculated for selected bands of CO, CO2, and N2O and compared with experimental measurements. The upwelling radiance and signal change in the wave number interval of the CO fundamental band were also calculated.

  15. Foraging mechanisms of siscowet lake trout (Salvelinus namaycush siscowet) on pelagic prey

    Science.gov (United States)

    Keyler, Trevor D.; Hrabik, Thomas R.; Austin, C. Lee; Gorman, Owen T.; Mensinger, Allen F.

    2015-01-01

    The reaction distance, angle of attack, and foraging success were determined for siscowet lake trout (Salvelinus namaycush siscowet) during laboratory trials under lighting conditions that approximated downwelling spectral irradiance and intensity (9.00 × 108–1.06 × 1014 photons m− 2 s− 1) at daytime depths. Siscowet reaction distance in response to golden shiners (Notemigonus crysoleucas) was directly correlated with increasing light intensity until saturation at 1.86 × 1011 photons m− 2 s− 1, above which reaction distance was constant within the range of tested light intensities. At the lowest tested light intensity, sensory detection was sufficient to locate prey at 25 ± 2 cm, while increasing light intensities increased reaction distance up to 59 ± 2 cm at 1.06 × 1014 photons m− 2 s− 1. Larger prey elicited higher reaction distances than smaller prey at all light intensities while moving prey elicited higher reaction distances than stationary prey at the higher light intensities (6.00 × 109 to 1.06 × 1014 photons m− 2 s− 1). The capture and consumption of prey similarly increased with increasing light intensity while time to capture decreased with increasing light intensity. The majority of orientations toward prey occurred within 120° of the longitudinal axis of the siscowet's eyes, although reaction distances among 30° increments along the entire axis were not significantly different. The developed predictive model will help determine reaction distances for siscowet in various photic environments and will help identify the mechanisms and behavior that allow for low light intensity foraging within freshwater systems.

  16. Responses to river inundation pressures control prey selection of riparian beetles.

    Directory of Open Access Journals (Sweden)

    Matt J O'Callaghan

    Full Text Available Riparian habitats are subjected to frequent inundation (flooding and are characterised by food webs that exhibit variability in aquatic/terrestrial subsidies across the ecotone. The strength of this subsidy in active riparian floodplains is thought to underpin local biodiversity. Terrestrial invertebrates dominate the fauna, exhibiting traits that allow exploitation of variable aquatic subsidies while reducing inundation pressures, leading to inter-species micro-spatial positioning. The effect these strategies have on prey selection is not known. This study hypothesised that plasticity in prey choice from either aquatic or terrestrial sources is an important trait linked to inundation tolerance and avoidance.We used hydrological, isotopic and habitat analyses to investigate the diet of riparian Coleoptera in relation to inundation risk and relative spatial positioning in the floodplain. The study examined patch scale and longitudinal changes in utilisation of the aquatic subsidy according to species traits. Prey sourced from terrestrial or emerging/stranded aquatic invertebrates varied in relation to traits for inundation avoidance or tolerance strategies. Traits that favoured rapid dispersal corresponded with highest proportions of aquatic prey, with behavioural traits further predicting uptake. Less able dispersers showed minimal use of aquatic subsidy and switched to a terrestrial diet under moderate inundation pressures. All trait groups showed a seasonal shift in diet towards terrestrial prey in the early spring. Prey selection became exaggerated towards aquatic prey in downstream samples.Our results suggest that partitioning of resources and habitat creates overlapping niches that increase the processing of external subsidies in riparian habitats. By demonstrating functional complexity, this work advances understanding of floodplain ecosystem processes and highlights the importance of hydrological variability. With an increasing interest

  17. Prey capture kinematics and four-bar linkages in the bay pipefish, Syngnathus leptorhynchus.

    Science.gov (United States)

    Flammang, Brooke E; Ferry-Graham, Lara A; Rinewalt, Christopher; Ardizzone, Daniele; Davis, Chante; Trejo, Tonatiuh

    2009-01-01

    Because of their modified cranial morphology, syngnathid pipefishes have been described as extreme suction feeders. The presumption is that these fishes use their elongate snout much like a pipette in capturing planktonic prey. In this study, we quantify the contribution of suction to the feeding strike and quantitatively describe the prey capture mechanics of the bay pipefish Syngnathus leptorhynchus, focusing specifically on the role of both cranial elevation and snout movement. We used high-speed video to capture feeding sequences from nine individuals feeding on live brine shrimp. Sequences were digitized in order to calculate kinematic variables that could be used to describe prey capture. Prey capture was very rapid, from 2 to 6 ms from the onset of cranial rotation. We found that suction contributed at most about one-eighth as much as ram to the reduction of the distance between predator and prey. This movement of the predator was due almost exclusively to movement of the snout and neurocranium rather than movement of the whole body. The body was positioned ventral and posterior to the prey and the snout was rotated dorsally by as much as 21 degrees, thereby placing the mouth immediately behind the prey for capture. The snout did not follow the identical trajectory as the neurocranium, however, and reached a maximum angle of only about 10 degrees. The snout consists, in part, of elongate suspensorial elements and the linkages among these elements are retained despite changes in shape. Thus, when the neurocranium is rotated, the four-bar linkage that connects this action with hyoid depression simultaneously acts to expand and straighten the snout relative to the neurocranium. We confirm the presence of a four-bar linkage that facilitates these kinematics by couplings between the pectoral girdle, urohyal, hyoid complex, and the neurocranium-suspensorium complex.

  18. Assessing breeding potential of peregrine falcons based on chlorinated hydrocarbon concentrations in prey

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, J.E. [Canadian Wildlife Service, Pacific Wildlife Research Centre, 5421 Robertson Rd., RR no. 1, Delta, British Columbia, V4K 3N2 (Canada)]. E-mail: john.elliott@ec.gc.ca; Miller, M.J. [Iolaire Ecological Consulting, 7899 Thrasher St., Mission, British Columbia, V2V 5H3 (Canada); Wilson, L.K. [Canadian Wildlife Service, Pacific Wildlife Research Centre, 5421 Robertson Rd., RR no. 1, Delta, British Columbia, V4K 3N2 (Canada)

    2005-03-01

    Peregrine falcons (Falco peregrinus) now breed successfully in most areas of North America from which they were previously extirpated. The loss during the mid-part of the last century of many of the world's peregrine populations was largely a consequence of impaired reproduction caused by the effects of DDE on eggshell quality and embryo hatchability. Population recovery has been attributed to re-introduction efforts, coupled with regulatory restrictions on the use of organochlorine pesticides. Peregrines have not returned to breed in some areas, such as the Okanagan Valley of British Columbia. That region has been extensively planted in fruit orchards which were treated annually with DDT during the early 1950s to the 1970s. Ongoing contamination of avian species, including potential peregrine prey, inhabiting orchards has been documented. In response to an initiative to release peregrines around the city of Kelowna in the Okanagan Valley, we collected potential peregrine prey species and analyzed whole bodies for chlorinated hydrocarbon residues. We used a simple bioaccumulation model to predict concentrations of DDE in peregrine eggs using concentrations in prey and estimates of dietary makeup as input. Peregrines would be expected to breed successfully only if they fed on a diet primarily of doves. Feeding on as little as 10% of other species such as starlings, robins, gulls and magpies would produce DDE concentrations in peregrine eggs greater than the threshold of 15 mg/kg. We also estimated the critical concentration of DDE in total prey to be about 0.5 mg/kg, one half of the previous most conservative criterion for peregrine prey. Concentrations of dieldrin and PCBs in peregrine prey are less than suggested critical levels. - Based on the level of DDE contamination of prey items, it seems unlikely that peregrine falcons could breed successfully throughout most of the Okanagan Valley of British Columbia.

  19. Modelling landscape-level numerical responses of predators to prey: the case of cats and rabbits.

    Directory of Open Access Journals (Sweden)

    Jennyffer Cruz

    Full Text Available Predator-prey systems can extend over large geographical areas but empirical modelling of predator-prey dynamics has been largely limited to localised scales. This is due partly to difficulties in estimating predator and prey abundances over large areas. Collection of data at suitably large scales has been a major problem in previous studies of European rabbits (Oryctolagus cuniculus and their predators. This applies in Western Europe, where conserving rabbits and predators such as Iberian lynx (Lynx pardinus is important, and in other parts of the world where rabbits are an invasive species supporting populations of introduced, and sometimes native, predators. In pastoral regions of New Zealand, rabbits are the primary prey of feral cats (Felis catus that threaten native fauna. We estimate the seasonal numerical response of cats to fluctuations in rabbit numbers in grassland-shrubland habitat across the Otago and Mackenzie regions of the South Island of New Zealand. We use spotlight counts over 1645 km of transects to estimate rabbit and cat abundances with a novel modelling approach that accounts simultaneously for environmental stochasticity, density dependence and varying detection probability. Our model suggests that cat abundance is related consistently to rabbit abundance in spring and summer, possibly through increased rabbit numbers improving the fecundity and juvenile survival of cats. Maintaining rabbits at low abundance should therefore suppress cat numbers, relieving predation pressure on native prey. Our approach provided estimates of the abundance of cats and rabbits over a large geographical area. This was made possible by repeated sampling within each season, which allows estimation of detection probabilities. A similar approach could be applied to predator-prey systems elsewhere, and could be adapted to any method of direct observation in which there is no double-counting of individuals. Reliable estimates of numerical

  20. Changes in Alaskan soft-bottom prey communities along a gradient in sea otter predation

    Science.gov (United States)

    Kvitek, R.G.; Oliver, J.S.; DeGange, A.R.; Anderson, B.S.

    1992-01-01

    Sea Otter (Enhydra lutris), well documented as "keystone" predators in rocky marine communities, were found to exert a strong influence on infaunal prey communities in soft-sediment habitats. Direct and indirect effects of sea otter predation on subtidal soft-bottom prey communities were evaluated along a temporal gradient of sea otter occupancy around the Kodiak Archipelago. The results indicate that Kodiak otters forage primarily on bivalve prey and dramatically reduce infaunal bivalve and green sea urchin (Strongylocentrotus droebachiensis) prey populations. Bivalve prey abundance, biomass, and size were inversely related to duration of sea otter occupancy. The relative conditions of shells discarded by otters in shallow ( 20 m) water at the same sites indicate that otters first exploited Saxidomus in shallow-water feeding areas, and later switched to Macoma spp. in deeper water. Otter-cracked shells of the deep-burrowing clam Tresus capax were rarely found, even at otter foraging sites where the clam accounted for the majority of available prey biomass, suggesting that it has a partial depth refuge from otter predation. The indirect effects of otter predation included substratum disturbance and the facilitation of sea star predation on infaunal prey. Sea stars, Pycnopodia helianthoides, were attracted to experimentally dug excavations as well as natural sea otter foraging pits, where the sea stars foraged on smaller size classes of infaunal bivalves than those eaten by otters. Otters also discard clam shells on the sediment surface and expose old, buried shells during excavation. Surface shells were found to provide attachment sites for large anemones and kelp. Our study shows that sea otters can affect soft-sediment communities, not only through predation, as in rocky habitats, but also through disturbance, and thus retain a high degree of influence in two very different habitat types.

  1. Predation on exotic zebra mussels by native fishes: Effects on predator and prey

    Science.gov (United States)

    Magoulick, D.D.; Lewis, L.C.

    2002-01-01

    1. Exotic zebra mussels, Dreissena polymorpha, occur in southern U.S. waterways in high densities, but little is known about the interaction between native fish predators and zebra mussels. Previous studies have suggested that exotic zebra mussels are low profitability prey items and native vertebrate predators are unlikely to reduce zebra mussel densities. We tested these hypotheses by observing prey use of fishes, determining energy content of primary prey species of fishes, and conducting predator exclusion experiments in Lake Dardanelle, Arkansas. 2. Zebra mussels were the primary prey eaten by 52.9% of blue catfish, Ictalurus furcatus; 48.2% of freshwater drum, Aplodinotus grunniens; and 100% of adult redear sunfish, Lepomis microlophus. Blue catfish showed distinct seasonal prey shifts, feeding on zebra mussels in summer and shad, Dorosoma spp., during winter. Energy content (joules g-1) of blue catfish prey (threadfin shad, Dorosoma petenense; gizzard shad, D. cepedianum; zebra mussels; and asiatic clams, Corbicula fluminea) showed a significant species by season interaction, but shad were always significantly greater in energy content than bivalves examined as either ash-free dry mass or whole organism dry mass. Fish predators significantly reduced densities of large zebra mussels (>5 mm length) colonising clay tiles in the summers of 1997 and 1998, but predation effects on small zebra mussels (???5 mm length) were less clear. 3. Freshwater drum and redear sunfish process bivalve prey by crushing shells and obtain low amounts of higher-energy food (only the flesh), whereas blue catfish lack a shell-crushing apparatus and ingest large amounts of low-energy food per unit time (bivalves with their shells). Blue catfish appeared to select the abundant zebra mussel over the more energetically rich shad during summer, then shifted to shad during winter when shad experienced temperature-dependent stress and mortality. Native fish predators can suppress adult zebra

  2. Management intensity and vegetation complexity affect web-building spiders and their prey.

    Science.gov (United States)

    Diehl, Eva; Mader, Viktoria L; Wolters, Volkmar; Birkhofer, Klaus

    2013-10-01

    Agricultural management and vegetation complexity affect arthropod diversity and may alter trophic interactions between predators and their prey. Web-building spiders are abundant generalist predators and important natural enemies of pests. We analyzed how management intensity (tillage, cutting of the vegetation, grazing by cattle, and synthetic and organic inputs) and vegetation complexity (plant species richness, vegetation height, coverage, and density) affect rarefied richness and composition of web-building spiders and their prey with respect to prey availability and aphid predation in 12 habitats, ranging from an uncut fallow to a conventionally managed maize field. Spiders and prey from webs were collected manually and the potential prey were quantified using sticky traps. The species richness of web-building spiders and the order richness of prey increased with plant diversity and vegetation coverage. Prey order richness was lower at tilled compared to no-till sites. Hemipterans (primarily aphids) were overrepresented, while dipterans, hymenopterans, and thysanopterans were underrepresented in webs compared to sticky traps. The per spider capture efficiency for aphids was higher at tilled than at no-till sites and decreased with vegetation complexity. After accounting for local densities, 1.8 times more aphids were captured at uncut compared to cut sites. Our results emphasize the functional role of web-building spiders in aphid predation, but suggest negative effects of cutting or harvesting. We conclude that reduced management intensity and increased vegetation complexity help to conserve local invertebrate diversity, and that web-building spiders at sites under low management intensity (e.g., semi-natural habitats) contribute to aphid suppression at the landscape scale.

  3. Ocean Acidification Disrupts Prey Responses to Predator Cues but Not Net Prey Shell Growth in Concholepas concholepas (loco)

    Science.gov (United States)

    Manríquez, Patricio H.; Jara, María Elisa; Mardones, María Loreto; Navarro, Jorge M.; Torres, Rodrigo; Lardies, Marcos A.; Vargas, Cristian A.; Duarte, Cristian; Widdicombe, Stephen; Salisbury, Joseph; Lagos, Nelson A.

    2013-01-01

    Background Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. Methodology/Principal Findings The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716±12 and 1036±14 µatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 µatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. Conclusions and Significance These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature. PMID:23844231

  4. Ocean acidification disrupts prey responses to predator cues but not net prey shell growth in Concholepas concholepas (loco.

    Directory of Open Access Journals (Sweden)

    Patricio H Manríquez

    Full Text Available BACKGROUND: Most research on Ocean Acidification (OA has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. METHODOLOGY/PRINCIPAL FINDINGS: The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE (716 ± 12 and 1036 ± 14 µatm CO2 compared to those reared at concentrations equivalent to those presently found in the surface ocean (388 ± 8 µatm CO2. When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. CONCLUSIONS AND SIGNIFICANCE: These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.

  5. Ocean acidification disrupts prey responses to predator cues but not net prey shell growth in Concholepas concholepas (loco).

    Science.gov (United States)

    Manríquez, Patricio H; Jara, María Elisa; Mardones, María Loreto; Navarro, Jorge M; Torres, Rodrigo; Lardies, Marcos A; Vargas, Cristian A; Duarte, Cristian; Widdicombe, Stephen; Salisbury, Joseph; Lagos, Nelson A

    2013-01-01

    Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716 ± 12 and 1036 ± 14 µatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388 ± 8 µatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.

  6. Kelp Forests versus Urchin Barrens: Alternate Stable States and Their Effect on Sea Otter Prey Quality in the Aleutian Islands

    Directory of Open Access Journals (Sweden)

    Nathan L. Stewart

    2012-01-01

    Full Text Available Macroalgal and urchin barren communities are alternately stable and persist in the Aleutians due to sea otter presence and absence. In the early 1990s a rapid otter population decline released urchins from predation and caused a shift to the urchin-dominated state. Despite increases in urchin abundance, otter numbers continued to decline. Although debated, prey quality changes have been implicated in current otter population status. This study examined otter prey abundance, size, biomass, and potential energy density in remnant kelp forest and urchin-dominated communities to determine if alternate stable states affect prey quality. Findings suggest that although urchin barrens provide more abundant urchin prey, individual urchins are smaller and provide lower biomass and potential energy density compared to kelp forests. Shifts to urchin barrens do affect prey quality but changes are likely compensated by increased prey densities and are insufficient in explaining current otter population status in the Aleutians.

  7. The diets of Hispaniolan colubrid snakes : I. Introduction and prey genera.

    Science.gov (United States)

    Henderson, Robert W

    1984-05-01

    Approximately 1590 Hispaniolan colubrid snakes representing six genera and eight species were examined for prey remains (Alsophis cantherigerus, Antillophis parvifrons, Darlingtonia haetiana, Hypsirhynchus ferox, Ialtris dorsalis, Uromacer catesbyi, U. frenatus, and U. oxyrhynchus). The snakes were collected at many localities over a span of 80 years.Of 426 prey items, 77.9% were lizards (of which 69.6% were anoles), 19% frogs, 2.6% birds and mammals, and 0.5% other snakes. Darlingtonia was the only snake that did not exploit lizards; it fed exclusively on Eleutherodactylus frogs, including egg clutches. Disregarding Darlingtonia, there is no size class of Hispaniolan colubrids between 20-90 cm SVL that does not prey primarily on Anolis. Certain prey genera are added to, or deleted from, diets depending on snake size, but the data suggest that snake SVL alone does little to dictate what prey genera (or groups) are eaten. Shannon-Wiener values (H') indicate that Darlingtonia has the narrowest trophic niche, while Alsophis and Ialtris have the widest. Values of H' are not correlated with snake SVL, but highly significant (Peats diurnally active (anoles) and diurnally quiescent (hylid frogs) prey with almost equal frequency.Within Maglio's cantherigerus species assemblage, in which an Alsophis cantherigerus-like snake was ancestral to the other species, and in which longsnouted Uromacer are the most morphologically derived, there is an obvious trend toward trophic specialization on Hispaniola. The West Indies have provided an ideal natural laboratory for the investigation of many aspects of vertebrate ecology, and an arena in which to test theories of island biogeography. The most extensively studied West Indian vertebrates have been the lizards of the iguanid genus Anolis. Conversely, the ecology of West Indian snakes has been largely ignored. This is surprising in light of the fact that much has been written about Anolis predation, but little has been written about

  8. Toward a community ecology of landscapes: predicting multiple predator-prey interactions across geographic space.

    Science.gov (United States)

    Schmitz, Oswald J; Miller, Jennifer R B; Trainor, Anne M; Abrahms, Briana

    2017-09-01

    Community ecology was traditionally an integrative science devoted to studying interactions between species and their abiotic environments in order to predict species' geographic distributions and abundances. Yet for philosophical and methodological reasons, it has become divided into two enterprises: one devoted to local experimentation on species interactions to predict community dynamics; the other devoted to statistical analyses of abiotic and biotic information to describe geographic distribution. Our goal here is to instigate thinking about ways to reconnect the two enterprises and thereby return to a tradition to do integrative science. We focus specifically on the community ecology of predators and prey, which is ripe for integration. This is because there is active, simultaneous interest in experimentally resolving the nature and strength of predator-prey interactions as well as explaining patterns across landscapes and seascapes. We begin by describing a conceptual theory rooted in classical analyses of non-spatial food web modules used to predict species interactions. We show how such modules can be extended to consideration of spatial context using the concept of habitat domain. Habitat domain describes the spatial extent of habitat space that predators and prey use while foraging, which differs from home range, the spatial extent used by an animal to meet all of its daily needs. This conceptual theory can be used to predict how different spatial relations of predators and prey could lead to different emergent multiple predator-prey interactions such as whether predator consumptive or non-consumptive effects should dominate, and whether intraguild predation, predator interference or predator complementarity are expected. We then review the literature on studies of large predator-prey interactions that make conclusions about the nature of multiple predator-prey interactions. This analysis reveals that while many studies provide sufficient information

  9. Why plankton modellers should reconsider using rectangular hyperbolic (Michaelis-Menten, Monod descriptions of predator-prey interactions

    Directory of Open Access Journals (Sweden)

    Kevin John Flynn

    2016-09-01

    Full Text Available Rectangular hyperbolic type 2 (RHt2; Michaelis-Menten or Monod -like functions are commonly used to describe predation kinetics in plankton models, either alone or together with a prey selectivity algorithm deploying the same half-saturation constant for all prey types referenced to external prey biomass abundance. We present an analysis that indicates that such descriptions are liable to give outputs that are not plausible according to encounter theory. This is especially so for multi-prey type applications or where changes are made to the maximum feeding rate during a simulation. The RHt2 approach also gives no or limited potential for descriptions of events such as true de-selection of prey, effects of turbulence on encounters, or changes in grazer motility with satiation. We present an alternative, which carries minimal parameterisation effort and computational cost, linking allometric algorithms relating prey abundance and encounter rates to a prey-selection function controlled by satiation. The resultant Satiation-Controlled-Encounter-Based (SCEB function provides a flexible construct describing numeric predator-prey interactions with biomass-feedback control of grazing. The SCEB function includes an attack component similar to that in the Holling disk equation but SCEB differs in having only a single (satiation-based handling constant and an explicit maximum grazing rate. We argue that there is no justification for continuing to deploy RHt2 functions to describe plankton predator-prey interactions.

  10. Presence of Native Prey Does Not Divert Predation on Exotic Pests by Harmonia axyridis in Its Indigenous Range

    Science.gov (United States)

    Zhang, Gui Fen; Lövei, Gábor L; Wu, Xia; Wan, Fang Hao

    2016-01-01

    In China, two invasive pests, Bemisia tabaci MEAM1 (Gennadius) and Frankliniella occidentalis (Pergande), often co-occur with the native pest, Aphis gossypii (Glover), on plants of Malvaceae and Cucurbitaceae. All three are preyed on by the native ladybird, Harmonia axyridis (Pallas); however, the native predator might be expected to prefer native prey to the exotic ones due to a shared evolutionary past. In order to clarify whether the presence of native prey affected the consumption of these two invasive species by the native predator, field-cage experiments were conducted. A duplex qPCR was used to simultaneously detect both non-native pests within the gut of the predator. H. axyridis readily accepted both invasive prey species, but preferred B. tabaci. With all three prey species available, H. axyridis consumption of B. tabaci was 39.3±2.2% greater than consumption of F. occidentalis. The presence of A. gossypii reduced (by 59.9% on B. tabaci, and by 60.6% on F. occidentalis), but did not stop predation on the two exotic prey when all three were present. The consumption of B. tabaci was similar whether it was alone or together with A. gossypii. However, the presence of aphids reduced predation on the invasive thrips. Thus, some invasive prey may be incorporated into the prey range of a native generalist predator even in the presence of preferred native prey. PMID:27391468

  11. The effect of turbidity and prey fish density on consumption rates of piscivorous Eurasian perch Perca fluviatilis

    DEFF Research Database (Denmark)

    Jacobsen, Lene; Berg, Søren; Baktoft, Henrik

    2014-01-01

    piscivorous Eurasian perch Perca fluviatilis L. This was done in outdoor mesocosm (16 m2) experiments with clear water and two levels of turbidity (25 and 105 NTU) and two prey fish densities [3.1 and 12.5 roach Rutilus rutilus (L.) individuals m–2]. Perch consumption rates were affected by visibility less...... than expected, while they were highly affected by increased prey fish density. Perch responded to high prey density in all visibility conditions, indicating that prey density is more crucial for consumption than visibility in turbid lakes...

  12. An objective approach to determining the weight ranges of prey preferred by and accessible to the five large African carnivores.

    Directory of Open Access Journals (Sweden)

    Hayley S Clements

    Full Text Available Broad-scale models describing predator prey preferences serve as useful departure points for understanding predator-prey interactions at finer scales. Previous analyses used a subjective approach to identify prey weight preferences of the five large African carnivores, hence their accuracy is questionable. This study uses a segmented model of prey weight versus prey preference to objectively quantify the prey weight preferences of the five large African carnivores. Based on simulations of known predator prey preference, for prey species sample sizes above 32 the segmented model approach detects up to four known changes in prey weight preference (represented by model break-points with high rates of detection (75% to 100% of simulations, depending on number of break-points and accuracy (within 1.3±4.0 to 2.7±4.4 of known break-point. When applied to the five large African carnivores, using carnivore diet information from across Africa, the model detected weight ranges of prey that are preferred, killed relative to their abundance, and avoided by each carnivore. Prey in the weight ranges preferred and killed relative to their abundance are together termed "accessible prey". Accessible prey weight ranges were found to be 14-135 kg for cheetah Acinonyx jubatus, 1-45 kg for leopard Panthera pardus, 32-632 kg for lion Panthera leo, 15-1600 kg for spotted hyaena Crocuta crocuta and 10-289 kg for wild dog Lycaon pictus. An assessment of carnivore diets throughout Africa found these accessible prey weight ranges include 88±2% (cheetah, 82±3% (leopard, 81±2% (lion, 97±2% (spotted hyaena and 96±2% (wild dog of kills. These descriptions of prey weight preferences therefore contribute to our understanding of the diet spectrum of the five large African carnivores. Where datasets meet the minimum sample size requirements, the segmented model approach provides a means of determining, and comparing, the prey weight range preferences of any carnivore

  13. An objective approach to determining the weight ranges of prey preferred by and accessible to the five large African carnivores.

    Science.gov (United States)

    Clements, Hayley S; Tambling, Craig J; Hayward, Matt W; Kerley, Graham I H

    2014-01-01

    Broad-scale models describing predator prey preferences serve as useful departure points for understanding predator-prey interactions at finer scales. Previous analyses used a subjective approach to identify prey weight preferences of the five large African carnivores, hence their accuracy is questionable. This study uses a segmented model of prey weight versus prey preference to objectively quantify the prey weight preferences of the five large African carnivores. Based on simulations of known predator prey preference, for prey species sample sizes above 32 the segmented model approach detects up to four known changes in prey weight preference (represented by model break-points) with high rates of detection (75% to 100% of simulations, depending on number of break-points) and accuracy (within 1.3±4.0 to 2.7±4.4 of known break-point). When applied to the five large African carnivores, using carnivore diet information from across Africa, the model detected weight ranges of prey that are preferred, killed relative to their abundance, and avoided by each carnivore. Prey in the weight ranges preferred and killed relative to their abundance are together termed "accessible prey". Accessible prey weight ranges were found to be 14-135 kg for cheetah Acinonyx jubatus, 1-45 kg for leopard Panthera pardus, 32-632 kg for lion Panthera leo, 15-1600 kg for spotted hyaena Crocuta crocuta and 10-289 kg for wild dog Lycaon pictus. An assessment of carnivore diets throughout Africa found these accessible prey weight ranges include 88±2% (cheetah), 82±3% (leopard), 81±2% (lion), 97±2% (spotted hyaena) and 96±2% (wild dog) of kills. These descriptions of prey weight preferences therefore contribute to our understanding of the diet spectrum of the five large African carnivores. Where datasets meet the minimum sample size requirements, the segmented model approach provides a means of determining, and comparing, the prey weight range preferences of any carnivore species.

  14. Prey should hide more randomly when a predator attacks more persistently.

    Science.gov (United States)

    Gal, Shmuel; Alpern, Steve; Casas, Jérôme

    2015-12-06

    When being searched for and then (if found) pursued by a predator, a prey animal has a choice between choosing very randomly among hiding locations so as to be hard to find or alternatively choosing a location from which it is more likely to successfully flee if found. That is, the prey can choose to be hard to find or hard to catch, if found. In our model, capture of prey requires both finding it and successfully pursuing it. We model this dilemma as a zero-sum repeated game between predator and prey, with the eventual capture probability as the pay-off to the predator. We find that the more random hiding strategy is better when the chances of repeated pursuit, which are known to be related to area topography, are high. Our results extend earlier results of Gal and Casas, where there was at most only a single pursuit. In that model, hiding randomly was preferred by the prey when the predator has only a few looks. Thus, our new multistage model shows that the effect of more potential looks is opposite. Our results can be viewed as a generalization of search games to the repeated game context and are in accordance with observed escape behaviour of different animals. © 2015 The Author(s).

  15. Fatal attraction: adaptations to prey on native frogs imperil snakes after invasion of toxic toads.

    Science.gov (United States)

    Hagman, Mattias; Phillips, Benjamin L; Shine, Richard

    2009-08-07

    Adaptations that enhance fitness in one situation can become liabilities if circumstances change. In tropical Australia, native snake species are vulnerable to the invasion of toxic cane toads. Death adders (Acanthophis praelongus) are ambush foragers that (i) attract vertebrate prey by caudal luring and (ii) handle anuran prey by killing the frog then waiting until the frog's chemical defences degrade before ingesting it. These tactics render death adders vulnerable to toxic cane toads (Bufo marinus), because toads elicit caudal luring more effectively than do native frogs, and are more readily attracted to the lure. Moreover, the strategy of delaying ingestion of a toad after the strike does not prevent fatal poisoning, because toad toxins (unlike those of native frogs) do not degrade shortly after the prey dies. In our laboratory and field trials, half of the death adders died after ingesting a toad, showing that the specialized predatory behaviours death adders use to capture and process prey render them vulnerable to this novel prey type. The toads' strong response to caudal luring also renders them less fit than native anurans (which largely ignored the lure): all toads bitten by adders died. Together, these results illustrate the dissonance in behavioural adaptations that can arise following the arrival of invasive species, and reveal the strong selection that occurs when mutually naive species first interact.

  16. Artificial night light alters nocturnal prey interception outcomes for morphologically variable spiders

    Directory of Open Access Journals (Sweden)

    Suet Wai Yuen

    2017-12-01

    Full Text Available Artificial night light has the potential to significantly alter visually-dependent species interactions. However, examples of disruptions of species interactions through changes in light remain rare and how artificial night light may alter predator–prey relationships are particularly understudied. In this study, we examined whether artificial night light could impact prey attraction and interception in Nephila pilipes orb weaver spiders, conspicuous predators who make use of yellow color patterns to mimic floral resources and attract prey to their webs. We measured moth prey attraction and interception responses to treatments where we experimentally manipulated the color/contrast of spider individuals in the field (removed yellow markings and also set up light manipulations. We found that lit webs had lower rates of moth interception than unlit webs. Spider color, however, had no clear impact on moth interception or attraction rates in lit nor unlit webs. The results show that night light can reduce prey interception for spiders. Additionally, this study highlights how environmental and morphological variation can complicate simple predictions of ecological light pollution’s disruption of species interactions.

  17. Extinction and Permanence of a General Predator-Prey System with Impulsive Perturbations

    Directory of Open Access Journals (Sweden)

    Xianning Liu

    2012-01-01

    Full Text Available A general predator-prey system is studied in a scheme where there is periodic impulsive perturbations. This scheme has the potential to protect the predator from extinction but under some conditions may also serve to lead to extinction of the prey. Conditions for extinction and permanence are obtained via the comparison methods involving monotone theory of impulsive systems and multiple Liapunov functions, which establish explicit bounds on solutions. The existence of a positive periodic solution is also studied by the bifurcation theory. Application is given to a Lotka-Volterra predator-prey system with periodic impulsive immigration of the predator. It is shown that the results are quite different from the corresponding system without impulsive immigration, where extinction of the prey can never be achieved. The prey will be extinct or permanent independent of whether the system without impulsive effect immigration is permanent or not. The model and its results suggest an approach of pest control which proves more effective than the classical one.

  18. Falcons pursue prey using visual motion cues: new perspectives from animal-borne cameras.

    Science.gov (United States)

    Kane, Suzanne Amador; Zamani, Marjon

    2014-01-15

    This study reports on experiments on falcons wearing miniature videocameras mounted on their backs or heads while pursuing flying prey. Videos of hunts by a gyrfalcon (Falco rusticolus), gyrfalcon (F. rusticolus)/Saker falcon (F. cherrug) hybrids and peregrine falcons (F. peregrinus) were analyzed to determine apparent prey positions on their visual fields during pursuits. These video data were then interpreted using computer simulations of pursuit steering laws observed in insects and mammals. A comparison of the empirical and modeling data indicates that falcons use cues due to the apparent motion of prey on the falcon's visual field to track and capture flying prey via a form of motion camouflage. The falcons also were found to maintain their prey's image at visual angles consistent with using their shallow fovea. These results should prove relevant for understanding the co-evolution of pursuit and evasion, as well as the development of computer models of predation and the integration of sensory and locomotion systems in biomimetic robots.

  19. Adaptive behaviour and multiple equilibrium states in a predator-prey model.

    Science.gov (United States)

    Pimenov, Alexander; Kelly, Thomas C; Korobeinikov, Andrei; O'Callaghan, Michael J A; Rachinskii, Dmitrii

    2015-05-01

    There is evidence that multiple stable equilibrium states are possible in real-life ecological systems. Phenomenological mathematical models which exhibit such properties can be constructed rather straightforwardly. For instance, for a predator-prey system this result can be achieved through the use of non-monotonic functional response for the predator. However, while formal formulation of such a model is not a problem, the biological justification for such functional responses and models is usually inconclusive. In this note, we explore a conjecture that a multitude of equilibrium states can be caused by an adaptation of animal behaviour to changes of environmental conditions. In order to verify this hypothesis, we consider a simple predator-prey model, which is a straightforward extension of the classic Lotka-Volterra predator-prey model. In this model, we made an intuitively transparent assumption that the prey can change a mode of behaviour in response to the pressure of predation, choosing either "safe" of "risky" (or "business as usual") behaviour. In order to avoid a situation where one of the modes gives an absolute advantage, we introduce the concept of the "cost of a policy" into the model. A simple conceptual two-dimensional predator-prey model, which is minimal with this property, and is not relying on odd functional responses, higher dimensionality or behaviour change for the predator, exhibits two stable co-existing equilibrium states with basins of attraction separated by a separatrix of a saddle point. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Prey-predator dynamics driven by the solar radiation - Part 1

    International Nuclear Information System (INIS)

    Sertorio, L.

    2000-01-01

    In this paper is studied a model ecosystem represented by two components: prey and predator. The predator feeds only on the prey, the prey, in turn, feeds on the solar radiation. In this scheme the two-species dynamics is no longer independent of the external physical conditions. Such independence was instead postulated in the Lotka-Volterra scheme. In this paper is considered the growth of the prey not unbounded (exponential), but logistic, where the saturation factor is governed by the available solar flux, more precisely by the percent of the solar flux that contains the photon frequencies which can drive the photosynthesis. In this way the solar flux represents the driving term of the dynamics, as it is expected in general for a realistic ecosystem. The system is asymptotically stable. The equilibrium values of the prey and predator numbers depend on several parameters. The system contains two nonlinear coupling terms and two coupling parameters. The dependence of the equilibrium point on the coupling parameters is studied in detail. According to this model, it can be defined a predator efficiency and a global solar efficiency. It is discussed the relationship between these two functions of the coupling parameters and the maximum value that the predator population can reach

  1. Assessing arsenic intake from groundwater and rice by residents in Prey Veng province, Cambodia

    International Nuclear Information System (INIS)

    Phan, Kongkea; Phan, Samrach; Heng, Savoeun; Huoy, Laingshun; Kim, Kyoung-Woong

    2014-01-01

    We investigated total daily intake of As by residents in Prey Veng province in the Mekong River basin of Cambodia. Groundwater (n = 11), rice (n = 11) and fingernail (n = 23) samples were randomly collected from the households and analyzed for total As by inductively coupled plasma mass spectrometry. Calculation indicated that daily dose of inorganic As was greater than the lower limits on the benchmark dose for a 0.5% increased incidence of lung cancer (BMDL 0.5 equals to 3.0 μg d −1 kg −1 body wt. ). Moreover, positive correlation between As in fingernail and daily dose of As from groundwater and rice and total daily dose of As were found. These results suggest that the Prey Veng residents are exposed to As in groundwater. As in rice is an additional source which is attributable to high As accumulation in human bodies in the Mekong River basin of Cambodia. -- Highlights: • We investigated total daily intake of As in Prey Veng province of Cambodia. • Residents in Prey Veng study area are at risk of As in groundwater. • As in rice is an additional source for high As accumulation in human bodies. -- Calculation of total daily intake indicated that Prey Veng residents are at risk of As in groundwater while As in rice is an additional source for high As accumulation in human bodies

  2. Ultimate predators: lionfish have evolved to circumvent prey risk assessment abilities.

    Science.gov (United States)

    Lönnstedt, Oona M; McCormick, Mark I

    2013-01-01

    Invasive species cause catastrophic alterations to communities worldwide by changing the trophic balance within ecosystems. Ever since their introduction in the mid 1980's common red lionfish, Pterois volitans, are having dramatic impacts on the Caribbean ecosystem by displacing native species and disrupting food webs. Introduced lionfish capture prey at extraordinary rates, altering the composition of benthic communities. Here we demonstrate that the extraordinary success of the introduced lionfish lies in its capacity to circumvent prey risk assessment abilities as it is virtually undetectable by prey species in its native range. While experienced prey damselfish, Chromis viridis, respond with typical antipredator behaviours when exposed to a common predatory rock cod (Cephalopholis microprion) they fail to visibly react to either the scent or visual presentation of the red lionfish, and responded only to the scent (not the visual cue) of a lionfish of a different genus, Dendrochirus zebra. Experienced prey also had much higher survival when exposed to the two non-invasive predators compared to P. volitans. The cryptic nature of the red lionfish has enabled it to be destructive as a predator and a highly successful invasive species.

  3. Ultimate predators: lionfish have evolved to circumvent prey risk assessment abilities.

    Directory of Open Access Journals (Sweden)

    Oona M Lönnstedt

    Full Text Available Invasive species cause catastrophic alterations to communities worldwide by changing the trophic balance within ecosystems. Ever since their introduction in the mid 1980's common red lionfish, Pterois volitans, are having dramatic impacts on the Caribbean ecosystem by displacing native species and disrupting food webs. Introduced lionfish capture prey at extraordinary rates, altering the composition of benthic communities. Here we demonstrate that the extraordinary success of the introduced lionfish lies in its capacity to circumvent prey risk assessment abilities as it is virtually undetectable by prey species in its native range. While experienced prey damselfish, Chromis viridis, respond with typical antipredator behaviours when exposed to a common predatory rock cod (Cephalopholis microprion they fail to visibly react to either the scent or visual presentation of the red lionfish, and responded only to the scent (not the visual cue of a lionfish of a different genus, Dendrochirus zebra. Experienced prey also had much higher survival when exposed to the two non-invasive predators compared to P. volitans. The cryptic nature of the red lionfish has enabled it to be destructive as a predator and a highly successful invasive species.

  4. Cellular automaton for migration in ecosystem: Application of traffic model to a predator-prey system

    Science.gov (United States)

    Nagatani, Takashi; Tainaka, Kei-ichi

    2018-01-01

    In most cases, physicists have studied the migration of biospecies by the use of random walk. In the present article, we apply cellular automaton of traffic model. For simplicity, we deal with an ecosystem contains a prey and predator, and use one-dimensional lattice with two layers. Preys stay on the first layer, but predators uni-directionally move on the second layer. The spatial and temporal evolution is numerically explored. It is shown that the migration has the important effect on populations of both prey and predator. Without migration, the phase transition between a prey-phase and coexisting-phase occurs. In contrast, the phase transition disappears by migration. This is because predator can survive due to migration. We find another phase transition for spatial distribution: in one phase, prey and predator form a stripe pattern of condensation and rarefaction, while in the other phase, they uniformly distribute. The self-organized stripe may be similar to the migration patterns in real ecosystems.

  5. Energetic conditions promoting top-down control of prey by predators.

    Directory of Open Access Journals (Sweden)

    Kristin N Marshall

    Full Text Available Humans remove large amounts of biomass from natural ecosystems, and large bodied high trophic level animals are especially sensitive and vulnerable to exploitation. The effects of removing top-predators on food webs are often difficult to predict because of limited information on species interaction strengths. Here we used a three species predator-prey model to explore relationships between energetic properties of trophodynamic linkages and interaction strengths to provide heuristic rules that indicate observable energetic conditions that are most likely to lead to stable and strong top-down control of prey by predator species. We found that strong top-down interaction strengths resulted from low levels of energy flow from prey to predators. Strong interactions are more stable when they are a consequence of low per capita predation and when predators are subsidized by recruitment. Diet composition also affects stability, but the relationship depends on the form of the functional response. Our results imply that for generalist satiating predators, strong top-down control on prey is most likely for prey items that occupy a small portion of the diet and when density dependent recruitment is moderately high.

  6. Artificial night light alters nocturnal prey interception outcomes for morphologically variable spiders.

    Science.gov (United States)

    Yuen, Suet Wai; Bonebrake, Timothy C

    2017-01-01

    Artificial night light has the potential to significantly alter visually-dependent species interactions. However, examples of disruptions of species interactions through changes in light remain rare and how artificial night light may alter predator-prey relationships are particularly understudied. In this study, we examined whether artificial night light could impact prey attraction and interception in Nephila pilipes orb weaver spiders, conspicuous predators who make use of yellow color patterns to mimic floral resources and attract prey to their webs. We measured moth prey attraction and interception responses to treatments where we experimentally manipulated the color/contrast of spider individuals in the field (removed yellow markings) and also set up light manipulations. We found that lit webs had lower rates of moth interception than unlit webs. Spider color, however, had no clear impact on moth interception or attraction rates in lit nor unlit webs. The results show that night light can reduce prey interception for spiders. Additionally, this study highlights how environmental and morphological variation can complicate simple predictions of ecological light pollution's disruption of species interactions.

  7. Foraging behavior and prey interactions by a guild of predators on various lifestages of Bemisia tabaci

    Directory of Open Access Journals (Sweden)

    James R. Hagler

    2004-01-01

    Full Text Available The sweetpotato whitefly, Bemisia tabaci (Gennadius is fed on by a wide variety of generalist predators, but there is little information on these predator-prey interactions. A laboratory investigation was conducted to quantify the foraging behavior of the adults of five common whitefly predators presented with a surfeit of whitefly eggs, nymphs, and adults. The beetles, Hippodamia convergens Guérin-Méneville and Collops vittatus (Say fed mostly on whitefly eggs, but readily and rapidly preyed on all of the whitefly lifestages. The true bugs, Geocoris punctipes (Say and Orius tristicolor (Say preyed almost exclusively on adult whiteflies, while Lygus hesperus Knight preyed almost exclusively on nymphs. The true bugs had much longer prey handling times than the beetles and spent much more of their time feeding (35-42% than the beetles (6-7%. These results indicate that generalist predators vary significantly in their interaction with this host, and that foraging behavior should be considered during development of a predator-based biological control program for B. tabaci.

  8. Infrared source test

    Energy Technology Data Exchange (ETDEWEB)

    Ott, L.

    1994-11-15

    The purpose of the Infrared Source Test (IRST) is to demonstrate the ability to track a ground target with an infrared sensor from an airplane. The system is being developed within the Advance Technology Program`s Theater Missile Defense/Unmanned Aerial Vehicle (UAV) section. The IRST payload consists of an Amber Radiance 1 infrared camera system, a computer, a gimbaled mirror, and a hard disk. The processor is a custom R3000 CPU board made by Risq Modular Systems, Inc. for LLNL. The board has ethernet, SCSI, parallel I/O, and serial ports, a DMA channel, a video (frame buffer) interface, and eight MBytes of main memory. The real-time operating system VxWorks has been ported to the processor. The application code is written in C on a host SUN 4 UNIX workstation. The IRST is the result of a combined effort by physicists, electrical and mechanical engineers, and computer scientists.

  9. Maximum sustainable yield and species extinction in a prey-predator system: some new results.

    Science.gov (United States)

    Ghosh, Bapan; Kar, T K

    2013-06-01

    Though the maximum sustainable yield (MSY) approach has been legally adopted for the management of world fisheries, it does not provide any guarantee against from species extinction in multispecies communities. In the present article, we describe the appropriateness of the MSY policy in a Holling-Tanner prey-predator system with different types of functional responses. It is observed that for both type I and type II functional responses, harvesting of either prey or predator species at the MSY level is a sustainable fishing policy. In the case of combined harvesting, both the species coexist at the maximum sustainable total yield (MSTY) level if the biotic potential of the prey species is greater than a threshold value. Further, increase of the biotic potential beyond the threshold value affects the persistence of the system.

  10. Simulation and analysis of a model dinoflagellate predator-prey system

    Science.gov (United States)

    Mazzoleni, M. J.; Antonelli, T.; Coyne, K. J.; Rossi, L. F.

    2015-12-01

    This paper analyzes the dynamics of a model dinoflagellate predator-prey system and uses simulations to validate theoretical and experimental studies. A simple model for predator-prey interactions is derived by drawing upon analogies from chemical kinetics. This model is then modified to account for inefficiencies in predation. Simulation results are shown to closely match the model predictions. Additional simulations are then run which are based on experimental observations of predatory dinoflagellate behavior, and this study specifically investigates how the predatory dinoflagellate Karlodinium veneficum uses toxins to immobilize its prey and increase its feeding rate. These simulations account for complex dynamics that were not included in the basic models, and the results from these computational simulations closely match the experimentally observed predatory behavior of K. veneficum and reinforce the notion that predatory dinoflagellates utilize toxins to increase their feeding rate.

  11. Bats without borders: Predators learn novel prey cues from other predatory species.

    Science.gov (United States)

    Patriquin, Krista J; Kohles, Jenna E; Page, Rachel A; Ratcliffe, John M

    2018-03-01

    Learning from others allows individuals to adapt rapidly to environmental change. Although conspecifics tend to be reliable models, heterospecifics with similar resource requirements may be suitable surrogates when conspecifics are few or unfamiliar with recent changes in resource availability. We tested whether Trachops cirrhosus , a gleaning bat that localizes prey using their mating calls, can learn about novel prey from conspecifics and the sympatric bat Lophostoma silvicolum. Specifically, we compared the rate for naïve T. cirrhosus to learn an unfamiliar tone from either a trained conspecific or heterospecific alone through trial and error or through social facilitation. T. cirrhosus learned this novel cue from L. silvicolum as quickly as from conspecifics. This is the first demonstration of social learning of a novel acoustic cue in bats and suggests that heterospecific learning may occur in nature. We propose that auditory-based social learning may help bats learn about unfamiliar prey and facilitate their adaptive radiation.

  12. A modified Leslie-Gower predator-prey interaction model and parameter identifiability

    Science.gov (United States)

    Tripathi, Jai Prakash; Meghwani, Suraj S.; Thakur, Manoj; Abbas, Syed

    2018-01-01

    In this work, bifurcation and a systematic approach for estimation of identifiable parameters of a modified Leslie-Gower predator-prey system with Crowley-Martin functional response and prey refuge is discussed. Global asymptotic stability is discussed by applying fluctuation lemma. The system undergoes into Hopf bifurcation with respect to parameters intrinsic growth rate of predators (s) and prey reserve (m). The stability of Hopf bifurcation is also discussed by calculating Lyapunov number. The sensitivity analysis of the considered model system with respect to all variables is performed which also supports our theoretical study. To estimate the unknown parameter from the data, an optimization procedure (pseudo-random search algorithm) is adopted. System responses and phase plots for estimated parameters are also compared with true noise free data. It is found that the system dynamics with true set of parametric values is similar to the estimated parametric values. Numerical simulations are presented to substantiate the analytical findings.

  13. Mammal predator and prey species richness are strongly linked at macroscales

    DEFF Research Database (Denmark)

    Sandom, Christopher James; Dalby, Lars; Fløjgaard, Camilla

    2013-01-01

    Predator–prey interactions play an important role for species composition and community dynamics at local scales, but their importance in shaping large-scale gradients of species richness remains unexplored. Here, we use global range maps, structural equation models (SEM), and comprehensive...... databases of dietary preferences and body masses of all terrestrial, non-volant mammals worldwide, to test whether (1) prey-bottom-up or predator- top-down relationships are important drivers of broad-scale species richness gradients once the environment and human influence has been accounted for, (2...... between them (e.g., large prey to small predators), suggesting that mass-related energetic and physiological constraints influence broad-scale richness links, especially for large-bodied mammals. Overall, our results support the idea that trophic interactions can be important drivers of large...

  14. Stochastic analysis of a pulse-type prey-predator model

    Science.gov (United States)

    Wu, Y.; Zhu, W. Q.

    2008-04-01

    A stochastic Lotka-Volterra model, a so-called pulse-type model, for the interaction between two species and their random natural environment is investigated. The effect of a random environment is modeled as random pulse trains in the birth rate of the prey and the death rate of the predator. The generalized cell mapping method is applied to calculate the probability distributions of the species populations at a state of statistical quasistationarity. The time evolution of the population densities is studied, and the probability of the near extinction time, from an initial state to a critical state, is obtained. The effects on the ecosystem behaviors of the prey self-competition term and of the pulse mean arrival rate are also discussed. Our results indicate that the proposed pulse-type model shows obviously distinguishable characteristics from a Gaussian-type model, and may confer a significant advantage for modeling the prey-predator system under discrete environmental fluctuations.

  15. Spotted hyaenas Crocuta crocuta prey on new-born elephant calves in Hwange National Park, Zimbabwe

    Directory of Open Access Journals (Sweden)

    Julia Salnicki

    2001-07-01

    Full Text Available Spotted hyaena Crocuta crocuta are known to be opportunists and to have a varied diet including mammals, reptiles and birds. Prey most often hunted are medium sized ungulates but spotted hyaenas will on occasion take larger species such as giraffe Giraffa camelopardalis and zebra Equus burchellii. They are also known to hunt whichever species are most abundant and will vary their prey seasonally. In this study spotted hyaenas were observed to take an unusual prey species in the form of elephant calves (Loxodonta africana. On a number of occasions hyaenas were observed feeding on or killing newborn and very young elephant calves. These observations were made whilst the authors were conducting research on spotted hyaena ecology in the woodlands of Hwange National Park, Zimbabwe and were made during the dry season between September and November 1999.

  16. Dynamics of a prey-predator system under Poisson white noise excitation

    Science.gov (United States)

    Pan, Shan-Shan; Zhu, Wei-Qiu

    2014-10-01

    The classical Lotka-Volterra (LV) model is a well-known mathematical model for prey-predator ecosystems. In the present paper, the pulse-type version of stochastic LV model, in which the effect of a random natural environment has been modeled as Poisson white noise, is investigated by using the stochastic averaging method. The averaged generalized Itô stochastic differential equation and Fokker-Planck-Kolmogorov (FPK) equation are derived for prey-predator ecosystem driven by Poisson white noise. Approximate stationary solution for the averaged generalized FPK equation is obtained by using the perturbation method. The effect of prey self-competition parameter ɛ2 s on ecosystem behavior is evaluated. The analytical result is confirmed by corresponding Monte Carlo (MC) simulation.

  17. Influence of local carrying capacity restrictions on stochastic predator-prey models

    International Nuclear Information System (INIS)

    Washenberger, Mark J; Mobilia, Mauro; Taeuber, Uwe C

    2007-01-01

    We study a stochastic lattice predator-prey system by means of Monte Carlo simulations that do not impose any restrictions on the number of particles per site, and discuss the similarities and differences of our results with those obtained for site-restricted model variants. In accord with the classic Lotka-Volterra mean-field description, both species always coexist in two dimensions. Yet competing activity fronts generate complex, correlated spatio-temporal structures. As a consequence, finite systems display transient erratic population oscillations with characteristic frequencies that are renormalized by fluctuations. For large reaction rates, when the processes are rendered more local, these oscillations are suppressed. In contrast with the site-restricted predator-prey model, we also observe species coexistence in one dimension. In addition, we report results on the steady-state prey age distribution

  18. Tadpoles of three common anuran species from Thailand do not prey on mosquito larvae.

    Science.gov (United States)

    Weterings, Robbie

    2015-12-01

    Tadpoles are often considered to be predators of mosquito larvae and are therefore beneficial for the control of certain disease vectors. Nevertheless, only a few species have actually been recorded to prey on mosquito larvae. The mosquito larvae predation rates of tadpoles of three common Thai anuran species (Bufo melanostictus, Kaloula pulchra and Hylarana raniceps) were experimentally tested. Tadpoles in varying developmental stages were used to assess a size/age effect on the predation rate. In addition, different instars of Culex quinquefasciatus were used in order to assess a prey size effect on the predation rates. All three species failed to show any evidence of mosquito larvae predation. Neither small nor large tadpoles fed on mosquito larvae. Prey size also did not affect predation. Although tadpoles do not feed on mosquito larvae, there may be other direct or indirect inter-specific interactions that adversely impact the development of larvae in shared habitats with tadpoles. © 2015 The Society for Vector Ecology.

  19. Prey and plastic ingestion of Pacific Northern Fulmars (Fulmarus glacialis rogersii) from Monterey Bay, California.

    Science.gov (United States)

    Donnelly-Greenan, Erica L; Harvey, James T; Nevins, Hannahrose M; Hester, Michelle M; Walker, William A

    2014-08-15

    Marine plastic pollution affects seabirds, including Pacific Northern Fulmars (Fulmarus glacialis rodgersii), that feed at the surface and mistake plastic for prey or incidentally ingest it. Direct and indirect health issues can result, including satiety and possibly leading to inefficient foraging. Our objective was to examine fulmar body condition, identify cephalopod diet to species, enumerate and weigh ingested plastic, and determine if prey number and size were correlated with ingested plastics in beach-cast fulmars wintering in Monterey Bay California (2003, n=178: 2007, n=185). Fulmars consumed mostly Gonatus pyros, G. onyx, and G. californiensis of similar size for both years. We found a significant negative correlation between pectoral muscle index and average size of cephalopod beaks per stomach; a significant increase in plastic categories between 2003 and 2007; and no significant correlation between number and mass of plastic compared with number and size of prey for either year. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Dynamical study of a chaotic predator-prey model with an omnivore

    Science.gov (United States)

    Al-khedhairi, A.; Elsadany, A. A.; Elsonbaty, A.; Abdelwahab, A. G.

    2018-01-01

    In this paper, the dynamics and bifurcations of a three-species predator-prey model with an omnivore are further investigated. The food web considered in this work comprises prey, predator and a third species, which consumes the carcasses of the predator along with predation of the original prey. The conditions for existence, uniqueness and continuous dependence on initial conditions for the solution of the model are derived. Analytical and numerical bifurcation studies reveal that the system undergoes transcritical and Hopf bifurcations around its equilibrium points. Further, the Hopf bifurcation curves in the parameters' space along with codimension two bifurcations of equilibrium points and bifurcation of limit cycles that arise in the system are investigated. In particular, the occurrence of generalized Hopf, fold Hopf and Neimarck-Sacker bifurcations is unveiled and illustrates the rich dynamics of the model. Finally, bifurcation diagrams, phase portraits and Lyapunov exponents of the model are presented.

  1. The threshold of coexistence and critical behaviour of a predator-prey cellular automaton

    International Nuclear Information System (INIS)

    Arashiro, Everaldo; Tome, Tania

    2007-01-01

    We study a probabilistic cellular automaton to describe two population biology problems: the threshold of species coexistence in a predator-prey system and the spreading of an epidemic in a population. By carrying out mean-field approximations and numerical simulations we obtain the phase boundaries (thresholds) related to the transition between an active state, where prey and predators present a stable coexistence, and a prey absorbing state. The numerical estimates for the critical exponents show that the transition belongs to the directed percolation universality class. In the limit where the cellular automaton maps into a model for the spreading of an epidemic with immunization we observe a crossover from directed percolation class to the dynamic percolation class. Patterns of growing clusters related to species coexistence and spreading of epidemic are shown and discussed

  2. Attracting predators without falling prey: chemical camouflage protects honeydew-producing treehoppers from ant predation.

    Science.gov (United States)

    Silveira, Henrique C P; Oliveira, Paulo S; Trigo, José R

    2010-02-01

    Predaceous ants are dominant organisms on foliage and represent a constant threat to herbivorous insects. The honeydew of sap-feeding hemipterans has been suggested to appease aggressive ants, which then begin tending activities. Here, we manipulated the cuticular chemical profiles of freeze-dried insect prey to show that chemical background matching with the host plant protects Guayaquila xiphias treehoppers against predaceous Camponotus crassus ants, regardless of honeydew supply. Ant predation is increased when treehoppers are transferred to a nonhost plant with which they have low chemical similarity. Palatable moth larvae manipulated to match the chemical background of Guayaquila's host plant attracted lower numbers of predatory ants than unchanged controls. Although aggressive tending ants can protect honeydew-producing hemipterans from natural enemies, they may prey on the trophobionts under shortage of alternative food resources. Thus chemical camouflage in G. xiphias allows the trophobiont to attract predaceous bodyguards at reduced risk of falling prey itself.

  3. Powerful infrared emitting diodes

    Directory of Open Access Journals (Sweden)

    Kogan L. M.

    2012-02-01

    Full Text Available Powerful infrared LEDs with emission wavelength 805 ± 10, 870 ± 20 and 940 ± 10 nm developed at SPC OED "OPTEL" are presented in the article. The radiant intensity of beam diode is under 4 W/sr in the continuous mode and under 100 W/sr in the pulse mode. The radiation power of wide-angle LEDs reaches 1 W in continuous mode. The external quantum efficiency of emission IR diodes runs up to 30%. There also has been created infrared diode modules with a block of flat Fresnel lenses with radiant intensity under 70 W/sr.

  4. Fine-scale tracking and diet information of a marine predator reveals the origin and contrasting spatial distribution of prey

    Science.gov (United States)

    Alonso, Hany; Granadeiro, José P.; Dias, Maria P.; Catry, Teresa; Catry, Paulo

    2018-03-01

    The distribution of many marine organisms is still poorly understood, particularly in oceanic regions. Seabirds, as aerial predators which cover extensive areas across the oceans, can potentially be used to enhance our knowledge on the distribution and abundance of their prey. In this study, we combined tracking data and dietary data from individual Cory's shearwaters Calonectris borealis (n = 68) breeding in Selvagens archipelago, Madeira, Portugal, during the chick-rearing periods of 2011 and 2016, in order to infer prey origin within shearwaters' main foraging areas. The digestion state of each prey item in the diet was assessed and classified; and compared to digestion states from known prey items fed to captive birds. In a novel approach, we combined tracking data with information on the prey digestion duration and data on the transit times from foraging grounds to the colony to estimate the location of prey capture. We found a consistent heterogeneity in prey distribution across four different marine domains: Selvagens, deep-sea, seamounts, and continental shelf. In oceanic areas, the chub mackerel Scomber colias, the main prey of Cory's shearwaters, was strongly associated with seamounts and insular shelves, whereas oceanic species like pilot-fish, flying-squid, flying-fish were clearly associated with deep-sea waters. Sardines Sardina pilchardus, anchovies Engraulis encrasicolus and other coastal species were associated with the African shelf. Prey origin assignment was robust across three different sets of assumptions, and was also supported by information on the digestion state of prey collected over a large independent sampling period (671 samples, collected in 2008-2010). The integration of fine-scale dietary and foraging trip data from marine predators provides a new framework to gain insights into the distribution and abundance of prey species in poorly known oceanic areas.

  5. Australian fur seals (Arctocephalus pusillus doriferus use raptorial biting and suction feeding when targeting prey in different foraging scenarios.

    Directory of Open Access Journals (Sweden)

    David P Hocking

    Full Text Available Foraging behaviours used by two female Australian fur seals (Arctocephalus pusillus doriferus were documented during controlled feeding trials. During these trials the seals were presented with prey either free-floating in open water or concealed within a mobile ball or a static box feeding device. When targeting free-floating prey both subjects primarily used raptorial biting in combination with suction, which was used to draw prey to within range of the teeth. When targeting prey concealed within either the mobile or static feeding device, the seals were able to use suction to draw out prey items that could not be reached by biting. Suction was followed by lateral water expulsion, where water drawn into the mouth along with the prey item was purged via the sides of the mouth. Vibrissae were used to explore the surface of the feeding devices, especially when locating the openings in which the prey items had been hidden. The mobile ball device was also manipulated by pushing it with the muzzle to knock out concealed prey, which was not possible when using the static feeding device. To knock prey out of this static device one seal used targeted bubble blowing, where a focused stream of bubbles was blown out of the nose into the openings in the device. Once captured in the jaws, prey items were manipulated and re-oriented using further mouth movements or chews so that they could be swallowed head first. While most items were swallowed whole underwater, some were instead taken to the surface and held in the teeth, while being vigorously shaken to break them into smaller pieces before swallowing. The behavioural flexibility displayed by Australian fur seals likely assists in capturing and consuming the extremely wide range of prey types that are targeted in the wild, during both benthic and epipelagic foraging.

  6. Effects of allochthonous inputs in the control of infectious disease of prey

    International Nuclear Information System (INIS)

    Sahoo, Banshidhar; Poria, Swarup

    2015-01-01

    Highlights: •Infected predator–prey model with allochthonous inputs is proposed. •Stability and persistence conditions are derived. •Bifurcation is determined with respect to allochthonous inputs. •Results show that system can not be disease free without allochthonous inputs. •Hopf and its continuation bifurcation is analysed numerically. -- Abstract: Allochthonous inputs are important sources of productivity in many food webs and their influences on food chain model demand further investigations. In this paper, assuming the existence of allochthonous inputs for intermediate predator, a food chain model is formulated with disease in the prey. The stability and persistence conditions of the equilibrium points are determined. Extinction criterion for infected prey population is obtained. It is shown that suitable amount of allochthonous inputs to intermediate predator can control infectious disease of prey population, provided initial intermediate predator population is above a critical value. This critical intermediate population size increases monotonically with the increase of infection rate. It is also shown that control of infectious disease of prey is possible in some cases of seasonally varying contact rate. Dynamical behaviours of the model are investigated numerically through one and two parameter bifurcation analysis using MATCONT 2.5.1 package. The occurrence of Hopf and its continuation curves are noted with the variation of infection rate and allochthonous food availability. The continuation curves of limit point cycle and Neimark Sacker bifurcation are drawn by varying the rate of infection and allochthonous inputs. This study introduces a novel natural non-toxic method for controlling infectious disease of prey in a food chain model

  7. Group-specific multiplex PCR detection systems for the identification of flying insect prey.

    Directory of Open Access Journals (Sweden)

    Daniela Sint

    Full Text Available The applicability of species-specific primers to study feeding interactions is restricted to those ecosystems where the targeted prey species occur. Therefore, group-specific primer pairs, targeting higher taxonomic levels, are often desired to investigate interactions in a range of habitats that do not share the same species but the same groups of prey. Such primers are also valuable to study the diet of generalist predators when next generation sequencing approaches cannot be applied beneficially. Moreover, due to the large range of prey consumed by generalists, it is impossible to investigate the breadth of their diet with species-specific primers, even if multiplexing them. However, only few group-specific primers are available to date and important groups of prey such as flying insects have rarely been targeted. Our aim was to fill this gap and develop group-specific primers suitable to detect and identify the DNA of common taxa of flying insects. The primers were combined in two multiplex PCR systems, which allow a time- and cost-effective screening of samples for DNA of the dipteran subsection Calyptratae (including Anthomyiidae, Calliphoridae, Muscidae, other common dipteran families (Phoridae, Syrphidae, Bibionidae, Chironomidae, Sciaridae, Tipulidae, three orders of flying insects (Hymenoptera, Lepidoptera, Plecoptera and coniferous aphids within the genus Cinara. The two PCR assays were highly specific and sensitive and their suitability to detect prey was confirmed by testing field-collected dietary samples from arthropods and vertebrates. The PCR assays presented here allow targeting prey at higher taxonomic levels such as family or order and therefore improve our ability to assess (trophic interactions with flying insects in terrestrial and aquatic habitats.

  8. Predator-prey dynamics driven by feedback between functionally diverse trophic levels.

    Directory of Open Access Journals (Sweden)

    Katrin Tirok

    Full Text Available Neglecting the naturally existing functional diversity of communities and the resulting potential to respond to altered conditions may strongly reduce the realism and predictive power of ecological models. We therefore propose and study a predator-prey model that describes mutual feedback via species shifts in both predator and prey, using a dynamic trait approach. Species compositions of the two trophic levels were described by mean functional traits--prey edibility and predator food-selectivity--and functional diversities by the variances. Altered edibility triggered shifts in food-selectivity so that consumers continuously respond to the present prey composition, and vice versa. This trait-mediated feedback mechanism resulted in a complex dynamic behavior with ongoing oscillations in the mean trait values, reflecting continuous reorganization of the trophic levels. The feedback was only possible if sufficient functional diversity was present in both trophic levels. Functional diversity was internally maintained on the prey level as no niche existed in our system, which was ideal under any composition of the predator level due to the trade-offs between edibility, growth and carrying capacity. The predators were only subject to one trade-off between food-selectivity and grazing ability and in the absence of immigration, one predator type became abundant, i.e., functional diversity declined to zero. In the lack of functional diversity the system showed the same dynamics as conventional models of predator-prey interactions ignoring the potential for shifts in species composition. This way, our study identified the crucial role of trade-offs and their shape in physiological and ecological traits for preserving diversity.

  9. Arthropod prey for riparian associated birds in headwater forests of the Oregon Coast Range

    Science.gov (United States)

    Hagar, Joan C.; Li, Judith; Sobota, Janel; Jenkins, Stephanie

    2012-01-01

    Headwater riparian areas occupy a large proportion of the land base in Pacific Northwest forests, and thus are ecologically and economically important. Although a primary goal of management along small headwater streams is the protection of aquatic resources, streamside habitat also is important for many terrestrial wildlife species. However, mechanisms underlying the riparian associations of some terrestrial species have not been well studied, particularly for headwater drainages. We investigated the diets of and food availability for four bird species associated with riparian habitats in montane coastal forests of western Oregon, USA. We examined variation in the availability of arthropod prey as a function of distance from stream. Specifically, we tested the hypotheses that (1) emergent aquatic insects were a food source for insectivorous birds in headwater riparian areas, and (2) the abundances of aquatic and terrestrial arthropod prey did not differ between streamside and upland areas during the bird breeding season. We found that although adult aquatic insects were available for consumption throughout the study period, they represented a relatively small proportion of available prey abundance and biomass and were present in only 1% of the diet samples from only one of the four riparian-associated bird species. Nonetheless, arthropod prey, comprised primarily of insects of terrestrial origin, was more abundant in streamside than upland samples. We conclude that food resources for birds in headwater riparian areas are primarily associated with terrestrial vegetation, and that bird distributions along the gradient from streamside to upland may be related to variation in arthropod prey availability. Because distinct vegetation may distinguish riparian from upland habitats for riparian-associated birds and their terrestrial arthropod prey, we suggest that understory communities be considered when defining management zones for riparian habitat.

  10. Predators and resources influence phosphorus transfer along an invertebrate food web through changes in prey behaviour.

    Directory of Open Access Journals (Sweden)

    Edoardo Calizza

    Full Text Available Predators play a fundamental role in prey trophic behaviour, with indirect consequences for species coexistence and ecosystem functioning. Resource quality and availability also influence prey trophic behaviour, with potential effects on predator-prey dynamics. Although many studies have addressed these topics, little attention has been paid to the combined effects of predators and resources on prey species coexistence and nutrient transfer along food chains, especially in detritus-based systems. To determine the influence of predators and resource quality on the movement and P uptake of detritivores, we carried out a field experiment on the River Kelvin (Scotland using (32P to test the hypothesis of reduced prey vagility among resource patches as a strategy to avoid predation. Thirty leaf sacks containing alder leaves and two detritivore prey populations (Asellus aquaticus and Lymnaea peregra were placed in cages, half of them with two predator species (Dendrocoelum lacteum and Erpobdella octoculata and the other half without predators. Five alder leaf bags, each individually inoculated with a different fungus strain to simulate a patchy habitat, were placed inside each leaf sack. One bag in each sack was labelled with (32P, in order to assess the proportion of detritivores using it as food and thus their movement among the five resource patches. Three replicates for each labelled fungus and each predation treatment (i.e. with and without predators were left on the riverbed for 7 days. The presence of predators had negligible effects on the number of detritivores in the leaf bags, but it did reduce the proportion of (32P-labelled detritivores and their P uptake. The most strongly affected species was A. aquaticus, whose vagility, trophic overlap with L. peregra and P uptake were all reduced. The results confirm the importance of bottom-up and top-down forces acting simultaneously to regulate nutrient transfer along food chains in patchy

  11. Bio-Physical Coupling of Seabirds and Prey with a Dynamic River Plume

    Science.gov (United States)

    Phillips, E. M.; Horne, J. K.; Zamon, J. E.; Adams, J.

    2016-02-01

    Freshwater plumes and plume density fronts are important regions of bio-physical coupling. On the west coast of North America, discharge from the Columbia River into the northern California Current creates a large, dynamic plume and multiple plume fronts. These nutrient-rich, productive waters fuel primary and secondary production, supporting a wide variety of small pelagic prey fish, large populations of Pacific salmon, seabirds, and marine mammals. To determine the influence of the Columbia River plume on marine predators, we analyzed at-sea seabird counts, in situ environmental data, surface trawl densities of prey fish, and acoustic backscatter measurements collected from research vessels in May and June 2010-2012. Concurrent distribution patterns of satellite-tagged sooty shearwaters (Puffinus griseus) and common murres (Uria aalge) were compared with seabird counts from ship surveys. To evaluate plume use by satellite-tagged birds, daily surface salinity values from SELFE hindcast models were extracted at each tag location. Both seabird species occurred in plume waters disproportionate to the total surveyed area, concentrating in the river plume when river flow and plume volume decreased. Murres were consistently within 20 km of the geographic mean center of the river plume. In contrast, shearwaters consistently occurred 100 km to the north of the plume center, where high densities of prey fish occur. Although acoustically detected prey also occurred in greater densities within the plume when volume decreased, surface catches of prey in the plume did not vary with changing plume conditions. Geographic indices of colocation (GIC) were low between murres and prey species caught in surface trawls, whereas GICs were >0.5 between shearwaters and prey species including squid (Loligo opalescens), juvenile Chinook salmon (Oncorhynchus tshawytscha), and coho (O. kisutch) salmon. We conclude that the river plume and associated fronts are identifiable, predictable, and

  12. The effect of water level in a prey-predator interactions: A nonlinear analysis study

    International Nuclear Information System (INIS)

    Chiboub Fellah, N.; Bouguima, S.M.; Moussaoui, A.

    2012-01-01

    Highlights: ► A new model describing the interaction between predator and prey in Parloup Lake. ► Existence of periodic solution is proved. ► Seasonal variation in water level is an important factor for persitence. - Abstract: Water level may influence local community dynamics. We examine how seasonal variations in water level affect the outcome of prey-predator interactions in Parloup Lake in the south of France. We propose a new model to describe the annual cycle of persistence by using continuation theorem of coincidence degree.

  13. The dynamical complexity of a Ivlev-type prey-predator system with impulsive effect

    International Nuclear Information System (INIS)

    Wang Hailing; Wang Weiming

    2008-01-01

    Based on the classical predator-prey system with Ivlev-type functional response, an impulsive differential equations to model the process of periodic perturbations on the predator at different fixed time is established. It proves that there exists a locally asymptotically stable prey-eradication periodic solution when the impulse period is less than some critical value, and otherwise, the system can be permanent. Numerical results show that the system considered has more complicated dynamics. such as quasi-periodic oscillation, narrow periodic window, wide periodic window, chaotic bands, symmetry-breaking pitchfork bifurcation and crises, etc

  14. Rank One Strange Attractors in Periodically Kicked Predator-Prey System with Time-Delay

    Science.gov (United States)

    Yang, Wenjie; Lin, Yiping; Dai, Yunxian; Zhao, Huitao

    2016-06-01

    This paper is devoted to the study of the problem of rank one strange attractor in a periodically kicked predator-prey system with time-delay. Our discussion is based on the theory of rank one maps formulated by Wang and Young. Firstly, we develop the rank one chaotic theory to delayed systems. It is shown that strange attractors occur when the delayed system undergoes a Hopf bifurcation and encounters an external periodic force. Then we use the theory to the periodically kicked predator-prey system with delay, deriving the conditions for Hopf bifurcation and rank one chaos along with the results of numerical simulations.

  15. Comparative analysis of marine ecosystems: workshop on predator-prey interactions

    DEFF Research Database (Denmark)

    Bailey, Kevin M.; Ciannelli, Lorenzo; Hunsicker, Mary

    2010-01-01

    in marine ecosystems was held at the Oregon State University, Corvallis, OR, USA on 16–18 March 2010. The meeting brought together scientists from diverse fields of expertise including theoretical ecology, animal behaviour, fish and seabird ecology, statistics, fisheries science and ecosystem modelling......Climate and human influences on marine ecosystems are largely manifested by changes in predator–prey interactions. It follows that ecosystem-based management of the world's oceans requires a better understanding of food web relationships. An international workshop on predator–prey interactions...

  16. The interplay among prey preference, nutrient enrichment and stability in an omnivory system

    Directory of Open Access Journals (Sweden)

    LDB. Faria

    Full Text Available Food webs usually display an intricate mix of trophic interactions where multiple prey are common. In this context omnivory has been the subject of intensive analysis regarding food web stability and structure. In a three species omnivory setting it is shown that the modeling of prey preference by the top predator may exert a strong influence on the short as well as on the long term dynamics of the respective food web. Clearly, this has implications concerning the stability and the structure of omnivory systems under disturbances such as nutrient enrichment.

  17. Traveling waves in a diffusive predator-prey model with holling type-III functional response

    International Nuclear Information System (INIS)

    Li Wantong; Wu Shiliang

    2008-01-01

    We establish the existence of traveling wave solutions and small amplitude traveling wave train solutions for a reaction-diffusion system based on a predator-prey model with Holling type-III functional response. The analysis is in the three-dimensional phase space of the nonlinear ordinary differential equation system given by the diffusive predator-prey system in the traveling wave variable. The methods used to prove the results are the shooting argument, invariant manifold theory and the Hopf bifurcation theorem

  18. Attack or attacked: The sensory and fluid mechanical constraints of copepods’ predator–prey interactions

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2013-01-01

    , and mechanisms for mobility of the parties involved. Here, I describe the mechanisms of sensing, escaping predators, and capturing prey in marine pelagic copepods. I demonstrate that feeding tradeoffs vary with feeding mode, and I describe simple fluid mechanical models that are used to quantify these tradeoffs......Many animals are predator and prey at the same time. This dual position represents a fundamental dilemma because gathering food often leads to increased exposure to predators. The optimization of the tradeoff between eating and not being eaten depends strongly on the sensing, feeding...

  19. Chaos in periodically forced Holling type II predator-prey system with impulsive perturbations

    International Nuclear Information System (INIS)

    Zhang Shuwen; Tan Dejun; Chen Lansun

    2006-01-01

    The effect of periodic forcing and impulsive perturbations on predator-prey model with Holling type II functional response is investigated. The periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of prey. The impulsive perturbation is affected by introducing periodic constant impulsive immigration of predator. The dynamical behavior of the system is simulated and bifurcation diagrams are obtained for different parameters. The results show that periodic forcing and impulsive perturbation can very easily give rise to complex dynamics, including (1) quasi-periodic oscillating, (2) period doubling cascade, (3) chaos, (4) period halfing cascade, (5) non-unique dynamics

  20. Chaos in periodically forced Holling type IV predator-prey system with impulsive perturbations

    International Nuclear Information System (INIS)

    Zhang Shuwen; Tan Dejun; Chen Lansun

    2006-01-01

    The effect of periodic forcing and impulsive perturbations on predator-prey model with Holling type IV functional response is investigated. The periodic forcing is affected by assuming a periodic variation in the intrinsic growth rate of the prey. The impulsive perturbations are affected by introducing periodic constant impulsive immigration of predator. The dynamical behavior of the system is simulated and bifurcation diagrams are obtained for different parameters. The results show that periodic forcing and impulsive perturbation can easily give rise to complex dynamics, including (1) quasi-periodic oscillating, (2) period doubling cascade, (3) chaos, (4) period halfing cascade