Differential wolf-pack-size persistence and the role of risk when hunting dangerous prey

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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.

High risk of lead contamination for scavengers in an area with high moose hunting success.

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Legagneux, Pierre; Suffice, Pauline; Messier, Jean-Sébastien; Lelievre, Frédérick; Tremblay, Junior A; Maisonneuve, Charles; Saint-Louis, Richard; Bêty, Joël

2014-01-01

Top predators and scavengers are vulnerable to pollutants, particularly those accumulated along the food chain. Lead accumulation can induce severe disorders and alter survival both in mammals (including humans) and in birds. A potential source of lead poisoning in wild animals, and especially in scavengers, results from the consumption of ammunition residues in the tissues of big game killed by hunters. For two consecutive years we quantified the level lead exposure in individuals of a sentinel scavenger species, the common raven (Corvus corax), captured during the moose (Alces alces) hunting season in eastern Quebec, Canada. The source of the lead contamination was also determined using stable isotope analyses. Finally, we identified the different scavenger species that could potentially be exposed to lead by installing automatic cameras targeting moose gut piles. Blood lead concentration in ravens increased over time, indicating lead accumulation over the moose-hunting season. Using a contamination threshold of 100 µg x L(-1), more than 50% of individuals were lead-contaminated during the moose hunting period. Lead concentration was twice as high in one year compared to the other, matching the number of rifle-shot moose in the area. Non-contaminated birds exhibited no ammunition isotope signatures. The isotope signature of the lead detected in contaminated ravens tended towards the signature from lead ammunition. We also found that black bears (Ursus americanus), golden eagles and bald eagles (Aquila chrysaetos and Haliaeetus leucocephalus, two species of conservation concern) scavenged heavily on moose viscera left by hunters. Our unequivocal results agree with other studies and further motivate the use of non-toxic ammunition for big game hunting.

High risk of lead contamination for scavengers in an area with high moose hunting success.

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Pierre Legagneux

Full Text Available Top predators and scavengers are vulnerable to pollutants, particularly those accumulated along the food chain. Lead accumulation can induce severe disorders and alter survival both in mammals (including humans and in birds. A potential source of lead poisoning in wild animals, and especially in scavengers, results from the consumption of ammunition residues in the tissues of big game killed by hunters. For two consecutive years we quantified the level lead exposure in individuals of a sentinel scavenger species, the common raven (Corvus corax, captured during the moose (Alces alces hunting season in eastern Quebec, Canada. The source of the lead contamination was also determined using stable isotope analyses. Finally, we identified the different scavenger species that could potentially be exposed to lead by installing automatic cameras targeting moose gut piles. Blood lead concentration in ravens increased over time, indicating lead accumulation over the moose-hunting season. Using a contamination threshold of 100 µg x L(-1, more than 50% of individuals were lead-contaminated during the moose hunting period. Lead concentration was twice as high in one year compared to the other, matching the number of rifle-shot moose in the area. Non-contaminated birds exhibited no ammunition isotope signatures. The isotope signature of the lead detected in contaminated ravens tended towards the signature from lead ammunition. We also found that black bears (Ursus americanus, golden eagles and bald eagles (Aquila chrysaetos and Haliaeetus leucocephalus, two species of conservation concern scavenged heavily on moose viscera left by hunters. Our unequivocal results agree with other studies and further motivate the use of non-toxic ammunition for big game hunting.

Reproduction in moose at their southern range limit

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Ruprecht, Joel S.; Hersey, Kent R.; Hafen, Konrad; Monteith, Kevin L.; DeCesare, Nicholas J.; Kauffman, Matthew J.; MacNulty, Daniel R.

2016-01-01

Reproduction is a critical fitness component in large herbivores. Biogeographic models predict that populations occurring at the edges of the range may have compromised reproductive rates because of inferior habitat at range peripheries. When reproductive rates are chronically low, ungulate populations may lack the resiliency to rebound quickly after periods of environmental stress, and this effect may be greatest for heat-sensitive organisms at their southern range limit. To assess the demographic vulnerability of moose ( Alces alces ), we studied relationships between reproductive rates, maternal age, and rump fat in the southernmost naturally occurring moose population in North America. For prime-aged moose in our study, pregnancy rates were high (92%), but moose aged 9 years had low pregnancy rates (32% and 38%, respectively). The relationship between rump fat and pregnancy was nonlinear such that a threshold of at least 2mm of rump fat yielded a high probability of being pregnant midwinter. In contrast, among pregnant moose, the probability of both producing a calf and recruiting it until spring increased linearly with rump fat. We also conducted a meta-analysis of pregnancy and twinning rates for adult (≥ 2 years) moose across a latitudinal gradient to compare reproductive rates from our study to other populations in North America. Moose living at southern latitudes tended to have lower reproductive rates than those living in the core of moose range, implying that southern moose populations may be demographically more vulnerable than northern moose populations.

Hematology and serum chemistry reference ranges of free-ranging moose (Alces alces) in Norway.

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Rostal, Melinda K; Evans, Alina L; Solberg, Erling J; Arnemo, Jon M

2012-07-01

Baseline reference ranges of serum chemistry and hematology data can be important indicators for the status of both individuals or populations of wild animals that are affected by emerging pathogens, toxicants, or other causes of disease. Frequently, reference ranges for these values are not available for wildlife species or subspecies. We present hematologic and serum chemistry reference ranges for moose (Alces alces) adults, yearlings, and calves in Norway sampled from 1992-2000. Additionally, we demonstrated that both induction time and chase time were correlated with initial rectal temperature, although they were not significantly correlated with cortisol, aspartate aminotransferase, glucose, or creatine kinase. Overall, the reference ranges given here are similar to those given for American moose, with a few differences that can be attributed to environment, testing methodology, or subspecies or species status. This is the first report, to our knowledge, of reference ranges for moose in Norway.

Response of moose to a high‐density road network

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Wattles, David W.; Zeller, Katherine A.; DeStefano, Stephen

2018-01-01

Road networks and the disturbance associated with vehicle traffic alter animal behavior, movements, and habitat selection. The response of moose (Alces americanus) to roads has been documented in relatively rural areas, but less is known about moose response to roads in more highly roaded landscapes. We examined road‐crossing frequencies and habitat use of global positioning system (GPS)‐collared moose in Massachusetts, USA, where moose home ranges have road densities approximately twice that of previous studies. We compared seasonal road‐crossing frequencies of moose with a null movement model. We estimated moose travel speeds during road‐crossing events and compared them with speeds during other home range movements. To estimate the extent of the road effect zone and determine how roads influenced moose habitat use, we fit a third‐order resource selection function. With the exception of the lowest use road class (roads less than expected based on the null movement model and frequency decreased with increasing road size and traffic. Moose crossed roads faster than they traveled during other times. This effect increased with increasing road use intensity. Overall, roads were a major factor determining what portions of Massachusetts moose used and how they moved among habitat patches. Our results suggest that moose in Massachusetts can adapt to a high‐density road network, but the road effect is still strongly negative and, in some cases, is more pronounced than in study areas with lower road densities. Future road construction and the expansion of road networks may have a large effect on moose and other wildlife.

Prey detection and prey capture in copepod nauplii.

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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.

Maximum sustainable yield and species extinction in a prey-predator system: some new results.

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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.

A SNP resource for studying North American moose [version 1; referees: 2 approved, 1 approved with reservations

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Theodore S. Kalbfleisch

2018-01-01

Full Text Available Background: Moose (Alces alces colonized the North American continent from Asia less than 15,000 years ago, and spread across the boreal forest regions of Canada and the northern United States (US.  Contemporary populations have low genetic diversity, due either to low number of individuals in the original migration (founder effect, and/or subsequent population bottlenecks in North America.  Genetic tests based on informative single nucleotide polymorphism (SNP markers are helpful in forensic and wildlife conservation activities, but have been difficult to develop for moose, due to the lack of a reference genome assembly and whole genome sequence (WGS data. Methods:  WGS data were generated for four individual moose from the US states of Alaska, Idaho, Wyoming, and Vermont with minimum and average genome coverage depths of 14- and 19-fold, respectively.  Cattle and sheep reference genomes were used for aligning sequence reads and identifying moose SNPs. Results:  Approximately 11% and 9% of moose WGS reads aligned to cattle and sheep genomes, respectively.  The reads clustered at genomic segments, where sequence identity between these species was greater than 95%.  In these segments, average mapped read depth was approximately 19-fold.  Sets of 46,005 and 36,934 high-confidence SNPs were identified from cattle and sheep comparisons, respectively, with 773 and 552 of those having minor allele frequency of 0.5 and conserved flanking sequences in all three species.  Among the four moose, heterozygosity and allele sharing of SNP genotypes were consistent with decreasing levels of moose genetic diversity from west to east.  A minimum set of 317 SNPs, informative across all four moose, was selected as a resource for future SNP assay design. Conclusions:  All SNPs and associated information are available, without restriction, to support development of SNP-based tests for animal identification, parentage determination, and estimating

Moose models with vanishing S parameter

International Nuclear Information System (INIS)

Casalbuoni, R.; De Curtis, S.; Dominici, D.

2004-01-01

In the linear moose framework, which naturally emerges in deconstruction models, we show that there is a unique solution for the vanishing of the S parameter at the lowest order in the weak interactions. We consider an effective gauge theory based on K SU(2) gauge groups, K+1 chiral fields, and electroweak groups SU(2) L and U(1) Y at the ends of the chain of the moose. S vanishes when a link in the moose chain is cut. As a consequence one has to introduce a dynamical nonlocal field connecting the two ends of the moose. Then the model acquires an additional custodial symmetry which protects this result. We examine also the possibility of a strong suppression of S through an exponential behavior of the link couplings as suggested by the Randall Sundrum metric

A Unique Fatal Moose Attack Mimicking Homicide.

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Gudmannsson, Petur; Berge, Johan; Druid, Henrik; Ericsson, Göran; Eriksson, Anders

2018-03-01

Fatalities caused by animal attacks are rare, but have the potential to mimic homicide. We present a case in which a moose attacked and killed a woman who was walking her dog in a forest. Autopsy showed widespread blunt trauma with a large laceration on one leg in which blades of grass were embedded. Flail chest was the cause of death. The case was initially conceived as homicide by means of a riding lawn mower. A review of the case by moose experts and analyses of biological trace material that proved to originate from moose, established the true source of injury. The dog probably provoked a moose, which, in response, stomped and gored the victim to death. The injuries resembled those previously reported from attacks by cattle and water buffalo. Fatal moose attacks constitute an extremely rare threat in boreal areas, but can be considered in traumatic deaths of unknown cause. © 2017 American Academy of Forensic Sciences.

Range Expansion of Moose in Arctic Alaska Linked to Warming and Increased Shrub Habitat.

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Ken D Tape

Full Text Available Twentieth century warming has increased vegetation productivity and shrub cover across northern tundra and treeline regions, but effects on terrestrial wildlife have not been demonstrated on a comparable scale. During this period, Alaskan moose (Alces alces gigas extended their range from the boreal forest into tundra riparian shrub habitat; similar extensions have been observed in Canada (A. a. andersoni and Eurasia (A. a. alces. Northern moose distribution is thought to be limited by forage availability above the snow in late winter, so the observed increase in shrub habitat could be causing the northward moose establishment, but a previous hypothesis suggested that hunting cessation triggered moose establishment. Here, we use recent changes in shrub cover and empirical relationships between shrub height and growing season temperature to estimate available moose habitat in Arctic Alaska c. 1860. We estimate that riparian shrubs were approximately 1.1 m tall c. 1860, greatly reducing the available forage above the snowpack, compared to 2 m tall in 2009. We believe that increases in riparian shrub habitat after 1860 allowed moose to colonize tundra regions of Alaska hundreds of kilometers north and west of previous distribution limits. The northern shift in the distribution of moose, like that of snowshoe hares, has been in response to the spread of their shrub habitat in the Arctic, but at the same time, herbivores have likely had pronounced impacts on the structure and function of these shrub communities. These northward range shifts are a bellwether for other boreal species and their associated predators.

Range expansion of moose in arctic Alaska linked to warming and increased shrub habitat

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Tape, Ken D.; Gustine, David D.; Reuss, Roger W.; Adams, Layne G.; Clark, Jason A.

2016-01-01

Twentieth century warming has increased vegetation productivity and shrub cover across northern tundra and treeline regions, but effects on terrestrial wildlife have not been demonstrated on a comparable scale. During this period, Alaskan moose (Alces alces gigas) extended their range from the boreal forest into tundra riparian shrub habitat; similar extensions have been observed in Canada (A. a. andersoni) and Eurasia (A. a. alces). Northern moose distribution is thought to be limited by forage availability above the snow in late winter, so the observed increase in shrub habitat could be causing the northward moose establishment, but a previous hypothesis suggested that hunting cessation triggered moose establishment. Here, we use recent changes in shrub cover and empirical relationships between shrub height and growing season temperature to estimate available moose habitat in Arctic Alaska c. 1860. We estimate that riparian shrubs were approximately 1.1 m tall c. 1860, greatly reducing the available forage above the snowpack, compared to 2 m tall in 2009. We believe that increases in riparian shrub habitat after 1860 allowed moose to colonize tundra regions of Alaska hundreds of kilometers north and west of previous distribution limits. The northern shift in the distribution of moose, like that of snowshoe hares, has been in response to the spread of their shrub habitat in the Arctic, but at the same time, herbivores have likely had pronounced impacts on the structure and function of these shrub communities. These northward range shifts are a bellwether for other boreal species and their associated predators.

Monitoring Forsmark. Moose age composition, reproduction and antler development in Haallnaes

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Cederlund, Goeran; Broman, Emil

2011-05-01

The moose (Alces alces) is an important game species in Haallnaes, as well as in Sweden in general. Hunting on moose is subject to strict local regulations and restrictions within a management program. Such restrictions will have considerable effects on demography. This has led to a moose population in Haallnaes with biased sex ratio with fewer adult males than females and a generally low average age. High hunting pressure on males has caused a low survival rate and the chance to survive more than five years is just a few percent. Restrictions in hunting pressure on females have caused a generally higher survival rate and a higher average age compared to males. Sex differences in body mass are normal compared to other populations in southern Sweden. Mean body mass of culled calves is an important measure of quality of the population, since it reflects the available food resources in the management area. Body mass among calves in Haallnaes is generally low, indicating a deteriorated food resource due to either ambient population density and/or hampered food production in the forest. The average reproduction rate is normal compared to other populations in this part of Sweden. However, one year old females (yearlings) have a fairly low production of eggs per female (ovulation rate). As the yearlings constitute a considerable part of the population in Haallnaes, their lowered ovulation rate will affect the rate of recruitment of calves to the local population. The moose population seems to have been subject to considerable variation in density during the last decade, which is probably a joint effect of changes in demography (hunting), changes in food resources due to forestry management and by food competition from other browsers in the area. Local managers believe that the population has reached such a low level (although not verified by surveys) that the number of moose has to be increased. It is vital to stress the importance of keeping up collection of data from

Monitoring Forsmark. Moose age composition, reproduction and antler development in Forsmark

International Nuclear Information System (INIS)

Cederlund, Goeran; Broman, Emil

2011-05-01

The moose (Alces alces) is an important game species in Forsmark, as well as in Sweden in general. Hunting on moose is subject to strict local regulations and restrictions within a management program. Such restrictions will have considerable effects on demography. This has led to a moose population in Forsmark with biased sex ratio with fewer adult males than females and a generally low average age. High hunting pressure on males has caused a low survival rate and the chance to survive more than five years is just a few percent. Restrictions in hunting pressure on females have caused a generally higher survival rate and a higher average age compared to males. Sex differences in body mass are normal compared to other populations in southern Sweden. Mean body mass of culled calves is an important measure of quality of the population, since it reflects the available food resources in the management area. Body mass among calves in Forsmark is generally low, indicating a deteriorated food resource due to either ambient population density and/or hampered food production in the forest. The average reproduction rate is normal compared to other populations in this part of Sweden. However, one year old females (yearlings) have a fairly low production of eggs per female (ovulation rate). As the yearlings constitute a considerable part of the population in Forsmark, their lowered ovulation rate will affect the rate of recruitment of calves to the local population. The moose population seems to have been subject to considerable variation in density during the last decade, which is probably a joint effect of changes in demography (hunting), changes in food resources due to forestry management and by food competition from other browsers in the area. Local managers believe that the population has reached such a low level (although not verified by surveys) that the number of moose has to be increased. It is vital to stress the importance of keeping up collection of data from the

Tadpoles of three common anuran species from Thailand do not prey on mosquito larvae.

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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.

Wolves on the hunt: The behavior of wolves hunting wild prey

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Mech, L. David; Smith, Douglas W.; MacNulty, Daniel R.

2015-01-01

The interactions between apex predators and their prey are some of the most awesome and meaningful in nature—displays of strength, endurance, and a deep coevolutionary history. And there is perhaps no apex predator more impressive and important in its hunting—or more infamous, more misjudged—than the wolf. Because of wolves’ habitat, speed, and general success at evading humans, researchers have faced great obstacles in studying their natural hunting behaviors. The first book to focus explicitly on wolf hunting of wild prey, Wolves on the Hunt seeks to fill these gaps in our knowledge and understanding. Combining behavioral data, thousands of hours of original field observations, research in the literature, a wealth of illustrations, and—in the e-book edition and online—video segments from cinematographer Robert K. Landis, the authors create a compelling and complex picture of these hunters. The wolf is indeed an adept killer, able to take down prey much larger than itself. While adapted to hunt primarily hoofed animals, a wolf—or especially a pack of wolves—can kill individuals of just about any species. But even as wolves help drive the underlying rhythms of the ecosystems they inhabit, their evolutionary prowess comes at a cost: wolves spend one-third of their time hunting—the most time consuming of all wolf activities—and success at the hunt only comes through traveling long distances, persisting in the face of regular failure, detecting and taking advantage of deficiencies in the physical condition of individual prey, and through ceaseless trial and error, all while risking injury or death. By describing and analyzing the behaviors wolves use to hunt and kill various wild prey—including deer, moose, caribou, elk, Dall sheep, mountain goats, bison, musk oxen, arctic hares, beavers, and others—Wolves on the Hunt provides a revelatory portrait of one of nature’s greatest hunters.

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

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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

Plastic debris in great skua (Stercorarius skua) pellets corresponds to seabird prey species.

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Hammer, S; Nager, R G; Johnson, P C D; Furness, R W; Provencher, J F

2016-02-15

Plastic is a common item in marine environments. Studies assessing seabird ingestion of plastics have focused on species that ingest plastics mistaken for prey items. Few studies have examined a scavenger and predatory species that are likely to ingest plastics indirectly through their prey items, such as the great skua (Stercorarius skua). We examined 1034 regurgitated pellets from a great skua colony in the Faroe Islands for plastics and found approximately 6% contained plastics. Pellets containing remains of Northern fulmars (Fulmarus glacialis) had the highest prevalence of plastic. Our findings support previous work showing that Northern fulmars have higher loads of plastics than other sympatric species. This study demonstrates that marine plastic debris is transferred from surface feeding seabird species to predatory great skuas. Examination of plastic ingestion in species that do not ingest plastics directly can provide insights into how plastic particles transfer vertically within the food web. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pathogens, nutritional deficiency, and climate influences on a declining moose population

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Murray, D.L.; Cox, E.W.; Ballard, W.B.; Whitlaw, Heather A.; Lenarz, M.S.; Custer, T.W.; Barnett, T.; Fuller, T.K.

2006-01-01

Several potential proximate causes may be implicated in a recent (post-1984) decline in moose (Alces alces andersoni) numbers at their southern range periphery in northwest Minnesota, USA. These causes include deleterious effects of infectious pathogens, some of which are associated with white-tailed deer (Odocoileus virginianus), negative effects of climate change, increased food competition with deer or moose, legal or illegal hunting, and increased predation by gray wolves (Canis lupus) and black bears (Ursus americanus). Long-standing factors that may have contributed to the moose decline include those typically associated with marginal habitat such as nutritional deficiencies. We examined survival and productivity among radiocollared (n = 152) adult female and juvenile moose in northwest Minnesota during 1995–2000, and assessed cause of death and pathology through carcass necropsy of radiocollared and non-radiocollared animals.Aerial moose surveys suggested that hunting was an unlikely source of the numerical decline because the level of harvest was relatively low (i.e., approx. 15% / 2 yr) and the population usually grew in years following a hunt. The majority of moose mortalities (up to 87% of radiocollared moose [n = 76] and up to 65% of non-radiocollared moose [n = 84]) were proximally related to pathology associated with parasites and infectious disease. Liver fluke (Fascioloides magna) infections apparently constituted the greatest single source of mortality and caused significant pathology in the liver, thoracic and peritoneal cavities, pericardial sac, and lungs. Mortality due to meningeal worm (Parelaphostrongylus tenuis) was less prevalent and was manifested through characteristic neurological disease. Several mortalities apparently were associated with unidentified infectious disease, probably acting in close association with malnutrition. Bone-marrow fat was lower for moose dying of natural causes than those dying of anthropogenic factors or

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

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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.

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

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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.

The Nutritional Balancing Act of a Large Herbivore: An Experiment with Captive Moose (Alces alces L).

Science.gov (United States)

Felton, Annika M; Felton, Adam; Raubenheimer, David; Simpson, Stephen J; Krizsan, Sophie J; Hedwall, Per-Ola; Stolter, Caroline

2016-01-01

The nutrient balancing hypothesis proposes that, when sufficient food is available, the primary goal of animal diet selection is to obtain a nutritionally balanced diet. This hypothesis can be tested using the Geometric Framework for nutrition (GF). The GF enables researchers to study patterns of nutrient intake (e.g. macronutrients; protein, carbohydrates, fat), interactions between the different nutrients, and how an animal resolves the potential conflict between over-eating one or more nutrients and under-eating others during periods of dietary imbalance. Using the moose (Alces alces L.), a model species in the development of herbivore foraging theory, we conducted a feeding experiment guided by the GF, combining continuous observations of six captive moose with analysis of the macronutritional composition of foods. We identified the moose's self-selected macronutrient target by allowing them to compose a diet by mixing two nutritionally complementary pellet types plus limited access to Salix browse. Such periods of free choice were intermixed with periods when they were restricted to one of the two pellet types plus Salix browse. Our observations of food intake by moose given free choice lend support to the nutrient balancing hypothesis, as the moose combined the foods in specific proportions that provided a particular ratio and amount of macronutrients. When restricted to either of two diets comprising a single pellet type, the moose i) maintained a relatively stable intake of non-protein energy while allowing protein intakes to vary with food composition, and ii) increased their intake of the food item that most closely resembled the self-selected macronutrient intake from the free choice periods, namely Salix browse. We place our results in the context of the nutritional strategy of the moose, ruminant physiology and the categorization of food quality.

The Nutritional Balancing Act of a Large Herbivore: An Experiment with Captive Moose (Alces alces L.

Directory of Open Access Journals (Sweden)

Annika M Felton

Full Text Available The nutrient balancing hypothesis proposes that, when sufficient food is available, the primary goal of animal diet selection is to obtain a nutritionally balanced diet. This hypothesis can be tested using the Geometric Framework for nutrition (GF. The GF enables researchers to study patterns of nutrient intake (e.g. macronutrients; protein, carbohydrates, fat, interactions between the different nutrients, and how an animal resolves the potential conflict between over-eating one or more nutrients and under-eating others during periods of dietary imbalance. Using the moose (Alces alces L., a model species in the development of herbivore foraging theory, we conducted a feeding experiment guided by the GF, combining continuous observations of six captive moose with analysis of the macronutritional composition of foods. We identified the moose's self-selected macronutrient target by allowing them to compose a diet by mixing two nutritionally complementary pellet types plus limited access to Salix browse. Such periods of free choice were intermixed with periods when they were restricted to one of the two pellet types plus Salix browse. Our observations of food intake by moose given free choice lend support to the nutrient balancing hypothesis, as the moose combined the foods in specific proportions that provided a particular ratio and amount of macronutrients. When restricted to either of two diets comprising a single pellet type, the moose i maintained a relatively stable intake of non-protein energy while allowing protein intakes to vary with food composition, and ii increased their intake of the food item that most closely resembled the self-selected macronutrient intake from the free choice periods, namely Salix browse. We place our results in the context of the nutritional strategy of the moose, ruminant physiology and the categorization of food quality.

Long term behavior of radiocaesium in moose: conclusions from 25 years of monitoring

Energy Technology Data Exchange (ETDEWEB)

Weimer, R.; Sonesten, L.; Goedkoop, W. [Department of Aquatic Sciences and Assessment (Sweden); Sundell-Bergman, S.; Rosen, K. [Department of Soil and Environment (Sweden); Wikenros, C. [Department of Ecology (Sweden)

2014-07-01

Radiocesium ({sup 137}Cs) deposited after the Chernobyl nuclear disaster in 1986, still persist in forest ecosystems in parts of Sweden at relatively high concentrations. In the forest, radiocaesium is assumed to be reversibly bound to the soil, which facilitates its uptake by plant roots and fungal mycelia thus making it available, as fodder, to wild animals. Even today this leads to contaminated meat from moose (Alces alces) and other game species. Around 100 000 moose, approximately 1/3 of the whole population, are shot each year in Sweden which makes moose the main source of consumed game meat. Hence understanding the long-term behavior of radiocaesium in forest ecosystems is important for the evaluation of future potential health risks to consumers. The two municipalities of Heby and Uppsala, in east-central Sweden, experienced relatively large deposition in 1986 (5 - 100 kBq/m{sup 2}). Monitoring of the {sup 137}Cs activity concentrations in meat from moose hunted in these areas was initiated already in autumn 1986 and is still continuing. Muscle samples from front leg of the slaughtered moose are received from local hunters during the hunting season and more than 3500 samples have been collected during the years. The samples are adjoined with a sampling protocol containing information on estimated age, sex and weight, as well as where and when each moose was shot. Gamma spectrometry of the {sup 137}Cs- activities is performed on fresh or frozen moose muscle samples using HPGe detectors. The main part of all the samples analyzed since 1986 are from the northern part of Heby municipality. This study area covers approximately 400 km{sup 2} and received a mean ground deposition of approximately 35 kBq/m{sup 2} of {sup 137}Cs in 1986. The area is dominated by managed coniferous forests, but also includes large parts of agricultural land. A database of > 3 500 moose samples collected from hunts between 1986 and 2010 was used in this study. The results of the

NEAMS-IPL MOOSE Midyear Framework Activities

International Nuclear Information System (INIS)

Permann, Cody; Alger, Brian; Peterson, John; Slaughter, Andrew; Andrš, David; Martineau, Richard

2017-01-01

The MOOSE Framework is a modular pluggable framework for building complex simulations. The ability to add new objects with custom syntax is a core capability that makes MOOSE a powerful platform for coupling multiple applications together within a single environment. The creation of a new, more standardized JSON syntax output improves the external interfaces for generating graphical components or for validating input file syntax. The design of this interface and the requirements it satisfies are covered in this short report.

NEAMS-IPL MOOSE Midyear Framework Activities

Energy Technology Data Exchange (ETDEWEB)

Permann, Cody [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alger, Brian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Peterson, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); Slaughter, Andrew [Idaho National Lab. (INL), Idaho Falls, ID (United States); Andrš, David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Martineau, Richard [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2017-05-09

The MOOSE Framework is a modular pluggable framework for building complex simulations. The ability to add new objects with custom syntax is a core capability that makes MOOSE a powerful platform for coupling multiple applications together within a single environment. The creation of a new, more standardized JSON syntax output improves the external interfaces for generating graphical components or for validating input file syntax. The design of this interface and the requirements it satisfies are covered in this short report.

The “Destabilizing” Effect of Cannibalism in a Spatially Explicit Three-Species Age Structured Predator-Prey Model

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Aladeen Al Basheer

2017-01-01

Full Text Available Cannibalism, the act of killing and consumption of conspecifics, is generally considered to be a stabilising process in ODE models of predator-prey systems. On the other hand, Sun et al. were the first to show that cannibalism can cause Turing instability, in the classical Rosenzweig-McArthur two-species PDE model, which is an impossibility without cannibalism. Magnússon’s classic work is the first to show that cannibalism in a structured three-species predator-prey ODE model can actually be destabilising. In the current manuscript we consider the PDE form of the three-species model proposed in Magnússon’s classic work. We prove that, in the absence of cannibalism, Turing instability is an impossibility in this model, for any range of parameters. However, the inclusion of cannibalism can cause Turing instability. Thus, to the best of our knowledge, we report the first cannibalism induced Turing instability result, in spatially explicit three-species age structured predator-prey systems. We also show that, in the classical ODE model proposed by Magnússon, cannibalism can act as a life boat mechanism, for the prey.

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

High prevalence of hepatitis e virus in Swedish moose--a phylogenetic characterization and comparison of the virus from different regions.

Directory of Open Access Journals (Sweden)

Jay Lin

Full Text Available Hepatitis E virus (HEV infects a range of species, including humans, pigs, wild boars and deer. Zoonotic transmission may contribute to the high HEV seroprevalence in the human population of many countries. A novel divergent HEV from moose (Alces alces in Sweden was recently identified by partial genome sequencing. Since only one strain was found, its classification within the HEV family, prevalence in moose and zoonotic potential was unclear. We therefore investigated samples from 231 moose in seven Swedish counties for HEV, and sequenced a near complete moose HEV genome. Phylogenetic analysis to classify this virus within the family Hepeviridae and to explore potential host specific determinants was performed.The HEV prevalence of moose was determined by PCR (marker for active infection and serological assays (marker of past infection of sera and 51 fecal samples from 231 Swedish moose. Markers of active and past infection were found in 67 (29% animals, while 34 (15% were positive for HEV RNA, 43 (19% were seropositive for anti-HEV antibodies, and 10 (4% had both markers. The number of young individuals positive for HEV RNA was larger than for older individuals, and the number of anti-HEV antibody positive individuals increased with age. The high throughput sequenced moose HEV genome was 35-60% identical to existing HEVs. Partial ORF1 sequences from 13 moose strains showed high similarity among them, forming a distinct monophyletic clade with a common ancestor to HEV genotype 1-6 group, which includes members known for zoonotic transmission.This study demonstrates a high frequency of HEV in moose in Sweden, with markers of current and past infection demonstrated in 30% of the animals. Moose is thus an important animal reservoir of HEV. The phylogenetic relationship demonstrated that the moose HEV belonged to the genotype 1-6 group, which includes strains that also infect humans, and therefore may signify a potential for zoonotic transmission

Activity concentrations of [sup 137]Cs in moose and their forage plants in mid-Sweden

Energy Technology Data Exchange (ETDEWEB)

Johanson, K.J. (Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Radioecology); Bergstroem, Roger (Swedish Hunters' Association, Uppsala (Sweden). Research Unit); Eriksson, Olof (Uppsala Univ. (Sweden). Dept. of Ecological Botany); Erixon, Allan (Hunters' Association of Vaesternorrland, Haernoesand (Sweden))

1994-01-01

The [sup 137]s activity concentrations in moose and their principal fodder plants as well as the botanical composition of the rumen content in moose were studied in three areas of the county of Vaesternorrland in Sweden. The mean [sup 137]Cs activity concentration in moose muscle samples from the three areas with a ground deposition from 20 to 60 kBq m[sup -2] varied between 540 and 915 Bq kg[sup -1]. During the period July to October, three plant species - fireweed, birch and bilberry - constitute more than 70% of the rumen content. Estimation of the daily [sup 137]Cs intake was performed based on the botanical analysis of rumen content and the [sup 137]Cs activity concentrations found in samples of fodder plants. A mean F[sub f] of 0.19 day kg[sup -1] was calculated. A mean aggregated transfer factor of 0.016 m[sup 2] kg[sup -1] was found for the three areas. (author).

Transfer parameters in the water/forage/moose pathway

International Nuclear Information System (INIS)

1987-07-01

Moose tissue samples and associated water and drinking water samples were collected from the Serpent River Drainage Area (Study Area) and outside of the watershed (Controls) during the fall of 1985. The concentrations of lead-210, polonium-210, radium-226, thorium and uranium were determined for both the study area and control samples. The radionuclide radium-226 was evaluated in the drinking water, vegetation and moose tissue to determine concentration factors. No statistical difference was found between study and control samples. Concentration factors from vegetation to moose tissue were found to range from 0.036 to 3.03 depending upon tissue type. Radionuclide concentrations found in this study were shown to be within known background levels. 2 maps

Predation as a landscape effect: the trading off by prey species between predation risks and protection benefits.

Science.gov (United States)

Mönkkönen, M; Husby, M; Tornberg, R; Helle, P; Thomson, R L

2007-05-01

1. Predators impose costs on their prey but may also provide benefits such as protection against other (e.g. nest) predators. The optimal breeding location in relation to the distance from a nesting raptor varies so as to minimize the sum of costs of adult and nest predation. We provide a conceptual model to account for variation in the relative predation risks and derive qualitative predictions for how different prey species should respond to the distance from goshawk Accipiter gentilis nests. 2. We test the model predictions using a comprehensive collection of data from northern Finland and central Norway. First, we carried out a series of experiments with artificial bird nests to test if goshawks may provide protection against nest predation. Second, we conducted standard bird censuses and nest-box experiments to detect how the density or territory occupancy of several prey species varies with distance from the nearest goshawk nest. 3. Nest predation rate increased with distance from goshawk nest indicating that goshawks may provide protection for birds' nests against nest predation. Abundance (or probability of presence) of the main prey species of goshawks peaked at intermediate distances from goshawk nests, reflecting the trade-off. The abundance of small songbird species decreased with distance from goshawk nests. The goshawk poses little risk to small songbirds and they may benefit from goshawk proximity in protection against nest predation. Finally, no pattern with distance in pied flycatcher territory (nest box) occupation rate or the onset of egg-laying was detected. This is expected, as flycatchers neither suffer from marked nest predation risk nor are favoured goshawk prey. 4. Our results suggest that territory location in relation to the nest of a predator is a trade-off situation where adult birds weigh the risk of themselves being predated against the benefits accrued from increased nest survival. Prey species appear able to detect and measure

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.

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.

Bull Moose Tube Company

Science.gov (United States)

The EPA is providing notice of a proposed Administrative Penalty Assessment against the Bull Moose Tube Company, a business located at 1819 Clarkson Road, Chesterfield, MO, 63017, for alleged violations at the facility located at 406 East Industrial Drive,

An historical overview and update of wolf-moose interactions in northeastern Minnesota

Science.gov (United States)

Mech, L. David; Fieberg, John; Barber-Meyer, Shannon

2018-01-01

Wolf (Canis lupus) and moose (Alces americanus) populations in northeastern Minnesota, USA, have fluctuated for decades and, based on helicopter counts, moose numbers declined to a new low from 2006 to about 2012. Other steep declines were found in 1991 and 1998 during periods when moose counts were done with ®xed-wing aircraft; these declines also appeared to be real. Winter wolf numbers, monitored in part of the moose range, had been increasing since about 2002 to the highest population in decades in 2009. However, from 2009 to 2016, wolves decreased precipitously, and the moose-population decline leveled off from 2012 to 2017. Calf:population ratios from 1985 to 1997 and from 2005 to 2016 were inversely related to wolf numbers in the wolf-study area the previous winter both as wolves increased and decreased in abundance. Similarly, log annual growth rates of moose numbers were negatively correlated with counts of wolves in the prior year. Other factors such as nutrition and parasites, and possibly climate change, likely have been involved in the recent moose decline. However, wolves, as in other areas, appear to have contributed to the decline in the northeastern Minnesota moose population at least in part through predation on calves, supporting earlier reports. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

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....

Diet shift of a facultative scavenger, the wolverine, following recolonization of wolves.

Science.gov (United States)

van Dijk, Jiska; Gustavsen, Line; Mysterud, Atle; May, Roel; Flagstad, Øystein; Brøseth, Henrik; Andersen, Roy; Andersen, Reidar; Steen, Harald; Landa, Arild

2008-11-01

1. Wolves Canis lupus L. recolonized the boreal forests in the southern part of the Scandinavian peninsula during the late 1990s, but so far there has been little attention to its effect on ecosystem functioning. Wolf predation increases the availability of carcasses of large prey, especially moose Alces alces L., which may lead in turn to a diet switch in facultative scavengers such as the wolverine Gulo gulo L. 2. Using 459 wolverine scats collected during winter-spring 2001-04 for DNA identity and dietary contents, we compared diet inside and outside wolf territories while controlling for potential confounding factors, such as prey density. We tested the hypothesis that wolverine diet shifted towards moose in the presence of wolves, while taking into account possible sexual segregation between the sexes. Occurrence of reindeer, moose and small prey was modelled against explanatory covariates using logistic mixed-effects models. Furthermore, we compared diet composition and breadth among habitats and sexes. 3. Occurrence of reindeer, moose and small prey in the diet varied with prey availability and habitat. As expected, diet contained more moose and less reindeer and small prey in the presence of wolves. Their diet in tundra consisted of 40% reindeer Rangifer tarandus L., 39% moose and 9% rodents. In forest with wolf, their diet shifted to 76% moose, 18% reindeer and 5% rodents; compared to 42% moose, 32% reindeer and 15% rodents in forest without wolf. This diet switch could not be explained by higher moose density in wolf territories. Female diet consisted of more small prey than for males, but there was a tendency for females to use the highly available moose carrion opportunistically and to hunt less on small prey within wolf territories. 4. Our study highlights how wolves increase scavenging opportunities for wolverines, and how sexual differences in diet may also apply to large scavengers. Due to their more restricted home range, female wolverines are

Radiocaesium transfer to man from moose and roe deer in Sweden

International Nuclear Information System (INIS)

Johanson, Karl J.; Bergstroem, R.

1994-01-01

Studies of radiocaesium in the forest ecosystems in Sweden resulted in aggregated transfer factors quantified for the transfer of 137 Cs from soil to moose and roe deer. These aggregated transfer factors were 0.02 m 2 kg -1 for moose and 0.05 m 2 kg -1 for roe deer. There seems to be no decrease in the 137 Cs activity concentrations in moose harvested in our research area and therefore we suggest the use of the physical half-life of 137 Cs (30 years) as the effective ecological half-life. The time-integrated transfer of 137 Cs from the Chernobyl fall-out to man by moose in Sweden was calculated and found to be 115 GBq, corresponding to 1500 man Sv for moose. The time-integrated transfer by roe deer to man was estimated to be between 25-48 GBq, corresponding to 327-620 man Sv for roe deer. The annual transfer of 137 Cs to man by moose has varied between 2.0-2.7 GBq, corresponding to 27-34 man Sv. Depending on the group studied, the mean annual transfer of 137 Cs can be calculated to be from about 250 to 43'000 Bq. For example, the mean annual transfer of 137 Cs by moose to hunters and their families in Gaevle commune, the most affected commune in Sweden, was estimated to be about 26'000 Bq, corresponding to 0.34 mSv

Metabolic rate of spiders (Pardosa prativage) feed on prey species of different diet quality measured by colorimetry

DEFF Research Database (Denmark)

Nielsen, Søren Achim; Kynde, Bjarke; Westh, Peter

The metabolic rate was measured in the wolf spider Pardosa prativaga after preying different species of aphids, collembolans and fruit flies raised on common commercial medium. The activity of detoxification enzyme systems Glutathione S-Transferase (GST), Glutathione Peroxidase (GSTpx) was invest......The metabolic rate was measured in the wolf spider Pardosa prativaga after preying different species of aphids, collembolans and fruit flies raised on common commercial medium. The activity of detoxification enzyme systems Glutathione S-Transferase (GST), Glutathione Peroxidase (GSTpx......) was investigated for spiders preying the different species. The heat production of starved P. prativaga was ca. 1.5 mW per mg fresh weight. For specimens feed on fruit flies (Drosophila melanogaster) the heat production was appreciable higher whereas feed on the aphids Sitobion avenae and Rhopalosiphum padi...... the heat production was on the same level or lower than in the staved spiders. The variation of the observed metabolic changes was in concordance with the variations in enzyme activities....

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.

Polycyclic aromatic hydrocarbons in caribou, moose, and wolf scat samples from three areas of the Alberta oil sands

International Nuclear Information System (INIS)

Lundin, Jessica I.; Riffell, Jeffrey A.; Wasser, Samuel K.

2015-01-01

Impacts of toxic substances from oil production in the Alberta oil sands (AOS), such as polycyclic aromatic hydrocarbons (PAHs), have been widely debated. Studies have been largely restricted to exposures from surface mining in aquatic species. We measured PAHs in Woodland caribou (Rangifer tarandus caribou), moose (Alces americanus), and Grey wolf (Canis lupus) across three areas that varied in magnitude of in situ oil production. Our results suggest a distinction of PAH level and source profile (petro/pyrogenic) between study areas and species. Caribou samples indicated pyrogenic sourced PAHs in the study area previously devastated by forest fire. Moose and wolf samples from the high oil production area demonstrated PAH ratios indicative of a petrogenic source and increased PAHs, respectively. These findings emphasize the importance of broadening monitoring and research programs in the AOS. - Highlights: • We measured PAHs from areas with varying degrees of in situ oil production activity. • PAH levels were measured in scat samples from three terrestrial species. • Caribou indicated pyrogenic PAHs in the area previously devastated by forest fire. • High oil production area moose and wolf showed petrogenic PAH characteristics. • Further scientific investigation of PAH exposures in these areas is warranted. - We demonstrate a distinction of PAH level and source profile in scat samples of three large mammals collected from areas with varying degrees of in situ oil production.

Chernobyl cesium in the Swedish moose population: Effect of age, diet and habitat selection

International Nuclear Information System (INIS)

Nelin, P.

1994-01-01

The most important game in Sweden is moose (Alces alces (L.)). To study the 137 Cs levels in moose, hunters were asked to send in moose meat for analysis. About 6500 samples were analysed from 1986-1993. There was a positive correlation between the fall-out of cesium from Chernobyl and the cesium concentration in moose. The differences in 137 Cs concentration between moose of the same age and sex, results from individual moose consuming plants of different 137 Cs concentrations, due to the use of different habitat types. The differences in 137 Cs levels between years probably depends on between-year variation in habitat utilization due to the weather. During warm summers and autumns, moose utilize more wetlands (cool habitats during warm days) or mature forests (which are shady during sunny days) and consume the plants (of high 137 Cs levels) found there, whereby their meat will have a higher 137 Cs concentration. If, during colder summers, moose instead use farmlands or clear-cut forest areas and consume the plants (of low 137 Cs levels) found there, a lower 137 Cs concentration will be the case. The 137 Cs concentration in moose also fluctuates seasonally depending on diet, i.e. there are high average concentrations and large differences between individual moose killed during the plant growing season, but low 137 Cs concentrations and low variation between individuals and years, for moose killed during the winter. The analyses of 137 Cs in moose and its food plants from before and after the Chernobyl accident indicates that the 137 Cs from Chernobyl will stay in the northern forest ecosystem for a long time. The physical decay (30.2 years) seems to be the major factor for its disappearance from the ecosystem. I also expect that the fluctuation between years in the 137 Cs concentration will persist, although decrease in maximum values. 44 refs, 7 figs

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.

Prey species as possible sources of PBDE exposures for peregrine falcons (Falco peregrinus) nesting in major California cities.

Science.gov (United States)

Park, June-Soo; Fong, Alison; Chu, Vivian; Holden, Arthur; Linthicum, Janet; Hooper, Kim

2011-04-01

Our earlier findings indicate that (1) peregrine falcons (Falco peregrinus anatum Bonaparte) nesting in major California cities have among the highest polybrominated diphenyl ether (PBDE) levels in the world (max ∑PBDEs=100 ppm), and (2) Big City peregrines have higher levels and proportions of the higher-brominated congeners (hepta- to deca-BDEs) than do their Coastal counterparts. In this study we classified the prey species (n =185) from the remains of prey (feathers) at 38 peregrine nest sites over 25 years (1974-1998). We grouped the prey species into 15 categories based on diet and found distinctly different prey patterns for Big City vs. Coastal peregrines. Big City peregrines had a higher (almost three times) weight percentage intake of food waste-eating birds (e.g., rock pigeons, Columba livia) than Coastal peregrines. These differing prey patterns suggest diet as a potential source of the unusually high levels and proportions of higher-brominated PBDEs in Big City peregrines. The relative contributions of diet and dust (e.g., preening) exposure to PBDE patterns in Big City peregrines will be explored in future investigations. © Springer Science+Business Media, LLC 2010

Plasma lactate concentrations in free-ranging moose (Alces alces) immobilized with etorphine.

Science.gov (United States)

Haga, Henning A; Wenger, Sandra; Hvarnes, Silje; Os, Oystein; Rolandsen, Christer M; Solberg, Erling J

2009-11-01

To investigate plasma lactate concentrations of etorphine-immobilized moose in relation to environmental, temporal and physiological parameters. Prospective clinical study. Fourteen female and five male moose (Alces alces), estimated age range 1-7 years. The moose were darted from a helicopter with 7.5 mg etorphine per animal using projectile syringes and a dart gun. Once immobilized, the moose were approached, a venous blood sample was obtained and vital signs including pulse oximetry were recorded. Diprenorphine was administered to reverse the effects of etorphine. Timing of events, ambient temperature and snow depth were recorded. Blood samples were cooled and centrifuged before plasma was harvested and frozen. The plasma was thawed later and lactate analysed. Data were analysed using descriptive statistics and regression analysis. All animals recovered uneventfully and were alive 12 weeks after immobilization. Mean +/- SD plasma lactate was found to be 9.2 +/- 2.1 mmol L(-1). Plasma lactate concentrations were related positively to snow depth and negatively to time from induction of immobilization to blood sampling. The model that best described the variability in plasma lactate concentrations used induction time (time from firing the dart to the moose being immobilized). The second best model included induction time and snow depth. Plasma lactate concentrations in these etorphine-immobilized moose were in the range reported for other immobilized wild ruminants. Decreasing induction time, which may be related to a more profound etorphine effect, and increasing snow depth possibly may increase plasma lactate concentrations in etorphine-immobilized moose.

NEAMS-IPL MOOSE Framework Activities

Energy Technology Data Exchange (ETDEWEB)

Slaughter, Andrew Edward [Idaho National Lab. (INL), Idaho Falls, ID (United States); Permann, Cody James [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kong, Fande [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-09-01

The Multiapp Picard iteration Milestone’s purpose was to support a framework level “tight-coupling” method within the hierarchical Multiapp’s execution scheme. This new solution scheme gives developers new choices for running multiphysics applications, particularly those with very strong nonlinear effects or those requiring coupling across disparate time or spatial scales. Figure 1 shows a typical Multiapp setup in MOOSE. Each node represents a separate simulation containing a separate equation system. MOOSE solves the equation system on each node in turn, in a user-controlled manner. Information can be aggregated or split and transferred from parent to child or child to parent as needed between solves. Performing a tightly coupled execution scheme using this method wasn’t possible in the original implementation. This is was due to the inability to back up to a previous state once a converged solution was accepted at a particular Multiapp level.

NEAMS-IPL MOOSE Framework Activities

International Nuclear Information System (INIS)

Slaughter, Andrew Edward; Permann, Cody James; Kong, Fande

2016-01-01

The Multiapp Picard iteration Milestone's purpose was to support a framework level ''tight-coupling'' method within the hierarchical Multiapp's execution scheme. This new solution scheme gives developers new choices for running multiphysics applications, particularly those with very strong nonlinear effects or those requiring coupling across disparate time or spatial scales. Figure 1 shows a typical Multiapp setup in MOOSE. Each node represents a separate simulation containing a separate equation system. MOOSE solves the equation system on each node in turn, in a user-controlled manner. Information can be aggregated or split and transferred from parent to child or child to parent as needed between solves. Performing a tightly coupled execution scheme using this method wasn't possible in the original implementation. This is was due to the inability to back up to a previous state once a converged solution was accepted at a particular Multiapp level.

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.

The effects of prey size on diet differentiation of seven passerine species at two spring stopover sites

NARCIS (Netherlands)

Marchetti, C.M.; Locatelli, D.P.; Van Noordwijk, A.J.; Baldaccini, N.E.

1998-01-01

Prey size was evaluated for seven passerine trans-Saharan migrant species at two spring stopover sites in Sardinia, Italy. The species considered were Pied Flycatcher Ficedula hypoleuca, Spotted Flycatcher Muscicapa striata, Redstart Phoenicurus phoenicurus, Garden Warbler Sylvia borin, Whitethroat

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.

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.

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

Dash Cam videos on YouTube™ offer insights into factors related to moose-vehicle collisions.

Science.gov (United States)

Rea, Roy V; Johnson, Chris J; Aitken, Daniel A; Child, Kenneth N; Hesse, Gayle

2018-03-26

To gain a better understanding of the dynamics of moose-vehicle collisions, we analyzed 96 videos of moose-vehicle interactions recorded by vehicle dash-mounted cameras (Dash Cams) that had been posted to the video-sharing website YouTube™. Our objective was to determine the effects of road conditions, season and weather, moose behavior, and driver response to actual collisions compared to near misses when the collision was avoided. We identified 11 variables that were consistently observable in each video and that we hypothesized would help to explain a collision or near miss. The most parsimonious logistic regression model contained variables for number of moose, sight time, vehicle slows, and vehicle swerves (AIC c w = 0.529). This model had good predictive accuracy (AUC = 0.860, SE = 0.041). The only statistically significant variable from this model that explained the difference between moose-vehicle collisions and near misses was 'Vehicle slows'. Our results provide no evidence that road surface conditions (dry, wet, ice or snow), roadside habitat type (forested or cleared), the extent to which roadside vegetation was cleared, natural light conditions (overcast, clear, twilight, dark), season (winter, spring and summer, fall), the presence of oncoming traffic, or the direction from which the moose entered the roadway had any influence on whether a motorist collided with a moose. Dash Cam videos posted to YouTube™ provide a unique source of data for road safety planners trying to understand what happens in the moments just before a moose-vehicle collision and how those factors may differ from moose-vehicle encounters that do not result in a collision. Copyright © 2018 Elsevier Ltd. All rights reserved.

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.

Growth and grazing responses of two chloroplast-retaining dinoflagellates: effect of irradiance and prey species

DEFF Research Database (Denmark)

Jakobsen, Hans Henrik; Hansen, P.J.; Larsen, J.

2000-01-01

The effect of irradiance on growth and grazing responses of 2 phagotrophic dinoflagellates, Gymnodinium gracilentum Campbell 1973 and Amphidinium poecilochroum Larsen 1985, was studied. While G. gracilentum belongs to the plankton, A. poecilochroum is a benthic species that primarily feeds on prey...

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

Hematology and serum chemistry reference ranges of free-ranging moose (Alces Alces) in Norway

OpenAIRE

Rostal, Melinda K.; Evans, Alina L.; Solberg, Erling L.; Arnemo, Jon Martin

2012-01-01

This article is also available here: http://www.jwildlifedis.org/ Baseline reference ranges of serum chemistry and hematology data can be important indicators for the status of both individuals or populations of wild animals that are affected by emerging pathogens, toxicants, or other causes of disease. Frequently, reference ranges for these values are not available for wildlife species or subspecies. We present hematologic and serum chemistry reference ranges for moose (Alces ...

MOOSE: A parallel computational framework for coupled systems of nonlinear equations

International Nuclear Information System (INIS)

Gaston, Derek; Newman, Chris; Hansen, Glen; Lebrun-Grandie, Damien

2009-01-01

Systems of coupled, nonlinear partial differential equations (PDEs) often arise in simulation of nuclear processes. MOOSE: Multiphysics Object Oriented Simulation Environment, a parallel computational framework targeted at the solution of such systems, is presented. As opposed to traditional data-flow oriented computational frameworks, MOOSE is instead founded on the mathematical principle of Jacobian-free Newton-Krylov (JFNK). Utilizing the mathematical structure present in JFNK, physics expressions are modularized into 'Kernels,' allowing for rapid production of new simulation tools. In addition, systems are solved implicitly and fully coupled, employing physics-based preconditioning, which provides great flexibility even with large variance in time scales. A summary of the mathematics, an overview of the structure of MOOSE, and several representative solutions from applications built on the framework are presented.

Observations on the Nesting and Prey of the Solitary Wasp, Tachysphex inconspicuus, with a Review of Nesting Behavior in the T. obscuripennis species group

Science.gov (United States)

Kurczewski, Frank E.; Coville, Rollin E.; Schal, Coby

2010-01-01

The nesting behaviors of 10 females of Tachysphex inconspicuus (Kirby) (Hymenoptera: Crabronidae) were studied on a sandy, mowed lawn at the La Selva Biological Station in northeastern Costa Rica on 27–29 April 1980. Twenty-four completed nests were observed, excavated, and measured. The nests had oblique, short burrows leading to one or two shallow cells. Prey cockroaches belonging to 11 species of Chorisoneura and Riatia fulgida (Saussure) (Blattaria: Blattellidae), all tropical wet forest canopy indicator species, were removed from the cells, weighed, and identified. The cockroaches consisted mainly of adult females, selectively preyed upon over adult males and nymphs due to their larger sizes. The aggregate prey mass in cells was separable into prospective larger (heavier) female and smaller (lighter) male cells. Wasps usually oviposited on the heaviest cockroach in a cell, in most cases an adult female. Atypical genus behavior included (1) prey being carried to one side of the wasp and perhaps grasped by a hindleg during removal of the temporary entrance closure and nest entry and (2) wasp's egg being laid affixed to a forecoxal corium and extending backward in a longitudinally posteriad position across the prey's ventral thorax. A comparison with the nesting behavior of other species in the Tachysphex obscuripennis species group is made. PMID:21062142

The transfer of fallout cesium-137 from browse to moose. Part 1

International Nuclear Information System (INIS)

Zach, R.; Mayoh, K.R.

1982-09-01

We are investigating the transfer of fallout cesium-137 from soil to browse to moose (Alces alces) to wolf (Canis lupis) to promote our understanding of the movement of radionuclides through natural food chains. The first part of this study is concerned with moose food habits. Early winter food habits of moose from Hecla Island and Manitoba Game Hunting Area 26 in south central and south eastern Manitoba were studied. In 86 rumen samples, 25 food types were identified. Three methods of food habit determination were used: (1) percentage occurrence of food types, (2) subjective abundance scores and (3) percentage dry weight. All three methods yielded very similar results

Assessing the Utility of Temporally Dynamic Terrain Indices in Alaskan Moose Resource Selection

Science.gov (United States)

Jennewein, J. S.; Hebblewhite, M.; Meddens, A. J.; Gilbert, S.; Vierling, L. A.; Boelman, N.; Eitel, J.

2017-12-01

The accelerated warming in arctic and boreal regions impacts ecosystem structure and plant species distribution, which have secondary effects on wildlife. In summer months, moose (Alces alces) are especially vulnerable to changes in the availability and quality of forage and foliage cover due to their thermoregulatory needs and high energetic demands post calving. Resource selection functions (RSFs) have been used with great success to model such tradeoffs in habitat selection. Recently, RSFs have expanded to include more dynamic representations of habitat selection through the use of time-varying covariates such as dynamic habitat indices. However, to date few studies have investigated dynamic terrain indices, which incorporate long-term, highly-dynamic meteorological data (e.g., albedo, air temperature) and their utility in modeling habitat selection. The purpose of this study is to compare two dynamic terrain indices (i.e., solar insolation and topographic wetness) to their static counterparts in Alaskan moose resource selection over a ten-year period (2008-2017). Additionally, the utility of a dynamic wind-shelter index is assessed. Three moose datasets (n=130 total), spanning a north-to-south gradient in Alaska, are analyzed independently to assess location-specific resource selection. The newly-released, high-resolution Arctic Digital Elevation Model (5m2) is used as the terrain input into both dynamic and static indices. Dynamic indices are programmed with meteorological data from the North American Regional Analysis (NARR) and NASA's Goddard Earth Sciences Data and Information Services Center (GES-DISC) databases. Static wetness and solar insolation indices are estimated using only topographic parameters (e.g., slope, aspect). Preliminary results from pilot analyses suggest that dynamic terrain indices may provide novel insights into resource selection of moose that could not be gained when using static counterparts. Future applications of such dynamic

Reducing Moose-Vehicle Collisions through Salt Pool Removal and Displacement: an Agent-Based Modeling Approach

Directory of Open Access Journals (Sweden)

Paul D. Grosman

2009-12-01

Full Text Available Between 1990 and 2002, more than 200 moose-vehicle collisions occurred each year in Quebec, including about 50/yr in the Laurentides Wildlife Reserve. One cause is the presence of roadside salt pools that attract moose near roads in the spring and summer. Using the computer simulation technique of agent-based modeling, this study investigated whether salt pool removal and displacement, i.e., a compensatory salt pool set up 100 to 1500 m away from the road shoulder, would reduce the number of moose-vehicle collisions. Moose road crossings were used as a proxy measure. A GPS telemetry data set consisting of approximately 200,000 locations of 47 moose over 2 yr in the Laurentides Wildlife Reserve was used as an empirical basis for the model. Twelve moose were selected from this data set and programmed in the model to forage and travel in the study area. Five parameters with an additional application of stochasticity were used to determine moose movement between forest polygons. These included food quality; cover quality, i.e., protection from predators and thermal stress; proximity to salt pools; proximity to water; and slope. There was a significant reduction in road crossings when either all or two thirds of the roadside salt pools were removed, with and/or without salt pool displacement. With 100% salt pool removal, the reduction was greater (49% without compensatory salt pools than with them (18%. When two thirds of the salt pools were removed, the reduction was the same with and without compensatory salt pools (16%. Although moose-vehicle collisions are not a significant mortality factor for the moose population in the Laurentides Wildlife Reserve, in areas with higher road densities, hunting pressure, and/or predator densities it could mean the difference between a stable and a declining population, and salt pool removal could be part of a good mitigation plan to halt population declines. This model can be used, with improvements such as

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.

Monitoring Forsmark. Moose age composition, reproduction and antler development in Haallnaes; Monitoring Forsmark. Aelgstammens aalderssammansaettning reproduktion och hornutveckling i Haallnaes

Energy Technology Data Exchange (ETDEWEB)

Cederlund, Goeran; Broman, Emil (Svensk Naturfoervaltning AB (Sweden))

2011-05-15

The moose (Alces alces) is an important game species in Haallnaes, as well as in Sweden in general. Hunting on moose is subject to strict local regulations and restrictions within a management program. Such restrictions will have considerable effects on demography. This has led to a moose population in Haallnaes with biased sex ratio with fewer adult males than females and a generally low average age. High hunting pressure on males has caused a low survival rate and the chance to survive more than five years is just a few percent. Restrictions in hunting pressure on females have caused a generally higher survival rate and a higher average age compared to males. Sex differences in body mass are normal compared to other populations in southern Sweden. Mean body mass of culled calves is an important measure of quality of the population, since it reflects the available food resources in the management area. Body mass among calves in Haallnaes is generally low, indicating a deteriorated food resource due to either ambient population density and/or hampered food production in the forest. The average reproduction rate is normal compared to other populations in this part of Sweden. However, one year old females (yearlings) have a fairly low production of eggs per female (ovulation rate). As the yearlings constitute a considerable part of the population in Haallnaes, their lowered ovulation rate will affect the rate of recruitment of calves to the local population. The moose population seems to have been subject to considerable variation in density during the last decade, which is probably a joint effect of changes in demography (hunting), changes in food resources due to forestry management and by food competition from other browsers in the area. Local managers believe that the population has reached such a low level (although not verified by surveys) that the number of moose has to be increased. It is vital to stress the importance of keeping up collection of data from

Monitoring Forsmark. Moose age composition, reproduction and antler development in Forsmark; Monitoring Forsmark. Aelgstammens aalderssammansaettning reproduktion och hornutveckling i Forsmark

Energy Technology Data Exchange (ETDEWEB)

Cederlund, Goeran; Broman, Emil (Svensk Naturfoervaltning AB (Sweden))

2011-05-15

The moose (Alces alces) is an important game species in Forsmark, as well as in Sweden in general. Hunting on moose is subject to strict local regulations and restrictions within a management program. Such restrictions will have considerable effects on demography. This has led to a moose population in Forsmark with biased sex ratio with fewer adult males than females and a generally low average age. High hunting pressure on males has caused a low survival rate and the chance to survive more than five years is just a few percent. Restrictions in hunting pressure on females have caused a generally higher survival rate and a higher average age compared to males. Sex differences in body mass are normal compared to other populations in southern Sweden. Mean body mass of culled calves is an important measure of quality of the population, since it reflects the available food resources in the management area. Body mass among calves in Forsmark is generally low, indicating a deteriorated food resource due to either ambient population density and/or hampered food production in the forest. The average reproduction rate is normal compared to other populations in this part of Sweden. However, one year old females (yearlings) have a fairly low production of eggs per female (ovulation rate). As the yearlings constitute a considerable part of the population in Forsmark, their lowered ovulation rate will affect the rate of recruitment of calves to the local population. The moose population seems to have been subject to considerable variation in density during the last decade, which is probably a joint effect of changes in demography (hunting), changes in food resources due to forestry management and by food competition from other browsers in the area. Local managers believe that the population has reached such a low level (although not verified by surveys) that the number of moose has to be increased. It is vital to stress the importance of keeping up collection of data from the

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

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....

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.

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.

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

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.

Feeding patterns of migratory and non-migratory fourth instar larvae of two coexisting Chaoborus species in an acidic and metal contaminated lake: Importance of prey ingestion rate in predicting metal bioaccumulation

Science.gov (United States)

Croteau, M.-N.; Hare, L.; Marcoux, P.

2003-01-01

We studied diel variations in the feeding habits and migratory behaviors of two coexisting Chaoborus species in an acidic and metal contaminated lake (Lake Turcotte, QC, Canada). We found that although the zooplankton community was dominated by rotifers, both Chaoborus species fed mostly on chironomids and crustaceans despite the relatively low abundance of these prey types in the lake plankton. Chaoborus americanus larvae fed on those of Chaoborus punctipennis, but not vice versa. The non-migratory species (C. americanus) fed throughout the day and night whereas the migratory species (C. punctipennis) fed only at night while in the water column. The larger-bodied C. americanus consumed more prey and had a more diverse diet than did the smaller-bodied C. punctipennis. Differences in feeding habits between the Chaoborus species inhabiting Lake Turcotte (prey biomass, prey types) likely explain in part their ability to coexist. Attempts to predict Cd in the Chaoborus species using our measurements of Cd in their prey and their prey ingestion rates met with mixed success; although we correctly predicted higher Cd concentrations for C. americanus larvae than for C. punctipennis larvae, we under-predicted absolute Cd concentrations. We suggest that studies such as ours that are based on analyses of gut contents of larvae collected at intervals of 4h or longer likely underestimate prey ingestion rates.

9 CFR 81.2 - Identification of deer, elk, and moose in interstate commerce.

Science.gov (United States)

2010-01-01

... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Identification of deer, elk, and moose in interstate commerce. 81.2 Section 81.2 Animals and Animal Products ANIMAL AND PLANT HEALTH... moose in interstate commerce. Each animal required to be identified by this subpart must have at least...

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

Pika: A snow science simulation tool built using the open-source framework MOOSE

Science.gov (United States)

Slaughter, A.; Johnson, M.

2017-12-01

The Department of Energy (DOE) is currently investing millions of dollars annually into various modeling and simulation tools for all aspects of nuclear energy. An important part of this effort includes developing applications based on the open-source Multiphysics Object Oriented Simulation Environment (MOOSE; mooseframework.org) from Idaho National Laboratory (INL).Thanks to the efforts of the DOE and outside collaborators, MOOSE currently contains a large set of physics modules, including phase-field, level set, heat conduction, tensor mechanics, Navier-Stokes, fracture and crack propagation (via the extended finite-element method), flow in porous media, and others. The heat conduction, tensor mechanics, and phase-field modules, in particular, are well-suited for snow science problems. Pika--an open-source MOOSE-based application--is capable of simulating both 3D, coupled nonlinear continuum heat transfer and large-deformation mechanics applications (such as settlement) and phase-field based micro-structure applications. Additionally, these types of problems may be coupled tightly in a single solve or across length and time scales using a loosely coupled Picard iteration approach. In addition to the wide range of physics capabilities, MOOSE-based applications also inherit an extensible testing framework, graphical user interface, and documentation system; tools that allow MOOSE and other applications to adhere to nuclear software quality standards. The snow science community can learn from the nuclear industry and harness the existing effort to build simulation tools that are open, modular, and share a common framework. In particular, MOOSE-based multiphysics solvers are inherently parallel, dimension agnostic, adaptive in time and space, fully coupled, and capable of interacting with other applications. The snow science community should build on existing tools to enable collaboration between researchers and practitioners throughout the world, and advance the

Postmortal radiographic diagnosis of laminitis in a captive European moose (Alces alces).

Science.gov (United States)

Clauss, M; Keller, A; Peemöller, A; Nygrén, K; Hatt, J-M; Nuss, K

2009-11-01

A five year-old bull moose (Alces alces) was culled due to chronic hoof overgrowth that required frequent intervention. Radiographic examination revealed changes in phalangeal bone structure usually considered indicative for laminitis in domestic cattle; similar changes were absent in the hooves of a free-ranging moose of similar age. The captive animal had been maintained in exhibits whose flooring were much harder than the soil in natural moose habitat, and on a diet with a high proportion of easily fermentable carbohydrates. These findings indicate that chronic laminitis should be considered as a potential underlying factor for hoof overgrowth, and that measures aimed at reducing the incidence of laminitis in domestic cattle, such as the use of softer flooring and diets with a higher proportion of fibre, might have prophylactic potential in captive wild ruminants.

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...

Behavior of prey links midwater and demersal piscivorous reef fishes

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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.

Continuous Integration for Concurrent MOOSE Framework and Application Development on GitHub

OpenAIRE

Slaughter, Andrew E.; Peterson, John W.; Gaston, Derek R.; Permann, Cody J.; Andrš, David; Miller, Jason M.

2015-01-01

For the past several years, Idaho National Laboratory’s MOOSE framework team has employed modern software engineering techniques (continuous integration, joint application/framework source code repos- itories, automated regression testing, etc.) in developing closed-source multiphysics simulation software (Gaston et al., 'Journal of Open Research Software' vol. 2, article e10, 2014). In March 2014, the MOOSE framework was released under an open source license on GitHub, significantly expandin...

Factors influencing caesium-137 levels in moose (Alces alces) and small game in Northern Sweden

International Nuclear Information System (INIS)

Nelin, P.; Palo, T.R.

1989-01-01

In the third annual hunting season after the Chernobyl accident the concentration of Cs-137 in meat of northern Swedish moose was significantly higher than in the first one (1986). In September 1986 the mean Cs concentration was 500 Bq/kg in calves but in September 1988 it has risen 1300 Bq/kg. This increase was only temporary and a rapid decline occured after September and by December 1988 the concentration of Cs was the same as in late 1986. Adult moose showed the same increase during the hunt 1988 but to a lower magnitude. Typical food plants of moose such as bilberry (Vaccinum myrtillus) and birch (Betula pubescens) showed, contradictory to expected by the level in moose, a decline of concentration caesium from 1986 to 1988. A probable explanation to the dramatically increased concentration of Cs in moose is a change in diet selection during 1988. Small mammals such as voles and lemmings showed a variation in concentration of caesium-137 which was more dependent on other factors than on their body size. This emphasize the necessity to study diet selection by herbivores in detail in order to predict uptake and changes in environmental contaminants. (orig.)

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

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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].

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.

Ungulate predation and ecological roles of wolves and coyotes in eastern North America.

Science.gov (United States)

Benson, John F; Loveless, Karen M; Rutledge, Linda Y; Patterson, Brent R

2017-04-01

Understanding the ecological roles of species that influence ecosystem processes is a central goal of ecology and conservation biology. Eastern coyotes (Canis latrans) have ascended to the role of apex predator across much of eastern North America since the extirpation of wolves (Canis spp.) and there has been considerable confusion regarding their ability to prey on ungulates and their ecological niche relative to wolves. Eastern wolves (C. lycaon) are thought to have been the historical top predator in eastern deciduous forests and have previously been characterized as deer specialists that are inefficient predators of moose because of their smaller size relative to gray wolves (C. lupus). We investigated intrinsic and extrinsic influences on per capita kill rates of white-tailed deer (Odocoileus virginianus) and moose (Alces alces) during winter by sympatric packs of eastern coyotes, eastern wolves, and admixed canids in Ontario, Canada to clarify the predatory ability and ecological roles of the different canid top predators of eastern North America. Eastern coyote ancestry within packs negatively influenced per capita total ungulate (deer and moose combined) and moose kill rates. Furthermore, canids in packs dominated by eastern coyote ancestry consumed significantly less ungulate biomass and more anthropogenic food than packs dominated by wolf ancestry. Similar to gray wolves in previous studies, eastern wolves preyed on deer where they were available. However, in areas were deer were scarce, eastern wolves killed moose at rates similar to those previously documented for gray wolves at comparable moose densities across North America. Eastern coyotes are effective deer predators, but their dietary flexibility and low kill rates on moose suggest they have not replaced the ecological role of wolves in eastern North America. © 2017 by the Ecological Society of America.

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

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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.

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

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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

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.

Conditions for caribou persistence in the wolf-elk-caribou systems of the Canadian Rockies

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Mark Hebblewhite

2007-04-01

Full Text Available Woodland caribou populations are considered threatened in Alberta and have declined in the Canadian Rocky Mountain National Parks of Banff and Jasper despite protection from factors causing caribou populations to decline outside of parks. Recent research emphasizes the importance of the numeric response of wolves to moose in moose-caribou-wolf systems to caribou persistence. Moose are rare in the Canadian Rockies, where the dominant ungulate prey for wolves is elk. Few studies have explored wolf-elk dynamics and none have examined implications for caribou. We used data collected in Banff to estimate the numeric response of wolves to elk from 1985 to 2005. Because no caribou kill-rate data exist for the Rockies, we explore the consequences of a range of hypothetical kill-rates based on kill-rates of alternate prey collected from 1985 to 2000 in Banff. We then multiplied the numeric response of wolves by the estimated caribou kill-rates to estimate the wolf predation response on caribou as a function of elk density. Caribou predation rates were inversely density dependent because wolf numbers depend on prey species besides caribou in multiple prey species systems. We then combined this simple wolf-elk-caribou model with observed demographic and population estimates for Banff and Jasper caribou from 2003-2004 and solved for the critical kill-rate thresholds above which caribou populations would decline. Using these critical kill-rate thresholds, Jasper caribou are likely to persist when wolf densities are below 2.1 - 4.3 wolves/1000km2 and/or when elk densities are below 0.015- 0.033 elk/km2. Thresholds for Banff caribou persistence are much lower because of inverse density dependence. Future research is needed on some of the necessary assumptions underlying our modeling including multi-prey wolf numeric responses, wolf kill-rates of caribou, caribou mortality by other predators, and spatial aspects of wolf-elk-caribou dynamics.

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.

Relationship of deer and moose populations to previous winters' snow

Science.gov (United States)

Mech, L.D.; McRoberts, R.E.; Peterson, R.O.; Page, R.E.

1987-01-01

(1) Linear regression was used to relate snow accumulation during single and consecutive winters with white-tailed deer (Odocoileus virginianus) fawn:doe ratios, mosse (Alces alces) twinning rates and calf:cow ratios, and annual changes in deer and moose populations. Significant relationships were found between snow accumulation during individual winters and these dependent variables during the following year. However, the strongest relationships were between the dependent variables and the sums of the snow accumulations over the previous three winters. The percentage of the variability explained was 36 to 51. (2) Significant relationships were also found between winter vulnerability of moose calves and the sum of the snow accumulations in the current, and up to seven previous, winters, with about 49% of the variability explained. (3) No relationship was found between wolf numbers and the above dependent variables. (4) These relationships imply that winter influences on maternal nutrition can accumulate for several years and that this cumulative effect strongly determines fecundity and/or calf and fawn survivability. Although wolf (Canis lupus L.) predation is the main direct mortality agent on fawns and calves, wolf density itself appears to be secondary to winter weather in influencing the deer and moose populations.

Prey diversity for Three Species Herons in Pulau Dua Nature Reserve Serang Distrik, Banten Province

Directory of Open Access Journals (Sweden)

DEWI ELFIDASARI

2006-10-01

Full Text Available The diversity of prey consumed by three species herons (Casmerodius albus, Egretta garzetta and Bubulcus ibis was studied in Pulau Dua Nature Reserve Serang, Banten Province using video tapes by following a focal individual for five minutes. In the laboratory the film was analysed every minutes to select complete sequences of feeding behavior in foraging site. There were differences on diversity and size of prey that consumed by three species herons among the different feeding locations. Casmerodius albus which was feeding on mudflat and fisheries consumed Chanos chanos (15.6%, Oreochromis sp (9.4% and Periophtalmus sp. (7.3%, and 36.5% couldn’t be identified. Egretta garzetta was feeding on mudflat, fisheries and rice-field, consumed Periophtalmus sp (15.4%, Mugil dussumeieri (7.9%, Chanos chanos (4.7%, Oreochromis sp (0.5%, including small frog and crustacean (0.5%. Bubulcus ibis was feeding on rice-field and grassland, consumed many variety of insects (92 % and many variety of snail (1.9% in their diet. The insects that B. ibis consumed including grasshopper (26.8%, caterpillar (0.9% and other invertebrates (worm, crustacean that could not be identified (64.3%.

Population ecology of two woodland caribou herds in the southern Yukon

Directory of Open Access Journals (Sweden)

Richard Farnell

1996-01-01

Full Text Available Since the mid 1980's, the Aishihik herd of woodland caribou (Rangifer tarandus caribou declined from approximately 1500 to 583 animals. During the same period a nearby herd, the Wolf Lake Herd increased from approximately 664 to 1249 animals. This paper compares aspects of the ecology of these two herds to determine how these relationships conform to a general model of caribou population ecology described by Seip (1992. Comparisons include caribou demographic characteristics and distribution patterns, predator densities, abundance of alternate prey, human hunting and snow depth on caribou winter range. Ecological differences between herds were apparent in the ratio of prime bulls to cows, the abundance of moose (Alces alces, the occurrence of coyotes (Canis latrans, late winter snow conditions, and access to hunting. We hypothesize that the Wolf Lake herd was able to grow because wolves {Canis lupus preyed mainly on the relatively abundant moose population. A highly clumped winter caribou distribution may have further reduced the impact of wolf predation on the Wolf Lake herd. In contrast, the decline of the Aishihik herd was accompanied by a relative scarcity of moose, few prime aged caribou bulls probably due to a more liberal trophy harvest, and wider late-winter dispersion that offered wolves greater access to caribou. The decline may have been exaggerated by the peak in the snowshoe hare (Lepus americanus cycle which may have temporarily improved wolf pup survival. We suspect that moose are normally the primary prey of wolves in the Yukon and that a decline in moose eventually results in their being too scarce to offer an economical prey choice, prompting a prey switch to caribou. Results of our analyses conform incompletely to Seip's (1992 model for woodland caribou population ecology, particularly because the Wolf Lake herd prospered where moose were relatively abundant.

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

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.

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.

Incorporating Road Crossing Data into Vehicle Collision Risk Models for Moose (Alces americanus) in Massachusetts, USA.

Science.gov (United States)

Zeller, Katherine A; Wattles, David W; DeStefano, Stephen

2018-05-09

Wildlife-vehicle collisions are a human safety issue and may negatively impact wildlife populations. Most wildlife-vehicle collision studies predict high-risk road segments using only collision data. However, these data lack biologically relevant information such as wildlife population densities and successful road-crossing locations. We overcome this shortcoming with a new method that combines successful road crossings with vehicle collision data, to identify road segments that have both high biological relevance and high risk. We used moose (Alces americanus) road-crossing locations from 20 moose collared with Global Positioning Systems as well as moose-vehicle collision (MVC) data in the state of Massachusetts, USA, to create multi-scale resource selection functions. We predicted the probability of moose road crossings and MVCs across the road network and combined these surfaces to identify road segments that met the dual criteria of having high biological relevance and high risk for MVCs. These road segments occurred mostly on larger roadways in natural areas and were surrounded by forests, wetlands, and a heterogenous mix of land cover types. We found MVCs resulted in the mortality of 3% of the moose population in Massachusetts annually. Although there have been only three human fatalities related to MVCs in Massachusetts since 2003, the human fatality rate was one of the highest reported in the literature. The rate of MVCs relative to the size of the moose population and the risk to human safety suggest a need for road mitigation measures, such as fencing, animal detection systems, and large mammal-crossing structures on roadways in Massachusetts.

Oil and gas development and the potential for contamination of moose (Alces alces) in northeast BC

International Nuclear Information System (INIS)

Maundrell, C.; Roe, N.

2007-01-01

Traditional sources of food for meat, berries, and fish are relied upon by First Nations of northern Canada. Hunting and trapping in traditional areas are the primary sources of protein consumption by First Nations. In the Northwest Territories and northeast British Columbia (BC), moose meat (Alces alces) is one of the most sought after meats. Therefore, an important consideration needing documentation was to determine if animals in areas of high oil and gas development were unhealthy compared to animals living in areas of low or no oil and gas activity. This paper presented the results of a study that documented the presence of contaminants in harvested moose. The main purpose of the study was to analyze moose tissue samples for extractable petroleum hydrocarbons, heavy metals and polycyclic hydrocarbons. The paper also discussed the methodology used in harvesting the moose which involved shooting them with a high powered rifle to collect tissue samples. Levels of concentration in tissues between two areas with noticeably different levels of oil and gas activity were then compared. Significantly higher levels of heavy metal concentrations were found in tissues sampled from the treatment area. It was therefore concluded that oil and gas activity may have negative impacts on the health of moose in northeast BC. 8 refs., 2 tabs

The impact of tannins on protein, dry matter, and energy digestion in moose (Alces alces)

Science.gov (United States)

Donald E. Spalinger; W.B. Collins; Thomas A. Hanley; N.E. Cassara; A.M. Carnahan

2010-01-01

Recent work suggests that moose (Alces alces [L., 1758]) in the boreal ecoregion may be nutritionally limited by the availability of protein as a consequence of both low nitrogen (N) concentrations and high tannin levels in their principal foods. However, the ability of moose to digest protein in the presence of tannins is unknown. We undertook a...

Chemical and structural composition of Atlantic Canadian moose (Alces alces) incisors with patterns of high breakage

Energy Technology Data Exchange (ETDEWEB)

MacKenzie, Cynthia S. Kendall; Clough, Michael J. [Biology Department, Saint Mary' s University, Halifax, Nova Scotia, Canada B3H 3C3 (Canada); Broders, Hugh G., E-mail: hugh.broders@smu.ca [Biology Department, Saint Mary' s University, Halifax, Nova Scotia, Canada B3H 3C3 (Canada); Tubrett, Mike [Inco Innovation Centre, ICP-MS Facility, Memorial University of Newfoundland, P.O. Box 4200, St. John' s, Newfoundland, Canada A1C 5S7 (Canada)

2011-11-15

Analysis of mammalian teeth can provide information regarding local environmental conditions. For example, a high incidence of breakage and wear within a population may indicate poor food quality. Individuals consuming a diet causing high mechanical stress on their teeth, and/or lacking the appropriate minerals for proper development, could experience degradation of tooth condition. Previously, we documented a high rate of incisor tooth breakage, with age, in two genetically distinct moose populations in Atlantic Canada. In this study, multi-element ({sup 11}B, {sup 63}Cu, {sup 64}Zn, {sup 75}As, {sup 85}Rb, {sup 88}Sr, {sup 111}Cd, {sup 118}Sn, {sup 137}Ba, {sup 208}Pb, {sup 232}Th, and {sup 238}U) analyses using laser ablation ICP-MS were performed on moose incisors from multiple North American regions. The purpose was to determine whether the elemental composition of moose incisors varies among regions, and whether that variation is related to tooth degradation among Atlantic Canadian populations. A principal components analysis revealed that nearly 50% of the elemental variation in the inner enamel matrix of moose teeth was explained by three groupings of elements. The element groupings revealed differences among geographic regions, but did not explain the variation between incisors that were broken and those that were not. Regression models indicate that the elemental group which includes Cu, Pb, and Zn is related to decreases in incisal integrity. It is likely that other environmental factors contribute to the occurrence of increased incisor breakage in affected populations. The relationship between food resource quantity and quality, as a function of moose density, is hypothesized to explain loss of tooth integrity. - Highlights: {yields} Multi-element analysis of 1300 moose incisors using laser ablation ICP-MS. {yields} Three element groupings explain 50% of tooth composition variation among regions. {yields} Regional differences in tooth composition

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.

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.

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.

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.

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...

Bull Moose Tube Company - Clean Water Act Public Notice

Science.gov (United States)

The EPA is providing notice of a proposed Administrative Penalty Assessment against the Bull Moose Tube Company, a business located at 1819 Clarkson Road, Chesterfield, MO, 63017, for alleged violations at the facility located at 406 East Industrial Drive,

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. 

Conservation of wildlife populations: factoring in incremental disturbance.

Science.gov (United States)

Stewart, Abbie; Komers, Petr E

2017-06-01

Progressive anthropogenic disturbance can alter ecosystem organization potentially causing shifts from one stable state to another. This potential for ecosystem shifts must be considered when establishing targets and objectives for conservation. We ask whether a predator-prey system response to incremental anthropogenic disturbance might shift along a disturbance gradient and, if it does, whether any disturbance thresholds are evident for this system. Development of linear corridors in forested areas increases wolf predation effectiveness, while high density of development provides a safe-haven for their prey. If wolves limit moose population growth, then wolves and moose should respond inversely to land cover disturbance. Using general linear model analysis, we test how the rate of change in moose ( Alces alces ) density and wolf ( Canis lupus ) harvest density are influenced by the rate of change in land cover and proportion of land cover disturbed within a 300,000 km 2 area in the boreal forest of Alberta, Canada. Using logistic regression, we test how the direction of change in moose density is influenced by measures of land cover change. In response to incremental land cover disturbance, moose declines occurred where 43% of land cover was disturbed and wolf density declined. Wolves and moose appeared to respond inversely to incremental disturbance with the balance between moose decline and wolf increase shifting at about 43% of land cover disturbed. Conservation decisions require quantification of disturbance rates and their relationships to predator-prey systems because ecosystem responses to anthropogenic disturbance shift across disturbance gradients.

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...

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.

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...

Anti-Brucella Antibodies in Moose (Alces alces gigas), Muskoxen (Ovibos moschatus), and Plains Bison (Bison bison bison) in Alaska, USA.

Science.gov (United States)

Nymo, Ingebjørg Helena; Beckmen, Kimberlee; Godfroid, Jacques

2016-01-01

We used an indirect enzyme-linked immunosorbent assay (iELISA) and the rose bengal test (RBT) to test for anti-Brucella antibodies in moose (Alces alces gigas), muskoxen (Ovibos moschatus), and plains bison (Bison bison bison) from various game management units (GMUs) in Alaska, US, sampled from 1982 to 2010. A portion of the sera had previously been tested with the standard plate test (SPT), the buffered Brucella antigen (BBA) card test, and the card test (CARD). No antibody-positive plains bison were identified. Anti-Brucella antibodies were detected in moose (iELISA, n=4/87; RBT, n=4/87; SPT, n=4/5; BBA, n=4/4) from GMU 23 captured in 1992, 1993, and 1995 and in muskoxen (iELISA, n=4/52; RBT, n=4/52; CARD, n=4/35) from GMUs 26A and 26B captured in 2004, 2006, and 2007. A negative effect of infection on the health of individuals of these species is probable. The presence of antibody-positive animals from 1992 to 2007 suggests presence of brucellae over time. The antibody-positive animals were found in northern Alaska, an area with a historically higher prevalence of Brucella-positive caribou, and a spillover of Brucella suis biovar 4 from caribou may have occurred. Brucella suis biovar 4 causes human brucellosis, and transmission from consumption of moose and muskoxen is possible.

Prey diversity is associated with weaker consumer effects in a meta-analysis of benthic marine experiments.

Science.gov (United States)

Edwards, Kyle F; Aquilino, Kristin M; Best, Rebecca J; Sellheim, Kirsten L; Stachowicz, John J

2010-02-01

A rapidly accumulating body of research has shown that species diversity consistently affects the functioning of ecosystems. The incorporation of trophic complexity and the extension of this research to larger scales and natural ranges in species diversity remain as important challenges for understanding the true magnitude of these effects in natural systems. Here, we test whether the diversity of prey communities affects the magnitude of aggregate consumer effects. We conducted a meta-analysis of 57 consumer removal field experiments from a range of intertidal and subtidal hard substrate marine communities. We found that the richness of the prey community was the strongest predictor of the magnitude of consumer effects while controlling for habitat type, taxonomic composition, and other variables. Consumer removal increased aggregate prey abundance on average by 1200% at the lower limit of prey diversity (two species), but only 200% at the upper limit of 37 species. Importantly, compositional change was substantial at both high and low prey diversity, suggesting predation intensity did not vary with prey richness. Rather diverse prey communities appear to be more capable of maintaining abundance via compensatory responses, by containing prey species that are resistant to (or tolerant of) predators. These results suggest that the effects of species diversity on trophic interactions may scale consistently from small-scale manipulations to cross-community comparisons.

Perspectives on sustainable development in the Moose River basin

Energy Technology Data Exchange (ETDEWEB)

Preston, R.J.; George, P.J. [McMaster Univ., Hamilton, ON (Canada); Berkes, F. [Manitoba Univ., Winnipeg, MB (Canada)

1995-12-31

The environmental, economic and sociocultural determinants of sustainable development in the Cree communities of the Mushkegowuk region of the Hudson and James Bay lowlands of Ontario were analyzed. The Cree perspectives on sustainable development versus the perspective of industrial developers such as Ontario Hydro, and the contrast between the two, were outlined. In 1990, Ontario Hydro released their long term demand and supply plan report. Their proposals included new generating stations and the development of existing sites in the Moose River drainage basin. Ontario Hydro`s perspective was that they were using an otherwise under-utilized resource, and creating employment at the same time. By contrast, the Cree demanded a thorough assessment of cumulative impacts of development of the Moose River region, the impact on the Cree communities, and the cumulative effects on the much larger Hudson Bay region. They drew attention to the vulnerability of the local land-based economy, and the damage caused by past hydroelectric and other industrial development projects. The situation is a good illustration of the basic dilemma for development planning in the Moose River region, and indeed for much of the Canadian north. It is the view of these authors that the recipe for a viable development strategy for the region should involve continued reliance on transfer payments and investments in renewable resource-based industry and local services, not as a transition stage, but as a culturally, economically and ecologically sustainable arrangement in its own right. 32 refs., 1 tab., 2 figs.

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

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 ...

A community-level evaluation of the impact of prey behavioural and ecological characteristics on predator diet composition.

Science.gov (United States)

Shultz, Susanne; Noë, Ronald; McGraw, W Scott; Dunbar, R I M

2004-04-07

Although predation avoidance is the most commonly invoked explanation for vertebrate social evolution, there is little evidence that individuals in larger groups experience lower predation rates than those in small groups. We compare the morphological and behavioural traits of mammal prey species in the Taï forest, Ivory Coast, with the diet preferences of three of their non-human predators: leopards, chimpanzees and African crowned eagles. Individual predators show marked differences in their predation rates on prey species of different body sizes, but clear patterns with prey behaviour were apparent only when differences in prey habitat use were incorporated into the analyses. Leopard predation rates are highest for terrestrial species living in smaller groups, whereas eagle predation rates are negatively correlated with group size only among arboreal prey. When prey predation rates are summed over all three predators, terrestrial species incur higher predation rates than arboreal species and, within both categories, predation rates decline with increasing prey group size and decreasing density of groups in the habitat. These results reveal that it is necessary to consider anti-predator strategies in the context of a dynamic behavioural interaction between predators and prey.

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

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 ...

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.

Fatty acids in six small pelagic fish species and their crustacean prey from the mindanao sea, southern Philippines.

Science.gov (United States)

Metillo, Ephrime Bicoy; Aspiras-Eya, Anna Arlene

2014-08-01

Fatty acids are important in human health and useful in the analysis of the marine food web, however information on tropical pelagic organisms is scarce. Six zooplanktivorous small pelagic fish species (Decapterus kurroides, Decapterus macarellus, Selar crumenophthalmus, Sardinella lemuru, Spratilloides gracilis and Stolephorus insularis) and four of their zooplanktonic crustacean prey [three sergestoid species (Acetes erythraeus, Acetes intermedius and Lucifer penicillifer) and one calanoid copepod (Acartia erythraea)] were collected from the Mindanao Sea, and their fatty acids were profiled. The resulting profiles revealed 17 fatty acids that were specific to certain species and 9 {myristic acid [C14:0], palmitic acid [C16:0], stearic acid [C18:0]; palmitoleic acid [C16:1], oleic acid [C18:1n9c], linoleic acid [C18:2n6c], linolenic acid [C18:3n3], eicosapentaenoic acid (EPA) [C20:5n3] and docosahexaenoic acid (DHA) [C22:6n3]} that were common to all species. Cluster analysis and non-metric multidimensional scaling (NMDS) of fatty acids indicate a high similarity in profiles in all species, but separate fish and zooplankton clusters were obtained. Mackerel species (D. macarellus, D. kurroides and S. crumenophthalmus) had concentrations of total n-3 fatty acids that match those of their Acetes prey. The copepod A. erythraea and the sergestoid L. penicillifer exhibited the lowest values of the EPA:DHA ratio, which was most likely due to their phytoplanktivorous feeding habits, but the occurrence of the highest values of the ratio in Acetes suggests the inclusion of plant detritus in their diet. DHA values appear to affirm the trophic link among copepod, Lucifer, Acetes and mackerel species.

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.

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

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

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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.

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.

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

M3MS-16OR0401086 – Report on NEAMS Workbench Support for MOOSE Applications

Energy Technology Data Exchange (ETDEWEB)

Lefebvre, Robert A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division; Langley, Brandon R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division; Thompson, Adam B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division

2016-09-23

This report summarizes the status of the Nuclear Energy Advanced Modeling and Simulation (NEAMS) Workbench from Oak Ridge National Laboratory (ORNL) and the integration of the MOOSE framework. This report marks the completion of NEAMS milestone M3MS-16OR0401086. This report documents the developed infrastructure to support the MOOSE framework applications, the applications’ results, visualization status, the collaboration that facilitated this progress, and future considerations.

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)

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

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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.

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)

Trait-based diet selection: prey behaviour and morphology predict vulnerability to predation in reef fish communities.

Science.gov (United States)

Green, Stephanie J; Côté, Isabelle M

2014-11-01

Understanding how predators select their prey can provide important insights into community structure and dynamics. However, the suite of prey species available to a predator is often spatially and temporally variable. As a result, species-specific selectivity data are of limited use for predicting novel predator-prey interactions because they are assemblage specific. We present a method for predicting diet selection that is applicable across prey assemblages, based on identifying general morphological and behavioural traits of prey that confer vulnerability to predation independent of species identity. We apply this trait-based approach to examining prey selection by Indo-Pacific lionfish (Pterois volitans and Pterois miles), invasive predators that prey upon species-rich reef fish communities and are rapidly spreading across the western Atlantic. We first generate hypotheses about morphological and behavioural traits recurring across fish species that could facilitate or deter predation by lionfish. Constructing generalized linear mixed-effects models that account for relatedness among prey taxa, we test whether these traits predict patterns of diet selection by lionfish within two independent data sets collected at different spatial scales: (i) in situ visual observations of prey consumption and availability for individual lionfish and (ii) comparisons of prey abundance in lionfish stomach contents to availability on invaded reefs at large. Both analyses reveal that a number of traits predicted to affect vulnerability to predation, including body size, body shape, position in the water column and aggregation behaviour, are important determinants of diet selection by lionfish. Small, shallow-bodied, solitary fishes found resting on or just above reefs are the most vulnerable. Fishes that exhibit parasite cleaning behaviour experience a significantly lower risk of predation than non-cleaning fishes, and fishes that are nocturnally active are at significantly

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…

Artificial night light alters nocturnal prey interception outcomes for morphologically variable spiders

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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.

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.

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.

Selective Predation of a Stalking Predator on Ungulate Prey.

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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.

Prey aggregation is an effective olfactory predator avoidance strategy

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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.

Physiological evaluation of free-ranging moose (Alces alces immobilized with etorphine-xylazine-acepromazine in Northern Sweden

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Evans Alina L

2012-12-01

Full Text Available Abstract Background Evaluation of physiology during capture and anesthesia of free-ranging wildlife is useful for determining the effect that capture methods have on both ecological research results and animal welfare. This study evaluates capture and anesthesia of moose (Alces alces with etorphine-xylazine-acepromazine in Northern Sweden. Methods Fifteen adult moose aged 3–15 years were darted from a helicopter with a combination of 3.37 mg etorphine, 75 mg xylazine, and 15 mg acepromazine. Paired arterial blood samples were collected 15 minutes apart with the first sample at 15–23 minutes after darting and were analyzed immediately with an i-STAT®1 Portable Clinical Analyzer. Results All animals developed hypoxemia (PaO2 2 5.5-8 kPa. All moose were acidemic (ph2, 14 moose had mild hypercapnia (PaCO2 6-8 kPa and two had marked hypercapnia (PaCO2>8 kPa. Pulse, respiratory rate, pH and HCO3 increased significantly over time from darting whereas lactate decreased. Conclusions The hypoxemia found in this study is a strong indication for investigating alternative drug doses or combinations or treatment with supplemental oxygen.

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....

Echolocating bats cry out loud to detect their prey.

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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

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...

Species diversity modulates predation

NARCIS (Netherlands)

Kratina, P.; Vos, M.; Anholt, B.R.

2007-01-01

Predation occurs in a context defined by both prey and non-prey species. At present it is largely unknown how species diversity in general, and species that are not included in a predator's diet in particular, modify predator–prey interactions.Therefore we studied how both the density and diversity

Prey selection of lions Panthera leo in a small, enclosed reserve

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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

Orthopteran insects as potential and preferred preys of the Red-footed Falcon (Falco vespertinus in Hungary

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Szövényi Gergely

2015-06-01

Full Text Available Orthopterans play an important role in Red-footed Falcon diet, however, most studies focus only on its qualitative food composition, and less on quantitative composition and preferences of the taxa identified as prey. During the present research, an extensive orthopterological investigation was carried out in the Red-footed Falcon study area, Vásárhelyi Plain (SE-Hungary between 2006 and 2008. Grasshoppers were sampled in their main habitats by sweep netting and pitfall trapping, and orthopterans were identified in the food remnants collected from the nests, both artificial and natural ones. 26 species were detected during the field works, 18 species from the food remnants. Altogether 32 species were identified. Prey preference values for all species for each year were calculated. More than two thirds of the identified preys were Decticus verrucivorus, and nearly 20% were Tettigonia viridissima. Other common prey species were Melanogryllus desertus, Platycleis affinis, Gryllotalpa gryllotalpa, Calliptamus italicus and Gryllus campestris. Based on the prey preference analysis, the most preferred species was Decticus verrucivorus with extreme high values, and the other preferred ones, overlapping with the previous list, were Platycleis affinis, Bicolorana bicolor, Tettigonia viridissima, Calliptamus italicus and Roeseliana roeselii. These results may help in the development of Red-footed Falcon-friendly habitats through the application of habitat management favourable for the preferred prey species.

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).

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.

Wild North Island Robins (Petroica longipes respond to Prey Animacy

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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.

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

Reducing Moose-Vehicle Collisions through Salt Pool Removal and Displacement: an Agent-Based Modeling Approach

OpenAIRE

Paul D. Grosman; Jochen A. G. Jaeger; Pascale M. Biron; Christian Dussault; Jean-Pierre Ouellet

2009-01-01

Between 1990 and 2002, more than 200 moose-vehicle collisions occurred each year in Quebec, including about 50/yr in the Laurentides Wildlife Reserve. One cause is the presence of roadside salt pools that attract moose near roads in the spring and summer. Using the computer simulation technique of agent-based modeling, this study investigated whether salt pool removal and displacement, i.e., a compensatory salt pool set up 100 to 1500 m away from the road shoulder, would reduce the number of ...

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

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

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...

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.

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.

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).

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

Managing for Caribou Survival in a Partitioned Habitat

Directory of Open Access Journals (Sweden)

H.G. Cumming

1996-01-01

Full Text Available Forest management guidelines for woodland caribou (Rangifer tarandus caribou in Ontario need to be re-examined in light of the finding that caribou partition habitat with moose (Alces alces, partly to find virtual refuges from predation by gray wolves (Canis lupus. Forest-wide guidelines seem inappropriate for a species that is widely scattered and little known. Management should concentrate on and around currently used virtual refuges to ensure their continued habitability. Cutting these areas may force the caribou into places with higher densities of predators; winter use of roads might bring poachers, increased wolf entry, and accidents. A proposal for 100 km2 clear-cuts scheduled over 60+ years across the forest landscape would probably minimize moose/wolf densities in the long run as intended, but because of habitat partitioning might forfeit any benefits to caribou in the short-term. Sharply reducing moose densities near areas where caribou have sought refuge might incline wolves to switch to caribou. Cutting beyond caribou winter refuge areas should aim at maintaining current moose densities to prevent wolves from switching prey species. Operations level manipulation of the forest around each wintering area should provide winter habitat for the future, while treatment replications with controls across the whole forest would provide reliable knowledge about which approaches work best. The remainder of the forest should be managed to maintain suitable densities of all other species.

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.

Seabirds maintain offspring provisioning rate despite fluctuations in prey abundance: A multi-species functional response for guillemots in the North Sea

DEFF Research Database (Denmark)

Smout, Sophie; Rindorf, Anna; Wanless, Sarah

2013-01-01

1. Seabirds that consume more than one prey type may adjust their foraging to maintain provisioning rates for their chicks. How energetically effective are these strategies, and what are the implications for the management of seabirds and their marine habitat? 2. A multi-species functional respon...

MOOSE Implementation of MAMBA

Energy Technology Data Exchange (ETDEWEB)

Galloway, Jack [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Matthews, Topher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-01-17

The development of MAMBA is targeted at capturing both core wide CRUD induced power shifts (CIPS) as well as pin-­level CRUD induced localized corrosion (CILC). Both CIPS and CILC require some sort of information from thermal-­hydraulic, neutronics, and fuel performance codes, although the degree of coupling is different for the two effects. Since CIPS necessarily requires a core-­wide power distribution solve, it requires tight coupling with a neutronics code. Conversely, CIPS tends to be an individual pin phenomenon, requiring tight coupling a fuel performance code. As efforts are now focused on coupling MAMBA within the VERA suite, a natural separation has surfaced in which a FORTRAN rewrite of MAMBA is optimal for VERA integration to capture CIPS behavior, while a CILC focused calculation would benefit from a tight coupling with BISON, motivating a MOOSE version of MAMBA.

Radionuclides and trace metals in Canadian moose near uranium mines: comparison of radiation doses and food chain transfer with cattle and caribou.

Science.gov (United States)

Thomas, Patricia; Irvine, James; Lyster, Jane; Beaulieu, Rhys

2005-05-01

Tissues from 45 moose and 4 cattle were collected to assess the health of country foods near uranium mines in northern Saskatchewan. Bone, liver, kidney, muscle and rumen contents were analyzed for uranium, radium-226 (226Ra), lead-210 (210Pb), and polonium-210 (210Po). Cesium-137 (137Cs), potassium-40 (40K), and 27 trace metals were also measured in some tissues. Within the most active mining area, Po in liver and muscle declined significantly with distance from tailings, possibly influenced by nearby natural uranium outcrops. Moose from this area had significantly higher 226Ra, 210Pb, 210Po, and 137Cs in some edible soft tissues vs. one control area. However, soil type and diet may influence concentrations as much as uranium mining activities, given that a) liver levels of uranium, 226Ra, and 210Po were similar to a second positive control area with mineral-rich shale hills and b) 210Po was higher in cattle kidneys than in all moose. Enhanced food chain transfer from rumen contents to liver was found for selenium in the main mining area and for copper, molybdenum and cadmium in moose vs. cattle. Although radiological doses to moose in the main mining area were 2.6 times higher than doses to control moose or cattle, low moose intakes yielded low human doses (0.0068 mSv y(-1)), a mere 0.3% of the dose from intake of caribou (2.4 mSv y(-1)), the dietary staple in the area.

Prey fish returned to Forster's tern colonies suggest spatial and temporal differences in fish composition and availability.

Science.gov (United States)

Peterson, Sarah H; Ackerman, Joshua T; Eagles-Smith, Collin A; Herzog, Mark P; Hartman, C Alex

2018-01-01

Predators sample the available prey community when foraging; thus, changes in the environment may be reflected by changes in predator diet and foraging preferences. We examined Forster's tern (Sterna forsteri) prey species over an 11-year period by sampling approximately 10,000 prey fish returned to 17 breeding colonies in south San Francisco Bay, California. We compared the species composition among repeatedly-sampled colonies (≥ 4 years), using both relative species abundance and the composition of total dry mass by species. Overall, the relative abundances of prey species at seven repeatedly-sampled tern colonies were more different than would be expected by chance, with the most notable differences in relative abundance observed between geographically distant colonies. In general, Mississippi silverside (Menidia audens) and topsmelt silverside (Atherinops affinis) comprised 42% of individuals and 40% of dry fish mass over the study period. Three-spined stickleback (Gasterosteus aculeatus) comprised the next largest proportion of prey species by individuals (19%) but not by dry mass (6%). Five additional species each contributed ≥ 4% of total individuals collected over the study period: yellowfin goby (Acanthogobius flavimanus; 10%), longjaw mudsucker (Gillichthys mirabilis; 8%), Pacific herring (Clupea pallasii; 6%), northern anchovy (Engraulis mordax; 4%), and staghorn sculpin (Leptocottus armatus; 4%). At some colonies, the relative abundance and biomass of specific prey species changed over time. In general, the abundance and dry mass of silversides increased, whereas the abundance and dry mass of three-spined stickleback and longjaw mudsucker decreased. As central place foragers, Forster's terns are limited in the distance they forage; thus, changes in the prey species returned to Forster's tern colonies suggest that the relative availability of some fish species in the environment has changed, possibly in response to alteration of the available habitat.

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.

Effects of climate and plant phenology on recruitment of moose at the southern extent of their range

Science.gov (United States)

Monteith, Kevin L.; Klaver, Robert W.; Hersey, Kent R.; Holland, A. Andrew; Thomas, Timothy P.; Kauffman, Matthew J.

2015-01-01

Climate plays a fundamental role in limiting the range of a species, is a key factor in the dynamics of large herbivores, and is thought to be involved in declines of moose populations in recent decades. We examined effects of climate and growing-season phenology on recruitment (8–9 months old) of young Shiras moose (Alces alces shirasi) over three decades, from 18 herds, across a large geographic area encompassing much of the southern extent of their range. Recruitment declined in 8 of 18 herds during 1980–2009, whereas others did not exhibit a temporal trend (none showed a positive trend). During those three decades, seasonal temperatures increased, spring–summer precipitation decreased, and spring occurred earlier, became shorter in duration, and green-up occurred faster. Recruitment was influenced negatively by warm temperatures during the year before young were born, but only for herds with declining recruitment. Dry spring–summers of the previous year and rapid rates of spring green-up in the year of birth had similar negative influences across declining and stable herds. Those patterns indicate both direct (year t ) and delayed (year t−1) effects of weather and plant phenology on recruitment of young, which we hypothesize was mediated through effects on maternal nutritional condition. Suppressed nutrition could have been induced by (1) increased thermoregulatory costs associated with warming temperatures and (2) shortened duration of availability of high-quality forage in spring. Progressive reductions in net energetic gain for species that are sensitive to climate may continue to hamper individual fitness and population dynamics.

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 ...

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 ...

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.

MASTODON: A geosciences simulation tool built using the open-source framework MOOSE

Science.gov (United States)

Slaughter, A.

2017-12-01

The Department of Energy (DOE) is currently investing millions of dollars annually into various modeling and simulation tools for all aspects of nuclear energy. An important part of this effort includes developing applications based on the open-source Multiphysics Object Oriented Simulation Environment (MOOSE; mooseframework.org) from Idaho National Laboratory (INL).Thanks to the efforts of the DOE and outside collaborators, MOOSE currently contains a large set of physics modules, including phase field, level set, heat conduction, tensor mechanics, Navier-Stokes, fracture (extended finite-element method), and porous media, among others. The tensor mechanics and contact modules, in particular, are well suited for nonlinear geosciences problems. Multi-hazard Analysis for STOchastic time-DOmaiN phenomena (MASTODON; https://seismic-research.inl.gov/SitePages/Mastodon.aspx)--a MOOSE-based application--is capable of analyzing the response of 3D soil-structure systems to external hazards with current development focused on earthquakes. It is capable of simulating seismic events and can perform extensive "source-to-site" simulations including earthquake fault rupture, nonlinear wave propagation, and nonlinear soil-structure interaction analysis. MASTODON also includes a dynamic probabilistic risk assessment capability that enables analysts to not only perform deterministic analyses, but also easily perform probabilistic or stochastic simulations for the purpose of risk assessment. Although MASTODON has been developed for the nuclear industry, it can be used to assess the risk for any structure subjected to earthquakes.The geosciences community can learn from the nuclear industry and harness the enormous effort underway to build simulation tools that are open, modular, and share a common framework. In particular, MOOSE-based multiphysics solvers are inherently parallel, dimension agnostic, adaptive in time and space, fully coupled, and capable of interacting with other

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

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.

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.

Demonstration of finite element simulations in MOOSE using crystallographic models of irradiation hardening and plastic deformation

Energy Technology Data Exchange (ETDEWEB)

Patra, Anirban [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wen, Wei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez Saez, Enrique [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tome, Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-05-31

This report describes the implementation of a crystal plasticity framework (VPSC) for irradiation hardening and plastic deformation in the finite element code, MOOSE. Constitutive models for irradiation hardening and the crystal plasticity framework are described in a previous report [1]. Here we describe these models briefly and then describe an algorithm for interfacing VPSC with finite elements. Example applications of tensile deformation of a dog bone specimen and a 3D pre-irradiated bar specimen performed using MOOSE are demonstrated.

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.

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...

A genetic discontinuity in moose (Alces alces) in Alaska corresponds with fenced transportation infrastructure

Science.gov (United States)

Wilson, Robert E.; Farley, Sean D.; McDonough, Thomas J.; Talbot, Sandra L.; Barboza, Perry S.

2015-01-01

The strength and arrangement of movement barriers can impact the connectivity among habitat patches. Anthropogenic barriers (e.g. roads) are a source of habitat fragmentation that can disrupt these resource networks and can have an influence on the spatial genetic structure of populations. Using microsatellite data, we evaluated whether observed genetic structure of moose (Alces alces) populations were associated with human activities (e.g. roads) in the urban habitat of Anchorage and rural habitat on the Kenai Peninsula, Alaska. We found evidence of a recent genetic subdivision among moose in Anchorage that corresponds to a major highway and associated infrastructure. This subdivision is most likely due to restrictions in gene flow due to alterations to the highway (e.g. moose-resistant fencing with one-way gates) and a significant increase in traffic volume over the past 30 years; genetic subdivision was not detected on the Kenai Peninsula in an area not bisected by a major highway. This study illustrates that anthropogenic barriers can substructure wildlife populations within a few generations and highlights the value of genetic assessments to determine the effects on connectivity among habitat patches in conjunction with behavioral and ecological data..

Bats without borders: Predators learn novel prey cues from other predatory species.

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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.

Prey fish returned to Forster’s tern colonies suggest spatial and temporal differences in fish composition and availability

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Peterson, Sarah; Ackerman, Joshua T.; Eagles-Smith, Collin A.; Herzog, Mark; Hartman, C. Alex

2018-01-01

Predators sample the available prey community when foraging; thus, changes in the environment may be reflected by changes in predator diet and foraging preferences. We examined Forster’s tern (Sterna forsteri) prey species over an 11-year period by sampling approximately 10,000 prey fish returned to 17 breeding colonies in south San Francisco Bay, California. We compared the species composition among repeatedly-sampled colonies (≥ 4 years), using both relative species abundance and the composition of total dry mass by species. Overall, the relative abundances of prey species at seven repeatedly-sampled tern colonies were more different than would be expected by chance, with the most notable differences in relative abundance observed between geographically distant colonies. In general, Mississippi silverside (Menidia audens) and topsmelt silverside (Atherinops affinis) comprised 42% of individuals and 40% of dry fish mass over the study period. Three-spined stickleback (Gasterosteus aculeatus) comprised the next largest proportion of prey species by individuals (19%) but not by dry mass (6%). Five additional species each contributed ≥ 4% of total individuals collected over the study period: yellowfin goby (Acanthogobius flavimanus; 10%), longjaw mudsucker (Gillichthys mirabilis; 8%), Pacific herring (Clupea pallasii; 6%), northern anchovy (Engraulis mordax; 4%), and staghorn sculpin (Leptocottus armatus; 4%). At some colonies, the relative abundance and biomass of specific prey species changed over time. In general, the abundance and dry mass of silversides increased, whereas the abundance and dry mass of three-spined stickleback and longjaw mudsucker decreased. As central place foragers, Forster’s terns are limited in the distance they forage; thus, changes in the prey species returned to Forster’s tern colonies suggest that the relative availability of some fish species in the environment has changed, possibly in response to alteration of the available

Taxonomic status of Cyathostoma nematodes (Nematoda: Syngaminae parasitizing respiratory tracts of birds of prey and owls in Europe and North America: how many species are there?

Directory of Open Access Journals (Sweden)

Kanarek G.

2016-03-01

Full Text Available So far, the identity of Cyathostoma (Hovorkonema nematodes collected from respiratory tracts of birds of prey (Accipitriformes, Falconiformes and owls (Strigiformes in Europe and North America is extremely inconsistent. Our results, based on analyses of ITS-2 sequences suggest that the Cyathostoma (Hovorkonema nematodes found in the birds of prey and owls from Central Europe and North America probably belong to the same species, C. (Hovorkonema americana Chapin, 1925. We are convinced, that described in recent literature high ITS-2 divergence among C. (Hovorkonema nematodes collected from Europe, has occurred as a result of invalid synonimisation of some C. (Hovorkonema species. In our opinion C. (Hovorkonema americana (typically parasites of tracheae and air sacs of raptors and C. (Hovorkonema variegatum (Creplin, 1849 (typically parasites of tracheae of cranes and storks are valid molecular and morphologically distinct species.

A spatial theory for emergent multiple predator-prey interactions in food webs.

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Northfield, Tobin D; Barton, Brandon T; Schmitz, Oswald J

2017-09-01

Predator-prey interaction is inherently spatial because animals move through landscapes to search for and consume food resources and to avoid being consumed by other species. The spatial nature of species interactions necessitates integrating spatial processes into food web theory and evaluating how predators combine to impact their prey. Here, we present a spatial modeling approach that examines emergent multiple predator effects on prey within landscapes. The modeling is inspired by the habitat domain concept derived from empirical synthesis of spatial movement and interactions studies. Because these principles are motivated by synthesis of short-term experiments, it remains uncertain whether spatial contingency principles hold in dynamical systems. We address this uncertainty by formulating dynamical systems models, guided by core habitat domain principles, to examine long-term multiple predator-prey spatial dynamics. To describe habitat domains, we use classical niche concepts describing resource utilization distributions, and assume species interactions emerge from the degree of overlap between species. The analytical results generally align with those from empirical synthesis and present a theoretical framework capable of demonstrating multiple predator effects that does not depend on the small spatial or temporal scales typical of mesocosm experiments, and help bridge between empirical experiments and long-term dynamics in natural systems.

Bio-Physical Coupling of Seabirds and Prey with a Dynamic River Plume

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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

Predictive modelling of habitat selection by marine predators with respect to the abundance and depth distribution of pelagic prey.

Science.gov (United States)

Boyd, Charlotte; Castillo, Ramiro; Hunt, George L; Punt, André E; VanBlaricom, Glenn R; Weimerskirch, Henri; Bertrand, Sophie

2015-11-01

Understanding the ecological processes that underpin species distribution patterns is a fundamental goal in spatial ecology. However, developing predictive models of habitat use is challenging for species that forage in marine environments, as both predators and prey are often highly mobile and difficult to monitor. Consequently, few studies have developed resource selection functions for marine predators based directly on the abundance and distribution of their prey. We analysed contemporaneous data on the diving locations of two seabird species, the shallow-diving Peruvian Booby (Sula variegata) and deeper diving Guanay Cormorant (Phalacrocorax bougainvilliorum), and the abundance and depth distribution of their main prey, Peruvian anchoveta (Engraulis ringens). Based on this unique data set, we developed resource selection functions to test the hypothesis that the probability of seabird diving behaviour at a given location is a function of the relative abundance of prey in the upper water column. For both species, we show that the probability of diving behaviour is mostly explained by the distribution of prey at shallow depths. While the probability of diving behaviour increases sharply with prey abundance at relatively low levels of abundance, support for including abundance in addition to the depth distribution of prey is weak, suggesting that prey abundance was not a major factor determining the location of diving behaviour during the study period. The study thus highlights the importance of the depth distribution of prey for two species of seabird with different diving capabilities. The results complement previous research that points towards the importance of oceanographic processes that enhance the accessibility of prey to seabirds. The implications are that locations where prey is predictably found at accessible depths may be more important for surface foragers, such as seabirds, than locations where prey is predictably abundant. Analysis of the relative

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.

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.

Mr-Moose: An advanced SED-fitting tool for heterogeneous multi-wavelength datasets

Science.gov (United States)

Drouart, G.; Falkendal, T.

2018-04-01

We present the public release of Mr-Moose, a fitting procedure that is able to perform multi-wavelength and multi-object spectral energy distribution (SED) fitting in a Bayesian framework. This procedure is able to handle a large variety of cases, from an isolated source to blended multi-component sources from an heterogeneous dataset (i.e. a range of observation sensitivities and spectral/spatial resolutions). Furthermore, Mr-Moose handles upper-limits during the fitting process in a continuous way allowing models to be gradually less probable as upper limits are approached. The aim is to propose a simple-to-use, yet highly-versatile fitting tool fro handling increasing source complexity when combining multi-wavelength datasets with fully customisable filter/model databases. The complete control of the user is one advantage, which avoids the traditional problems related to the "black box" effect, where parameter or model tunings are impossible and can lead to overfitting and/or over-interpretation of the results. Also, while a basic knowledge of Python and statistics is required, the code aims to be sufficiently user-friendly for non-experts. We demonstrate the procedure on three cases: two artificially-generated datasets and a previous result from the literature. In particular, the most complex case (inspired by a real source, combining Herschel, ALMA and VLA data) in the context of extragalactic SED fitting, makes Mr-Moose a particularly-attractive SED fitting tool when dealing with partially blended sources, without the need for data deconvolution.

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.

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.

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.

Scat-detection dogs survey low density moose in New York

Science.gov (United States)

Heidi Kretser; Michale Glennon; Alice Whitelaw; Aimee Hurt; Kristine Pilgrim; Michael Schwartz

2016-01-01

The difficulty of collecting occurrence and population dynamics data in mammalian populations of low density poses challenges for making informed management decisions. We assessed the use of scat-detection dogs to search for fecal pellets in a low density moose (Alces alces) population in the Adirondack Park in New York State, and the success rate of DNA...

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.

Metal concentrations in selected tissues and main prey species of the annulated sea snake (Hydrophis cyanocinctus) in the Hara Protected Area, northeastern coast of the Persian Gulf, Iran

International Nuclear Information System (INIS)

Rezaie-Atagholipour, Mohsen; Riyahi-Bakhtiari, Alireza; Sajjadi, Mirmasoud; Yap, Chee Kong; Ghaffari, Sanaz; Ebrahimi-Sirizi, Zohreh; Ghezellou, Parviz

2012-01-01

This study is the first detailed ecotoxicological study of the annulated sea snake, Hydrophis cyanocinctus. Concentrations of lead, cadmium, nickel and vanadium were evaluated in muscle, liver, kidney, skin and blood of the annulated sea snake (H. cyanocinctus) and in the whole bodies of its main prey species (Periophthalmus waltoni and Boleophthalmus dussumieri) in the Hara Protected Area, the Persian Gulf. The mean concentrations of lead and vanadium were highest in the kidney, which identified the kidney as a target organ for metals in sea snakes as it is in other reptilian groups. Mean concentrations of cadmium and nickel were highest in the liver and skin, respectively. Mean cadmium concentrations were significantly higher in the liver compared to prey species, which indicated that prey items may be a source of cadmium for the annulated sea snake in the study area. Data presented here may be considered as a baseline for further ecotoxicological studies in sea snakes.

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

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.

Diversity in thermal affinity among key piscivores buffers impacts of ocean warming on predator-prey interactions.

Science.gov (United States)

Selden, Rebecca L; Batt, Ryan D; Saba, Vincent S; Pinsky, Malin L

2018-01-01

Asymmetries in responses to climate change have the potential to alter important predator-prey interactions, in part by altering the location and size of spatial refugia for prey. We evaluated the effect of ocean warming on interactions between four important piscivores and four of their prey in the U.S. Northeast Shelf by examining species overlap under historical conditions (1968-2014) and with a doubling in CO 2 . Because both predator and prey shift their distributions in response to changing ocean conditions, the net impact of warming or cooling on predator-prey interactions was not determined a priori from the range extent of either predator or prey alone. For Atlantic cod, an historically dominant piscivore in the region, we found that both historical and future warming led to a decline in the proportion of prey species' range it occupied and caused a potential reduction in its ability to exert top-down control on these prey. In contrast, the potential for overlap of spiny dogfish with prey species was enhanced by warming, expanding their importance as predators in this system. In sum, the decline in the ecological role for cod that began with overfishing in this ecosystem will likely be exacerbated by warming, but this loss may be counteracted by the rise in dominance of other piscivores with contrasting thermal preferences. Functional diversity in thermal affinity within the piscivore guild may therefore buffer against the impact of warming on marine ecosystems, suggesting a novel mechanism by which diversity confers resilience. © 2017 John Wiley & Sons Ltd.

Element patterns in albatrosses and petrels: Influence of trophic position, foraging range, and prey type

International Nuclear Information System (INIS)

Anderson, O.R.J.; Phillips, R.A.; Shore, R.F.; McGill, R.A.R.; McDonald, R.A.; Bearhop, S.

2010-01-01

We investigated the concentrations of 22 essential and non-essential elements among a community of Procellariiformes (and their prey) to identify the extent to which trophic position and foraging range governed element accumulation. Stable isotope analysis (SIA) was used to characterise trophic (δ 15 N) and spatial patterns (δ 13 C) among species. Few consistent patterns were observed in element distributions among species and diet appeared to be highly influential in some instances. Arsenic levels in seabird red blood cells correlated with δ 15 N and δ 13 C, demonstrating the importance of trophic position and foraging range for arsenic distribution. Arsenic concentrations in prey varied significantly across taxa, and in the strength of association with δ 15 N values (trophic level). In most instances, element patterns in Procellariiformes showed the clearest separation among species, indicating that a combination of prey selection and other complex species-specific characteristics (e.g. moult patterns) were generally more important determining factors than trophic level per se. - Trophic position, foraging range, and prey type were found to influence element compositions and concentrations in Procellariiformes from South Georgia.

Toward a community ecology of landscapes: predicting multiple predator-prey interactions across geographic space.

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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

Enhanced invertebrate prey production following estuarine restoration supports foraging for multiple species of juvenile salmonids (Oncorhynchus spp.)

Science.gov (United States)

Woo, Isa; Davis, Melanie; Ellings, Christopher S.; Nakai, Glynnis; Takekawa, John Y.; De La Cruz, Susan

2018-01-01

Estuaries provide crucial foraging resources and nursery habitat for threatened populations of anadromous salmon. As such, there has been a global undertaking to restore habitat and tidal processes in modified estuaries. The foraging capacity of these ecosystems to support various species of out-migrating juvenile salmon can be quantified by monitoring benthic, terrestrial, and pelagic invertebrate prey communities. Here, we present notable trends in the availability of invertebrate prey at several sites within a restoring large river delta in Puget Sound, Washington, U.S.A. Three years after the system was returned to tidal influence, we observed substantial additions to amphipod, copepod, and cumacean abundances in newly accessible marsh channels (from 0 to roughly 5,000–75,000 individuals/m2). In the restoration area, terrestrial invertebrate colonization was dependent upon vegetative cover, with dipteran and hymenopteran biomass increasing 3-fold between 1 and 3 years post-restoration. While the overall biodiversity within the restoration area was lower than in the reference marsh, estimated biomass was comparable to or greater than that found within the other study sites. This additional prey biomass likely provided foraging benefits for juvenile Chinook, chum, and coho salmon. Primary physical drivers differed for benthic, terrestrial, and pelagic invertebrates, and these invertebrate communities are expected to respond differentially depending on organic matter exchange and vegetative colonization. Restoring estuaries may take decades to meet certain success criteria, but our study demonstrates rapid enhancements in foraging resources understood to be used for estuary-dependent wildlife.

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

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

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.

Assessment of Exposure to Chlorinated Organics through the Ingestion of Moose Meat for a Canadian First Nation Community

Directory of Open Access Journals (Sweden)

Claire McAuley

2016-11-01

Full Text Available Moose is an important traditional food for members of the Swan River First Nation (SRFN, located in northern Alberta, Canada. As industrial development is encroaching on First Nations’ traditional territories in northern Alberta, community members are growing increasingly concerned for the sustainability and safety of their traditional foods. The Alberta Special Waste Treatment Centre (ASWTC is an industrial incineration facility located in the core of SRFN’s traditional territory. An accidental release at the ASWTC in 1996 resulted in a significant discharge of polychlorinated biphenyls (PCBs to the environment. In addition to this accident, the ongoing operation of the ASWTC is linked to routine low-level emissions of PCBs, polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs. Since the 1996 release, levels of PCBs and PCDD/Fs have been measured in wild game tissues and the provincial government has issued consumption advisories. This study was undertaken to provide answers to the community regarding food safety and was designed to address concerns regarding PCB and PCDD/F concentrations in moose tissues. Samples of moose muscle (n=15, liver (n=13 and kidney (n=14 were collected as part of regular food harvesting activities of the SRFN in the summer and fall of 2015 and generously shared by the SRFN hunters and harvesters to allow for their inclusion into the study. A risk assessment approach was used to evaluate the potential risks to human health using hazard quotients (HQ. All HQs were below the benchmark level of 0.2 for a single pathway exposure. The results show that PCB and PCDD/F concentrations in moose tissues were low and comparable to those of meats available in Canadian supermarkets. Based on results from this study, community exposure to PCBs and PCDD/Fs from the consumption of moose tissue is low and consumption may continue at quantities documented in regional studies.

A shallow-diving seabird predator as an indicator of prey availability in southern California waters: A longitudinal study

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Horn, M. H.; Whitcombe, C. D.

2015-06-01

We tested the hypothesis that the Elegant Tern (Thalasseus elegans), a plunge-diving predator, is an indicator of changes in the prey community in southern California coastal waters. Shannon diversity (H‧) of the tern's diet determined from dropped fish collected variously at the three nesting sites for 18 years over a 21-year interval (1993-2013) showed no significant change in diet diversity. Based on a species-accumulation curve, total diet species represented about 70% of an extrapolated asymptotic richness. Abundance patterns of five prey species making up > 75% of prey numbers for all years were compared with abundance patterns of the same species in independent surveys obtained from zooplankton tows, bottom trawls and power-plant entrapments. Three of the five species - northern anchovy, kelp pipefish and California lizardfish - showed significant, positive correlations between diet and survey abundances. Even though the tern's diet has been dominated by anchovy and pipefish, its diet is still broad, with prey taxa representing > 75% of the 42 species groups making up the California shelf fish fauna. Altogether, our results support the hypothesis that the Elegant Tern, with its flexible diet, is a qualitative indicator, a sentinel, of changes in the prey communities in southern California coastal waters.

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.

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.

Utility of stable isotope analysis in studying foraging ecology of herbivores: Examples from moose and caribou

Science.gov (United States)

Ben-David, Merav; Shochat, Einav; Adams, Layne G.

2001-01-01

Recently, researchers emphasized that patterns of stable isotope ratios observed at the individual level are a result of an interaction between ecological, physiological, and biochemical processes. Isotopic models for herbivores provide additional complications because those mammals consume foods that have high variability in nitrogen concentrations. In addition, distribution of amino acids in plants may differ greatly from that required by a herbivore. At northern latitudes, where the growing season of vegetation is short, isotope ratios in herbivore tissues are expected to differ between seasons. Summer ratios likely reflect diet composition, whereas winter ratios would reflect diet and nutrient recycling by the animals. We tested this hypothesis using data collected from blood samples of caribou (Rangifer tarandus) and moose (Alces alces) in Denali National Park and Preserve, Alaska, USA. Stable isotope ratios of moose and caribou were significantly different from each other in late summer-autumn and winter. Also, late summer-autumn and winter ratios differed significantly between seasons in both species. Nonetheless, we were unable to evaluate whether differences in seasonal isotopic ratios were a result of diet selection or a response to nutrient recycling. We believe that additional studies on plant isotopic ratios as related to ecological factors in conjunction with investigations of diet selection by the herbivores will enhance our understanding of those interactions. Also, controlled studies investigating the relation between diet and physiological responses in herbivores will increase the utility of isotopic analysis in studying foraging ecology of herbivores.

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.

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

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.

Continuous Integration for Concurrent MOOSE Framework and Application Development on GitHub

Directory of Open Access Journals (Sweden)

Andrew E. Slaughter

2015-11-01

Full Text Available For the past several years, Idaho National Laboratory’s MOOSE framework team has employed modern software engineering techniques (continuous integration, joint application/framework source code repos- itories, automated regression testing, etc. in developing closed-source multiphysics simulation software (Gaston et al., 'Journal of Open Research Software' vol. 2, article e10, 2014. In March 2014, the MOOSE framework was released under an open source license on GitHub, significantly expanding and diversifying the pool of current active and potential future contributors on the project. Despite this recent growth, the same philosophy of concurrent framework and application development continues to guide the project’s development roadmap. Several specific practices, including techniques for managing multiple repositories, conducting automated regression testing, and implementing a cascading build process are discussed in this short paper. Special attention is given to describing the manner in which these practices naturally synergize with the GitHub API and GitHub-specific features such as issue tracking, Pull Requests, and project forks.

Environmental fluctuations restrict eco-evolutionary dynamics in predator-prey system.

Science.gov (United States)

Hiltunen, Teppo; Ayan, Gökçe B; Becks, Lutz

2015-06-07

Environmental fluctuations, species interactions and rapid evolution are all predicted to affect community structure and their temporal dynamics. Although the effects of the abiotic environment and prey evolution on ecological community dynamics have been studied separately, these factors can also have interactive effects. Here we used bacteria-ciliate microcosm experiments to test for eco-evolutionary dynamics in fluctuating environments. Specifically, we followed population dynamics and a prey defence trait over time when populations were exposed to regular changes of bottom-up or top-down stressors, or combinations of these. We found that the rate of evolution of a defence trait was significantly lower in fluctuating compared with stable environments, and that the defence trait evolved to lower levels when two environmental stressors changed recurrently. The latter suggests that top-down and bottom-up changes can have additive effects constraining evolutionary response within populations. The differences in evolutionary trajectories are explained by fluctuations in population sizes of the prey and the predator, which continuously alter the supply of mutations in the prey and strength of selection through predation. Thus, it may be necessary to adopt an eco-evolutionary perspective on studies concerning the evolution of traits mediating species interactions. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

The adaptation of generalist predators' diet in a multi-prey context: insights from new functional responses.

Science.gov (United States)

Baudrot, Virgile; Perasso, Antoine; Fritsch, Clémentine; Giraudoux, Patrick; Raoul, Francis

2016-07-01

The ability for a generalist consumer to adapt its foraging strategy (the multi-species functional response, MSFR) is a milestone in ecology as it contributes to the structure of food webs. The trophic interaction between a generalist predator, as the red fox or the barn owl, and its prey community, mainly composed of small mammals, has been empirically and theoretically widely studied. However, the extent to which these predators adapt their diet according to both multi-annual changes in multiple prey species availability (frequency dependence) and the variation of the total prey density (density dependence) is unexplored.We provide a new general model of MSFR disentangling changes in prey preference according to variation of prey frequency (switching) and of total prey density (we propose the new concept of "rank switching"). We apply these models to two large data sets of red fox and barn owl foraging. We show that both frequency-dependent and density-dependent switching are critical properties of these two systems, suggesting that barn owl and red fox have an accurate image of the prey community in terms of frequency and absolute density. Moreover, we show that negative switching, which can lead to prey instability, is a strong property of the two systems. © 2016 by the Ecological Society of America.

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.

Sediment-induced turbidity impairs foraging performance and prey choice of planktivorous coral reef fishes.

Science.gov (United States)

Johansen, J L; Jones, G P

2013-09-01

Sedimentation is a substantial threat to aquatic ecosystems and a primary cause of habitat degradation on near-shore coral reefs. Although numerous studies have demonstrated major impacts of sedimentation and turbidity on corals, virtually nothing is known of the sensitivity of reef fishes. Planktivorous fishes are an important trophic group that funnels pelagic energy sources into reef ecosystems. These fishes are visual predators whose foraging is likely to be impaired by turbidity, but the threshold for such effects and their magnitude are unknown. This study examined the effect of sediment-induced turbidity on foraging in four species of planktivorous damselfishes (Pomacentridae) of the Great Barrier Reef, including inshore and offshore species that potentially differ in tolerance for turbidity. An experimental flow tunnel was used to quantify their ability to catch mobile and immobile planktonic prey under different levels of turbidity and velocity in the range encountered on natural and disturbed reefs. Turbidity of just 4 NTU (nephelometric turbidity units) reduced average attack success by up to 56%, with higher effect sizes for species with offshore distributions. Only the inshore species (Neopomacentrus bankieri), which frequently encounters this turbidity on coastal reefs, could maintain high prey capture success. At elevated turbidity similar to that found on disturbed reefs (8 NTU), attack success was reduced in all species examined by up to 69%. These reductions in attack success led to a 21-24% decrease in foraging rates for all mid to outer-shelf species, in spite of increasing attack rates at high turbidity. Although effects of turbidity varied among species, it always depended heavily on prey mobility and ambient velocity. Attack success was up to 14 times lower on mobile prey, leaving species relatively incapable of foraging on anything but immobile prey at high turbidity. Effects of turbidity were particularly prominent at higher velocities, as

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

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.

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.

The effect of light intensity on prey detection behavior in two Lake Malawi cichlids, Aulonocara stuartgranti and Tramitichromis sp.

Science.gov (United States)

Schwalbe, Margot A B; Webb, Jacqueline F

2015-04-01

Two sand-dwelling cichlids from Lake Malawi (Aulonocara stuartgranti, Tramitichromis sp.) that feed on benthic invertebrates, but have different lateral line phenotypes, use lateral line and/or visual cues to detect prey under light versus dark conditions. The current study examined how ecologically relevant variation in light intensity [0-800 lux (lx)] influences detection of prey (mobile, immobile) in each species by analyzing six behavioral parameters. Both species fed at light intensities ≥1 lx and trends in behavior among light intensities were informative. However, prey type and/or time of day (but not light intensity) predicted all four parameters analyzed with generalized linear mixed models in A. stuartgranti, whereas the interaction of light intensity and time of day predicted three of these parameters in Tramitichromis sp. Data suggest that the critical light intensity is 1-12 lx for both species, that the integration of visual and lateral line input explains differences in detection of mobile and immobile prey and behavioral changes at the transition from 1 to 0 lx in A. stuartgranti, and that Tramitichromis sp. likely uses binocular vision to locate prey. Differences in the sensory biology of species that exploit similar prey will have important implications for the trophic ecology of African cichlid fishes.

Development and Evaluation of MOOSES games in Flash/Macromedia

OpenAIRE

Ekse, Magnus Førland

2010-01-01

Video games are very popular today and the electronic entertainment industry is in many areas equal to the more mature entertainment industries like film and music in terms of usage and revenues. The MOOSES (Multiplayer On One Screen Entertainment System) allows players to play on one big screen together with the use of their mobile phone as a game controller. The framework was designed for easy development of multiplayer games in Java and C++.Flash is a very popular technology on the Interne...

Richness, diversity, and similarity of arthropod prey consumed by a community of Hawaiian forest birds.

Science.gov (United States)

Banko, Paul C.; Peck, Robert W.; Brinck, Kevin W.; Leonard, David L.

2015-01-01

We evaluated the diet richness, diversity, and similarity of a community of seven endemic and two introduced passerine birds by analyzing the composition of arthropod prey in fecal samples collected during 1994–1998 at Hakalau Forest National Wildlife Refuge, Hawai‘i Island. Most prey fragments were identified to order, but we also distinguished among morpho-species of Lepidoptera based on the shape of larval (caterpillar) mandibles for higher resolution of this important prey type. Diets were compared among feeding specialists, generalists, and “intermediate” species and among introduced and three endangered Hawaiian honeycreeper (Fringillidae) species. Lepidoptera (moths), especially the larval (caterpillar) stage, comprised the greatest proportion of prey in samples of all bird species except for the introduced Japanese white-eye (Zosterops japonicus; JAWE). Araneae (spiders) was the most abundant order in JAWE samples and the second most abundant order for most other species. The two specialist honeycreepers ranked lowest in the richness and diversity of arthropod orders, but only the ‘akiapōlā‘au (Hemignathus munroi, AKIP) was significantly lower than the three generalist or intermediate honeycreeper species. The diversity of arthropod orders was significantly lower for the three endangered honeycreeper species compared to the two introduced species. No significant differences were observed among the five honeycreepers with respect to the arthropod orders they consumed. The use of arthropod orders taken by endangered honeycreepers and introduced species was significantly different in all paired comparisons except for JAWE and ‘ākepa (Loxops coccineus; AKEP). In terms of richness and diversity of caterpillar morpho-species in the diet, only the specialist, AKEP, was significantly lower than all three generalist and intermediate species. Both AKEP and AKIP consumed a significantly different diet of caterpillar morpho-species compared to at least

A feasibility study on the use of the MOOSE computational framework to simulate three-dimensional deformation of CANDU reactor fuel elements

Energy Technology Data Exchange (ETDEWEB)

Gamble, Kyle A., E-mail: Kyle.Gamble@inl.gov [Royal Military College of Canada, Chemistry and Chemical Engineering, 13 General Crerar Crescent, Kingston, Ontario, Canada K7K 7B4 (Canada); Williams, Anthony F., E-mail: Tony.Williams@cnl.ca [Canadian Nuclear Laboratories, Fuel and Fuel Channel Safety, 1 Plant Road, Chalk River, Ontario, Canada K0J 1J0 (Canada); Chan, Paul K., E-mail: Paul.Chan@rmc.ca [Royal Military College of Canada, Chemistry and Chemical Engineering, 13 General Crerar Crescent, Kingston, Ontario, Canada K7K 7B4 (Canada); Wowk, Diane, E-mail: Diane.Wowk@rmc.ca [Royal Military College of Canada, Mechanical and Aerospace Engineering, 13 General Crerar Crescent, Kingston, Ontario, Canada K7K 7B4 (Canada)

2015-11-15

Highlights: • This is the first demonstration of using the MOOSE framework for modeling CANDU fuel. • Glued and frictionless contact algorithms behave as expected for 2D and 3D cases. • MOOSE accepts and correctly interprets functions of arbitrary form. • 3D deformation calculations accurately compare against analytical solutions. • MOOSE is a viable simulation tool for modeling accident reactor conditions. - Abstract: Horizontally oriented fuel bundles, such as those in CANada Deuterium Uranium (CANDU) reactors present unique modeling challenges. After long irradiation times or during severe transients the fuel elements can laterally deform out of plane due to processes known as bow and sag. Bowing is a thermally driven process that causes the fuel elements to laterally deform when a temperature gradient develops across the diameter of the element. Sagging is a coupled mechanical and thermal process caused by deformation of the fuel pin due to creep mechanisms of the sheathing after long irradiation times and or high temperatures. These out-of-plane deformations can lead to reduced coolant flow and a reduction in coolability of the fuel bundle. In extreme cases element-to-element or element-to-pressure tube contact could occur leading to reduced coolant flow in the subchannels or pressure tube rupture leading to a loss of coolant accident. This paper evaluates the capability of the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework developed at the Idaho National Laboratory to model these deformation mechanisms. The material model capabilities of MOOSE and its ability to simulate contact are also investigated.

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.

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

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.

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

Tactile Experience Shapes Prey-Capture Behavior in Etruscan Shrews

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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.

Presence-only Species Distribution Modeling for King Mackerel (Scomberomorus cavalla) and its 31 Prey Species in the Gulf of Mexico

Science.gov (United States)

Cai, X.; Simons, J.; Carollo, C.; Sterba-Boatwright, B.; Sadovski, A.

2016-02-01

Ecosystem based fisheries management has been broadly recognized throughout the world as a way to achieve better conservation. Therefore, there is a strong need for mapping of multi-species interactions or spatial distributions. Species distribution models are widely applied since information regarding the presence of species is usually only available for limited locations due to the high cost of fisheries surveys. Instead of regular presence and absence records, a large proportion of the fisheries survey data have only presence records. This makes the modeling problem one of one-class classification (presence only), which is much more complex than the regular two-class classification (presence/absence). In this study, four different presence-only species distribution algorithms (Bioclim, Domain, Mahal and Maxent) were applied using 13 environmental parameters (e.g., depth, DO, bottom types) as predictors to model the distribution of king mackerel (Scomberomorus cavalla) and its 31 prey species in the Gulf of Mexico (a total of 13625 georeferenced presence records from OBIS and GBIF were used). Five-fold cross validations were applied for each of the 128 (4 algorithms × 32 species) models. Area under curve (AUC) and correlation coefficient (R) were used to evaluate the model performances. The AUC of the models based on these four algorithms were 0.83±0.14, 0.77±0.16, 0.94±0.06 and 0.94±0.06, respectively; while R for the models were 0.47±0.27, 0.43±0.24, 0.27±0.16 and 0.76±0.16, respectively. Post hoc with Tukey's test showed that AUC for the Maxent-based models were significantly (pMexico to help managers better manage related fisheries resources.

Species-specific accumulation of polybrominated diphenyl ether flame retardants in birds of prey from the Chesapeake Bay region, USA

Energy Technology Data Exchange (ETDEWEB)

Chen Da, E-mail: chen@vims.ed [Department of Environmental and Aquatic Animal Health, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062 (United States); Hale, Robert C. [Department of Environmental and Aquatic Animal Health, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062 (United States); Watts, Bryan D. [Center for Conservation Biology, College of William and Mary, Williamsburg, VA 23185 (United States); La Guardia, Mark J.; Harvey, Ellen [Department of Environmental and Aquatic Animal Health, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062 (United States); Mojica, Elizabeth K. [Center for Conservation Biology, College of William and Mary, Williamsburg, VA 23185 (United States)

2010-05-15

Compared to organochlorines, little is known about polybrominated diphenyl ether (PBDE) contamination of birds of prey breeding in the Chesapeake Bay, the largest estuary in the U.S. This study examined and compared PBDE contamination in eggs of osprey, double-crested cormorant, brown pelican and peregrine falcon from this area. Several legacy persistent organic pollutants such as PCBs and DDE were also investigated. The level of urbanization of the landscape appeared to influence the level of PBDE exposure. PBDE congener distribution patterns varied between piscivorous and terrestrial-feeding birds. This suggests individual congeners may be subject to differences in bioaccumulation, biomagnification or metabolism in the aquatic and terrestrial food webs. Biomagnification of PBDEs was studied in the Bay aquatic food chains for the first time. A biomagnification factor of 25.1 was estimated for SIGMAPBDEs for the fish - osprey egg food chain. Hazard quotients, applied as a preliminary evaluation, indicated that PBDEs may pose a moderate hazard to ospreys and peregrine falcons through impairment of reproductive performance. - Birds of prey breeding in the Chesapeake Bay (USA) exhibited species-specific PBDE accumulation patterns.

Species-specific accumulation of polybrominated diphenyl ether flame retardants in birds of prey from the Chesapeake Bay region, USA

International Nuclear Information System (INIS)

Chen Da; Hale, Robert C.; Watts, Bryan D.; La Guardia, Mark J.; Harvey, Ellen; Mojica, Elizabeth K.

2010-01-01

Compared to organochlorines, little is known about polybrominated diphenyl ether (PBDE) contamination of birds of prey breeding in the Chesapeake Bay, the largest estuary in the U.S. This study examined and compared PBDE contamination in eggs of osprey, double-crested cormorant, brown pelican and peregrine falcon from this area. Several legacy persistent organic pollutants such as PCBs and DDE were also investigated. The level of urbanization of the landscape appeared to influence the level of PBDE exposure. PBDE congener distribution patterns varied between piscivorous and terrestrial-feeding birds. This suggests individual congeners may be subject to differences in bioaccumulation, biomagnification or metabolism in the aquatic and terrestrial food webs. Biomagnification of PBDEs was studied in the Bay aquatic food chains for the first time. A biomagnification factor of 25.1 was estimated for ΣPBDEs for the fish - osprey egg food chain. Hazard quotients, applied as a preliminary evaluation, indicated that PBDEs may pose a moderate hazard to ospreys and peregrine falcons through impairment of reproductive performance. - Birds of prey breeding in the Chesapeake Bay (USA) exhibited species-specific PBDE accumulation patterns.

Maximal feeding with active prey-switching: A kill-the-winner functional response and its effect on global diversity and biogeography

Science.gov (United States)

Vallina, S. M.; Ward, B. A.; Dutkiewicz, S.; Follows, M. J.

2014-01-01

Predators' switching towards the most abundant prey is a mechanism that stabilizes population dynamics and helps overcome competitive exclusion of species in food webs. Current formulations of active prey-switching, however, display non-maximal feeding in which the predators' total ingestion decays exponentially with the number prey species (i.e. the diet breadth) even though the total prey biomass stays constant. We analyse three previously published multi-species functional responses which have either active switching or maximal feeding, but not both. We identify the cause of this apparent incompatibility and describe a kill-the-winner formulation that combines active switching with maximal feeding. Active switching is shown to be a community response in which some predators become prey-selective and the formulations with maximal or non-maximal feeding are implicitly assuming different food web configurations. Global simulations using a marine ecosystem model with 64 phytoplankton species belonging to 4 major functional groups show that the species richness and biogeography of phytoplankton are very sensitive to the choice of the functional response for grazing. The phytoplankton biogeography reflects the balance between the competitive abilities for nutrient uptake and the degree of apparent competition which occurs indirectly between species that share a common predator species. The phytoplankton diversity significantly increases when active switching is combined with maximal feeding through predator-mediated coexistence.

Absence of frequent herpesvirus transmission in a nonhuman primate predator-prey system in the wild.

Science.gov (United States)

Murthy, Sripriya; Couacy-Hymann, Emmanuel; Metzger, Sonja; Nowak, Kathrin; De Nys, Helene; Boesch, Christophe; Wittig, Roman; Jarvis, Michael A; Leendertz, Fabian H; Ehlers, Bernhard

2013-10-01

Emergence of viruses into the human population by transmission from nonhuman primates (NHPs) represents a serious potential threat to human health that is primarily associated with the increased bushmeat trade. Transmission of RNA viruses across primate species appears to be relatively frequent. In contrast, DNA viruses appear to be largely host specific, suggesting low transmission potential. Herein, we use a primate predator-prey system to study the risk of herpesvirus transmission between different primate species in the wild. The system was comprised of western chimpanzees (Pan troglodytes verus) and their primary (western red colobus, Piliocolobus badius badius) and secondary (black-and-white colobus, Colobus polykomos) prey monkey species. NHP species were frequently observed to be coinfected with multiple beta- and gammaherpesviruses (including new cytomegalo- and rhadinoviruses). However, despite frequent exposure of chimpanzees to blood, organs, and bones of their herpesvirus-infected monkey prey, there was no evidence for cross-species herpesvirus transmission. These findings suggest that interspecies transmission of NHP beta- and gammaherpesviruses is, at most, a rare event in the wild.

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.

78 FR 73559 - Moose-Wilson Corridor Comprehensive Management Plan, Environmental Impact Statement, Grand Teton...

Science.gov (United States)

2013-12-06

...-Wilson Corridor Comprehensive Management Plan, Environmental Impact Statement, Grand Teton National Park... is preparing a Comprehensive Management Plan and Environmental Impact Statement (EIS) for the Moose...; (2) distinguish the corridor's fundamental and other important resources and values; (3) clearly...

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.

Circulating fat-soluble vitamin concentrations and nutrient composition of aquatic prey eaten by American oystercatchers (Haematopus palliatus) in the southeastern United States

Science.gov (United States)

Carlson-Bremer, Daphne; Norton, Terry M.; Sanders, Felicia J.; Winn, Brad; Spinks, Mark D.; Glatt, Batsheva A.; Mazzaro, Lisa; Jodice, Patrick G.R.; Chen, Tai C.; Dierenfeld, Ellen S.

2014-01-01

The American oystercatcher (Haematopus palliatus palliatus) is currently listed as a species of high concern by the United States Shorebird Conservation Plan. Because nutritional status directly impacts overall health and reproduction of individuals and populations, adequate management of a wildlife population requires intimate knowledge of a species' diet and nutrient requirements. Fat-soluble vitamin concentrations in blood plasma obtained from American oystercatchers and proximate, vitamin, and mineral composition of various oystercatcher prey species were determined as baseline data to assess nutritional status and nutrient supply. Bird and prey species samples were collected from the Cape Romain region, South Carolina, USA, and the Altamaha River delta islands, Georgia, USA, where breeding populations appear relatively stable in recent years. Vitamin A levels in blood samples were higher than ranges reported as normal for domestic avian species, and vitamin D concentrations were lower than anticipated based on values observed in poultry. Vitamin E levels were within ranges previously reported for avian groups with broadly similar feeding niches such as herons, gulls, and terns (eg, aquatic/estuarine/marine). Prey species (oysters, mussels, clams, blood arks [Anadara ovalis], whelks [Busycon carica], false angel wings [Petricola pholadiformis]) were similar in water content to vertebrate prey, moderate to high in protein, and moderate to low in crude fat. Ash and macronutrient concentrations in prey species were high compared with requirements of carnivores or avian species. Prey items analyzed appear to meet nutritional requirements for oystercatchers, as estimated by extrapolation from domestic carnivores and poultry species; excesses, imbalances, and toxicities—particularly of minerals and fat-soluble vitamins—may warrant further investigation.

Monitoring of caesium-137 in food plants and muscle from moose, red deer and wild reindeer in 2010

International Nuclear Information System (INIS)

Veiberg, Vebjoern; Gaare, Eldar; Stokke, Sigbjoern; Solberg, Erling J.; Skuterud, Lavrans

2011-01-01

The monitoring of Cs-137 fall-out from the Chernobyl accident in 1986, started the same year. Several plants and wild reindeer in natural ecosystems in Nord-Rondane have been followed annually ever since. Four more wild reindeer ranges were included in 2001: Setesdal-Ryfylkeheiene, Hardangervidda, Nord-Ottadalen, Snoehetta and Nord-Rondane. From 2007 Forollhogna was also included. On fixed plots in Nord-Rondane and Snoehetta some of the reindeer forage plants, including both higher plants and fruticose lichens, have been sampled and analyzed annually since 1986. This was also done in 2010. In addition plants and lichens were sampled at five locations along an altitudinal gradient at Soendre Knutshoe, and at 7-8 locations along an east-west gradient from Kollaflata to Skarhoe in the Jora valley continuing along the Aursjoe to Torbudalen. All these locations were sampled annually between 1987-1990, but they have not been sampled since. In 2010 samples from red deer and moose was also collected from eight different regions located within the following counties: Oppland, Telemark, Vest-Agder, Rogaland, Sogn and Fjordane, Nord-Troendelag, Nordland and Troms. Red deer were sampled in four regions and moose in six. Both species were sampled in Oppland. In 2010 76, 49 and 61 samples were collected from wild reindeer, red deer and moose respectively. All measures of caesium levels were performed on dried samples. For the 596 samples of plants and lichen the results refer to caesium-levels in dried samples. For the meat samples, results refer to caesium-137 levels in raw meat. Due to large variation in measured levels of caesium within species and sampling area, we give median values instead of mean values.The highest caesium levels in wild reindeer were found in Snoehetta (1010 Bq/kg) and Nord-Rondane (2686 Bq/kg). The levels found in the other areas were considerably lower. The highest caesium levels in both red deer (Sel, 677 Bq/kg) and moose (Vaaga, 365 Bq/kg) were found

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).

Aspects of the winter predator--prey relationship between sauger and threadfin shad in Watts Bar Reservoir, Tennessee

International Nuclear Information System (INIS)

McGee, M.V.; Griffith, J.S.; McLean, R.B.

1978-01-01

This study sought to determine the impact of cold-induced mortality and impingement of threadfin shad (Dorsoma petenense) on the food consumption and prey selection of sauger (Stizostedion canadense), and to estimate the ability of sauger to digest meals consumed at low temperatures in winter. Prey selection of sauger was monitored from November 1976 through April 1977. Stomach contents of 536 sauger indicated threadfin provided the entire forage base for sauger through January. Food consumption of sauger was reduced and prey selection shifted to other species after January due to the combined effects of predation, impingement, and natural mortality of cold-stressed threadfin. Threadfin shad of a size available to most sauger were virtually eliminated by February. From February through April some sauger utilized alternate prey species. Laboratory digestion rate studies of sauger indicated digestion of force-fed meals of 4 to 7 g fathead minnows (Pimephales promelas) could proceed to 90 percent completion in 54 h at 5 C, 47 hr at 10 C, and 25 hr at 15 C. Conclusions of this study are: (1) that threadfin shad were the most abundant and vulnerable prey species available to and utilized by sauger during the late fall and winter months; (2) extensive mortalities of threadfin due to cold-stress increased sauger predation on four alternate prey species; (3) sauger continued feeding and digesting meals at temperatures between 5 and 15 C every 1 to 3 days; (4) sauger stored excess energy available from threadfin early in the winter as visceral fat which was available later when food consumption was reduced

Aspects of the winter predator--prey relationship between sauger and threadfin shad in Watts Bar Reservoir, Tennessee

Energy Technology Data Exchange (ETDEWEB)

McGee, M.V.; Griffith, J.S.; McLean, R.B.

1978-04-01

This study sought to determine the impact of cold-induced mortality and impingement of threadfin shad (Dorsoma petenense) on the food consumption and prey selection of sauger (Stizostedion canadense), and to estimate the ability of sauger to digest meals consumed at low temperatures in winter. Prey selection of sauger was monitored from November 1976 through April 1977. Stomach contents of 536 sauger indicated threadfin provided the entire forage base for sauger through January. Food consumption of sauger was reduced and prey selection shifted to other species after January due to the combined effects of predation, impingement, and natural mortality of cold-stressed threadfin. Threadfin shad of a size available to most sauger were virtually eliminated by February. From February through April some sauger utilized alternate prey species. Laboratory digestion rate studies of sauger indicated digestion of force-fed meals of 4 to 7 g fathead minnows (Pimephales promelas) could proceed to 90 percent completion in 54 h at 5 C, 47 hr at 10 C, and 25 hr at 15 C. Conclusions of this study are: (1) that threadfin shad were the most abundant and vulnerable prey species available to and utilized by sauger during the late fall and winter months; (2) extensive mortalities of threadfin due to cold-stress increased sauger predation on four alternate prey species; (3) sauger continued feeding and digesting meals at temperatures between 5 and 15 C every 1 to 3 days; (4) sauger stored excess energy available from threadfin early in the winter as visceral fat which was available later when food consumption was reduced.

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.

Lead concentration in meat from lead-killed moose and predicted human exposure using Monte Carlo simulation.

Science.gov (United States)

Lindboe, M; Henrichsen, E N; Høgåsen, H R; Bernhoft, A

2012-01-01

Lead-based hunting ammunitions are still common in most countries. On impact such ammunition releases fragments which are widely distributed within the carcass. In Norway, wild game is an important meat source for segments of the population and 95% of hunters use lead-based bullets. In this paper, we have investigated the lead content of ground meat from moose (Alces alces) intended for human consumption in Norway, and have predicted human exposure through this source. Fifty-two samples from different batches of ground meat from moose killed with lead-based bullets were randomly collected. The lead content was measured by atomic absorption spectroscopy. The lead intake from exposure to moose meat over time, depending on the frequency of intake and portion size, was predicted using Monte Carlo simulation. In 81% of the batches, lead levels were above the limit of quantification of 0.03 mg kg(-1), ranging up to 110 mg kg(-1). The mean lead concentration was 5.6 mg kg(-1), i.e. 56 times the European Commission limit for lead in meat. For consumers eating a moderate meat serving (2 g kg(-1) bw), a single serving would give a lead intake of 11 µg kg(-1) bw on average, with maximum of 220 µg kg(-1) bw. Using Monte Carlo simulation, the median (and 97.5th percentile) predicted weekly intake of lead from moose meat was 12 µg kg(-1) bw (27 µg kg(-1) bw) for one serving per week and 25 µg kg(-1) bw (45 µg kg(-1) bw) for two servings per week. The results indicate that the intake of meat from big game shot with lead-based bullets imposes a significant contribution to the total human lead exposure. The provisional tolerable weekly intake set by the World Health Organization (WHO) of 25 µg kg(-1) bw is likely to be exceeded in people eating moose meat on a regular basis. The European Food Safety Authority (EFSA) has recently concluded that adverse effects may be present at even lower exposure doses. Hence, even occasional consumption of big game meat with lead levels as

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...

Permanence for a class of periodic time-dependent predator-prey system with dispersal in a patchy-environment

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 two patches, in which both the prey and predator species can disperse between two patches. By utilizing analytic method, sufficient and realistic conditions on permanence and the existence of periodic solution are established. The theoretical results are confirmed by a special example and numerical simulations

Using Pop-II models to predict effects of wolf predation and hunter harvests on elk, mule deer, and moose on the northern range

Science.gov (United States)

Mack, John A.; Singer, Francis J.

1993-01-01

The effects of establishing a gray wolf (Canis lupus) population in Yellowstone National Park were predicted for three ungulate species—elk (Cervus elaphus), mule deer (Odocoileus hemionus), and moose (Alces alces)—using previously developed POP-II population models. We developed models for 78 and 100 wolves. For each wolf population, we ran scenarios using wolf predation rates of 9, 12, and 15 ungulates/wolf/year. With 78 wolves and the antlerless elk harvest reduced 27%, our modeled elk population estimated were 5-18% smaller than the model estimate without wolves. With 100 wolves and the antlerless elk harvest reduced 27%, our elk population estimated were 11-30% smaller than the population estimates without wolves. Wolf predation effects were greater on the modeled mule deer population than on elk. With 78 wolves and no antlerless deer harvest, we predicted the mule deer population could be 13-44% larger than without wolves. With 100 wolves and no antlerless deer harvest, the mule deer population was 0-36% larger than without wolves. After wolf recovery, our POP-II models suggested moose harvests would have to be reduced at least 50% to maintain moose numbers at the levels predicted when wolves were not present. Mule deer and moose population data are limited, and these wolf predation effects may be overestimated if population sizes or male-female ratios were underestimated in our population models. We recommend additional mule deer and moose population data be obtained.

New insights in insect prey choice by chimpanzees and gorillas in southeast Cameroon: the role of nutritional value.

Science.gov (United States)

Deblauwe, Isra; Janssens, Geert P J

2008-01-01

The insect diet of chimpanzees and gorillas living at the northern periphery of the Dja Biosphere Reserve in southeast Cameroon and its nutritional contribution is described. We analyzed fecal samples and recorded additional evidence of insectivory. A detailed prey species list is presented for both apes. We carried out nutritional analyses (macronutrients, macro- and micro-minerals) on 11 important and eight nonimportant, but accessible, ant and termite prey species, and estimated the average nutrient intake/day through insects. Although gorillas ate insects more frequently, the average prey biomass intake/day by chimpanzees was twice that by gorillas. The lack of tool-use by gorillas cannot be the main reason for the small overlap of important prey species. Both apes did not seem to consume ant prey for one or more specific nutrients. Also other factors, such as medicinal use, should be considered. Termites, on the other hand, seemed to be selected for particular nutrients. Gorilla intake of the important termite prey, Cubitermes and Thoracotermes, met with estimated iron requirements. Their potential role as antidiarrheal treatment is as yet unclear. Chimpanzee intake of the important termite prey, Macrotermes spp., met with estimated manganese requirements and the protein intake/day (mean: 2 g/d) reached significant values (>20 g/d). To fully understand the importance of nutritional contributions of insects to ape diets in Cameroon, the chemical composition and nutrient intake of fruit and foliage in their diets should be investigated. (c) 2007 Wiley-Liss, Inc.

Prey Acceptability and Preference of Oenopia conglobata (Coleoptera: Coccinellidae, a Candidate for Biological Control in Urban Green Areas

Directory of Open Access Journals (Sweden)

Belén Lumbierres

2018-01-01

Full Text Available Oenopia conglobata is one of the most common ladybird species in urban green areas of the Mediterranean region. We have obtained data about its prey acceptability and prey preferences. In a laboratory experiment, we investigated the acceptability of seven aphid and one psyllid species as prey for this coccinellid: the aphids Chaitophorus populeti, Aphis gossypii, Aphis craccivora Monelliopsis caryae, Eucallipterus tiliae, Aphis nerii (on white poplar, pomegranate, false acacia, black walnut, lime, and oleander, respectively, and the psyllid Acizzia jamatonica on Persian silk tree. These species are abundant in urban green areas in the Mediterranean region. In addition, we tested the acceptability of Rhopalosiphum padi on barley, an aphid species easily reared in the laboratory. We also tested preferences of the predator in cafeteria experiments with three aphid species and one aphid and the psyllid. Adults and larvae of the coccinellid accepted all of the preys offered, except A. nerii, with a clear preference for M. caryae. The predator also showed preference for M. caryae when it was offered in a cafeteria experiment with other aphid species or with the psyllid. The aphid R. padi obtained a good acceptability and could be used for rearing O. conglobata in the laboratory.

Resource partitioning between sympatric starfish from tropical unconsolidated substrate: Implications for coexistence and top-down control on benthic prey

Science.gov (United States)

Fernandez, Wellington S.; Dias, Gustavo M.; Majer, Alessandra P.; Delboni, Cynthia G.; Denadai, Marcia R.; Turra, Alexander

2017-09-01

Starfish are important predators that may shape rocky shore communities, but their ecological role in unconsolidated substrate communities is still poorly known. We assessed the feeding niche overlap of two sympatric starfish, Astropecten marginatus and Luidia senegalensis, from the shallow subtidal zone in southeastern Brazil. During one year, we conducted monthly samples to compare diet composition, abundance and frequency of occurrence of each food item between species. With 24 of the 34 food items identified in this study consumed by both species, they exhibited generalist behaviors, with a more diverse diet during the warm periods, when the main prey items were abundant. However, A. marginatus showed more variation in abundance of prey consumed over time than L. senegalensis. The diet of A. marginatus consisted primarily of the bivalve Tivela mactroides and L. senegalensis of the bivalve Mulinia cleryana. The size of T. mactroides was positively correlated to the size of A. marginatus, while only small-sized individuals of L. senegalensis consumed this item, the most abundant prey in the area and an important food resource for local the community. The large quantity and variety of items consumed by both species support the structuring role of starfish in subtidal unconsolidated substrate communities, exerting a generalist top-down control, primarily on dominant bivalve populations. Temporal variation in the availability of the main prey may change how selective are both species. The differences in prey composition between species and the ontogenetic differences in prey selectivity by L. senegalensis may attenuate interspecific competition, facilitating their coexistence.

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-.

Indirect Allee effect, bistability and chaotic oscillations in a predator-prey discrete model of logistic type

International Nuclear Information System (INIS)

Lopez-Ruiz, Ricardo; Fournier-Prunaret, Daniele

2005-01-01

A cubic discrete coupled logistic equation is proposed to model the predator-prey problem. The coupling depends on the population size of both species and on a positive constant λ, which could depend on the prey reproduction rate and on the predator hunting strategy. Different dynamical regimes are obtained when λ is modified. For small λ, the species become extinct. For a bigger λ, the preys survive but the predators extinguish. Only when the prey population reaches a critical value then predators can coexist with preys. For increasing λ, a bistable regime appears where the populations apart of being stabilized in fixed quantities can present periodic, quasiperiodic and chaotic oscillations. Finally, bistability is lost and the system settles down in a steady state, or, for the biggest permitted λ, in an invariant curve. We also present the basins for the different regimes. The use of the critical curves lets us determine the influence of the zones with different number of first rank preimages in the bifurcation mechanisms of those basins

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.

Local extinction of a coral reef fish explained by inflexible prey choice

Science.gov (United States)

Brooker, R. M.; Munday, P. L.; Brandl, S. J.; Jones, G. P.

2014-12-01

While global extinctions of marine species are infrequent, local extinctions are becoming common. However, the role of habitat degradation and resource specialisation in explaining local extinction is unknown. On coral reefs, coral bleaching is an increasingly frequent cause of coral mortality that can result in dramatic changes to coral community composition. Coral-associated fishes are often specialised on a limited suite of coral species and are therefore sensitive to these changes. This study documents the local extinction of a corallivorous reef fish, Oxymonacanthus longirostris, following a mass bleaching event that altered the species composition of associated coral communities. Local extinction only occurred on reefs that also completely lost a key prey species, Acropora millepora, even though coral cover remained high. In an experimental test, fish continued to select bleached A. millepora over the healthy, but less-preferred prey species that resisted bleaching. These results suggest that behavioural inflexibility may limit the ability of specialists to cope with even subtle changes to resource availability.

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…

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.

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...

Functional responses and scaling in predator-prey interactions of marine fishes: contemporary issues and emerging concepts.

Science.gov (United States)

Hunsicker, Mary E; Ciannelli, Lorenzo; Bailey, Kevin M; Buckel, Jeffrey A; Wilson White, J; Link, Jason S; Essington, Timothy E; Gaichas, Sarah; Anderson, Todd W; Brodeur, Richard D; Chan, Kung-Sik; Chen, Kun; Englund, Göran; Frank, Kenneth T; Freitas, Vânia; Hixon, Mark A; Hurst, Thomas; Johnson, Darren W; Kitchell, James F; Reese, Doug; Rose, George A; Sjodin, Henrik; Sydeman, William J; van der Veer, Henk W; Vollset, Knut; Zador, Stephani

2011-12-01

Predator-prey interactions are a primary structuring force vital to the resilience of marine communities and sustainability of the world's oceans. Human influences on marine ecosystems mediate changes in species interactions. This generality is evinced by the cascading effects of overharvesting top predators on the structure and function of marine ecosystems. It follows that ecological forecasting, ecosystem management, and marine spatial planning require a better understanding of food web relationships. Characterising and scaling predator-prey interactions for use in tactical and strategic tools (i.e. multi-species management and ecosystem models) are paramount in this effort. Here, we explore what issues are involved and must be considered to advance the use of predator-prey theory in the context of marine fisheries science. We address pertinent contemporary ecological issues including (1) the approaches and complexities of evaluating predator responses in marine systems; (2) the 'scaling up' of predator-prey interactions to the population, community, and ecosystem level; (3) the role of predator-prey theory in contemporary fisheries and ecosystem modelling approaches; and (4) directions for the future. Our intent is to point out needed research directions that will improve our understanding of predator-prey interactions in the context of the sustainable marine fisheries and ecosystem management. 2011 Blackwell Publishing Ltd/CNRS.

Seasonal diet and prey preference of the African lion in a waterhole-driven semi-arid savanna.

Directory of Open Access Journals (Sweden)

Zeke Davidson

Full Text Available Large carnivores inhabiting ecosystems with heterogeneously distributed environmental resources with strong seasonal variations frequently employ opportunistic foraging strategies, often typified by seasonal switches in diet. In semi-arid ecosystems, herbivore distribution is generally more homogeneous in the wet season, when surface water is abundant, than in the dry season when only permanent sources remain. Here, we investigate the seasonal contribution of the different herbivore species, prey preference and distribution of kills (i.e. feeding locations of African lions in Hwange National Park, Zimbabwe, a semi-arid African savanna structured by artificial waterholes. We used data from 245 kills and 74 faecal samples. Buffalo consistently emerged as the most frequently utilised prey in all seasons by both male (56% and female (33% lions, contributing the most to lion dietary biomass. Jacobs' index also revealed that buffalo was the most intensively selected species throughout the year. For female lions, kudu and to a lesser extent the group "medium Bovidae" are the most important secondary prey. This study revealed seasonal patterns in secondary prey consumption by female lions partly based on prey ecology with browsers, such as giraffe and kudu, mainly consumed in the early dry season, and grazers, such as zebra and suids, contributing more to female diet in the late dry season. Further, it revealed the opportunistic hunting behaviour of lions for prey as diverse as elephants and mice, with elephants taken mostly as juveniles at the end of the dry season during droughts. Jacobs' index finally revealed a very strong preference for kills within 2 km from a waterhole for all prey species, except small antelopes, in all seasons. This suggested that surface-water resources form passive traps and contribute to the structuring of lion foraging behaviour.

Seasonal diet and prey preference of the African lion in a waterhole-driven semi-arid savanna.

Science.gov (United States)

Davidson, Zeke; Valeix, Marion; Van Kesteren, Freya; Loveridge, Andrew J; Hunt, Jane E; Murindagomo, Felix; Macdonald, David W

2013-01-01

Large carnivores inhabiting ecosystems with heterogeneously distributed environmental resources with strong seasonal variations frequently employ opportunistic foraging strategies, often typified by seasonal switches in diet. In semi-arid ecosystems, herbivore distribution is generally more homogeneous in the wet season, when surface water is abundant, than in the dry season when only permanent sources remain. Here, we investigate the seasonal contribution of the different herbivore species, prey preference and distribution of kills (i.e. feeding locations) of African lions in Hwange National Park, Zimbabwe, a semi-arid African savanna structured by artificial waterholes. We used data from 245 kills and 74 faecal samples. Buffalo consistently emerged as the most frequently utilised prey in all seasons by both male (56%) and female (33%) lions, contributing the most to lion dietary biomass. Jacobs' index also revealed that buffalo was the most intensively selected species throughout the year. For female lions, kudu and to a lesser extent the group "medium Bovidae" are the most important secondary prey. This study revealed seasonal patterns in secondary prey consumption by female lions partly based on prey ecology with browsers, such as giraffe and kudu, mainly consumed in the early dry season, and grazers, such as zebra and suids, contributing more to female diet in the late dry season. Further, it revealed the opportunistic hunting behaviour of lions for prey as diverse as elephants and mice, with elephants taken mostly as juveniles at the end of the dry season during droughts. Jacobs' index finally revealed a very strong preference for kills within 2 km from a waterhole for all prey species, except small antelopes, in all seasons. This suggested that surface-water resources form passive traps and contribute to the structuring of lion foraging behaviour.

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.

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

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.

Who's for dinner? High-throughput sequencing reveals bat dietary differentiation in a biodiversity hotspot where prey taxonomy is largely undescribed.

Science.gov (United States)

Burgar, Joanna M; Murray, Daithi C; Craig, Michael D; Haile, James; Houston, Jayne; Stokes, Vicki; Bunce, Michael

2014-08-01

Effective management and conservation of biodiversity requires understanding of predator-prey relationships to ensure the continued existence of both predator and prey populations. Gathering dietary data from predatory species, such as insectivorous bats, often presents logistical challenges, further exacerbated in biodiversity hot spots because prey items are highly speciose, yet their taxonomy is largely undescribed. We used high-throughput sequencing (HTS) and bioinformatic analyses to phylogenetically group DNA sequences into molecular operational taxonomic units (MOTUs) to examine predator-prey dynamics of three sympatric insectivorous bat species in the biodiversity hotspot of south-western Australia. We could only assign between 4% and 20% of MOTUs to known genera or species, depending on the method used, underscoring the importance of examining dietary diversity irrespective of taxonomic knowledge in areas lacking a comprehensive genetic reference database. MOTU analysis confirmed that resource partitioning occurred, with dietary divergence positively related to the ecomorphological divergence of the three bat species. We predicted that bat species' diets would converge during times of high energetic requirements, that is, the maternity season for females and the mating season for males. There was an interactive effect of season on female, but not male, bat species' diets, although small sample sizes may have limited our findings. Contrary to our predictions, females of two ecomorphologically similar species showed dietary convergence during the mating season rather than the maternity season. HTS-based approaches can help elucidate complex predator-prey relationships in highly speciose regions, which should facilitate the conservation of biodiversity in genetically uncharacterized areas, such as biodiversity hotspots. © 2013 John Wiley & Sons Ltd.

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.

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...

Habitat selection by a focal predator (Canis lupus) in a multiprey ecosystem of the northern Rockies

Science.gov (United States)

Milakovic, B.; Parker, K.L.; Gustine, D.D.; Lay, R.J.; Walker, A.B.D.; Gillingham, M.P.

2011-01-01

Large predators respond to land cover and physiography that maximize the likelihood of encountering prey. Using locations from global positioning system-collared wolves (Canis lupus), we examined whether land cover, vegetation productivity or change, or habitat-selection value for ungulate prey species themselves most influenced patterns of selection by wolves in a large, intact multiprey system of northern British Columbia. Selection models based on land cover, in combination with topographical features, consistently outperformed models based on indexes of vegetation quantity and quality (using normalized difference vegetation index) or on selection value to prey species (moose [Alces americanus], elk [Cervus elaphus], woodland caribou [Rangifer tarandus], and Stone's sheep [Ovis dalli stonei]). Wolves generally selected for shrub communities and high diversity of cover across seasons and avoided conifer stands and non-vegetated areas and west aspects year-round. Seasonal selection strategies were not always reflected in use patterns, which showed highest frequency of use in riparian, shrub, and conifer classes. Patterns of use and selection for individual wolf packs did not always conform to global models, and appeared related to the distribution of land cover and terrain within respective home ranges. Our findings corroborate the biological linkages between wolves and their habitat related to ease of movement and potential prey associations. ?? American 2011 Society of Mammalogists.

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.

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

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.

Water velocity influences prey detection and capture by drift-feeding juvenile coho salmon (Oncorhynchus kisutch) and steelhead (Oncorhynchus mykiss irideus)

Science.gov (United States)

John J. Piccolo; Nicholas F. Hughes; Mason D. Bryant

2008-01-01

We examined the effects of water velocity on prey detection and capture by drift-feeding juvenile coho salmon (Oncorhynchus kisutch) and steelhead (sea-run rainbow trout,Oncorhynchus mykiss irideus) in laboratory experiments. We used repeated-measures analysis of variance to test the effects of velocity, species, and the velocity x species interaction on prey capture...

Relationships of body lengths with mouth opening and prey length of nemipterid fishes (Regan, 1913 in the Gulf of Thailand

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Mithun Paul

2017-12-01

Full Text Available This study aims to investigate the relationship among total length (TL of fish with mouth opening namely horizontal opening (MH, vertical opening (VH, mouth area (MA and fork length (FL of seven sympatric nemipterid fish species and to know the relationship between total length and consumed prey length of five sympatric species sampled from the Gulf of Thailand in 2015. A total 883 fish were investigated collected from both cruise surveys and fishing port survey. TL was linearly and log-linearly related with both MV and MH for three and four species, respectively. MA’s were always the log linear relation of TL and shapes were nearly oval for all species. FL in all TL-FL relationships were proportional to the TL’s in all species (r2 = 0.94, P  .5 and in invertebrate prey items for N. tambuloides (P > .5. So, this study clearly confirms that nemipterid fishes of different sizes feed on all different specific prey items according to its own body size and feed according to size class for prey items available nearby.

"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…

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.

Residue levels of polychlorobiphenyls,. sigma. DDT, and mercury in bird species commonly preyed upon by the peregrine falcon (Falco peregrinus Tunst. ) in Sweden

Energy Technology Data Exchange (ETDEWEB)

Lindberg, P.; Odsjoe, T.; Reutergardh, L.

1985-03-01

The levels of polychlorobiphenyls (PCBs), ..sigma..DDT, and total mercury were analyzed in samples of common prey species of the peregrine falcon in two falcon territories, one in northern and one in southern Sweden. Resident and herbivorous prey species showed low residue levels, while elevated levels were found in birds feeding on animals in aquatic habitats. According to biomass, waders accounted for most of the mercury and ..sigma..DDT in the diet of the northern falcons, while the black-headed gulls had this role in southern Sweden. During the breeding season, the peregrines in northern Sweden were exposed to significantly higher levels of ..sigma..DDT and Hg than the southern peregrines. The estimated average residue levels (based on breast muscles) in a diet were in northern Sweden 0.26 ppm ..sigma..DDT, 0.47 ppm PCB and 0.20 ppm Hg wet-weight. Corresponding figures for southern Sweden were 0.17 ppm ..sigma..DDT, 0.53 ppm PCB and 0.07 ppm Hg. The organochlorine levels in a sample of peregrine eggs were higher than expected from contaminant levels in the diet. It is possible that the main accumulation of pesticides occurs on wintering grounds in western Europe for the Fennoscandian peregrines.

Decline of heterozygosity in a large but isolated population: a 45-year examination of moose genetic diversity on Isle Royale

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Renae L. Sattler

2017-07-01

Full Text Available Wildlife conservation and management approaches typically focus on demographic measurements to assess population viability over both short and long periods. However, genetic diversity is an important predictor of long term population vitality. We investigated the pattern of change in genetic diversity in a large and likely isolated moose (Alces alces population on Isle Royale (Lake Superior from 1960–2005. We characterized samples, partitioned into five different 5-year periods, using nine microsatellite loci and a portion of the mtDNA control region. We also simulated the moose population to generate a theoretical backdrop of genetic diversity change. In the empirical data, we found that the number of alleles was consistently low and that observed heterozygosity notably declined from 1960 to 2005 (p = 0.08, R2 = 0.70. Furthermore, inbreeding coefficients approximately doubled from 0.08 in 1960–65 to 0.16 in 2000–05. Finally, we found that the empirical rate of observed heterozygosity decline was faster than the rate of observed heterozygosity loss in our simulations. Combined, these data suggest that genetic drift and inbreeding occurred in the Isle Royale moose populations over the study period, leading to significant losses in heterozygosity. Although inbreeding can be mitigated by migration, we found no evidence to support the occurrence of recent migrants into the population using analysis of our mtDNA haplotypes nor microsatellite data. Therefore, the Isle Royale moose population illustrates that even large populations are subjected to inbreeding in the absence of migration.

Does small mammal prey guild affect the exposure of predators to anticoagulant rodenticides?

International Nuclear Information System (INIS)

Tosh, D.G.; McDonald, R.A.; Bearhop, S.; Lllewellyn, N.R.; Fee, S.; Sharp, E.A.; Barnett, E.A.; Shore, R.F.

2011-01-01

Ireland has a restricted small mammal prey guild but still includes species most likely to consume anticoagulant rodenticide (AR) baits. This may enhance secondary exposure of predators to ARs. We compared liver AR residues in foxes (Vulpes vulpes) in Northern Ireland (NI) with those in foxes from Great Britain which has a more diverse prey guild but similar agricultural use of ARs. Liver ARs were detected in 84% of NI foxes, more than in a comparable sample of foxes from Scotland and similar to that of suspected AR poisoned animals from England and Wales. High exposure in NI foxes is probably due to greater predation of commensal rodents and non-target species most likely to take AR baits, and may also partly reflect greater exposure to highly persistent brodifacoum and flocoumafen. High exposure is likely to enhance risk and Ireland may be a sentinel for potential effects on predator populations. - Highlights: → Exposure of a predator to anticoagulant rodenticides was compared in Britain and Ireland. → Exposure was higher in Ireland. → Differences driven by small mammal prey guilds. → Ireland a potential sentinel for predator exposure to anticoagulants. - Restriction of the small mammal prey guild is associated with enhanced exposure of predators to anticoagulant rodenticides.

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...

Predators and resources influence phosphorus transfer along an invertebrate food web through changes in prey behaviour.

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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

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.

An objective approach to determining the weight ranges of prey preferred by and accessible to the five large African carnivores.

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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

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.

Predictive modelling of habitat use by marine predators with respect to the abundance and depth distribution of pelagic prey

Science.gov (United States)

Boyd, Charlotte; Castillo, Ramiro; Hunt, George L.; Punt, André E..; VanBlaricom, Glenn R.; Weimerskirch, Henri; Bertrand, Sophie

2015-01-01

Understanding the ecological processes that underpin species distribution patterns is a fundamental goal in spatial ecology. However, developing predictive models of habitat use is challenging for species that forage in marine environments, as both predators and prey are often highly mobile and difficult to monitor. Consequently, few studies have developed resource selection functions for marine predators based directly on the abundance and distribution of their prey.

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.

David and Goliath: potent venom of an ant-eating spider (Araneae) enables capture of a giant prey

Science.gov (United States)

Pekár, Stano; Šedo, Onřej; Líznarová, Eva; Korenko, Stanislav; Zdráhal, Zdeněk

2014-07-01

It is rare to find a true predator that repeatedly and routinely kills prey larger than itself. A solitary specialised ant-eating spider of the genus Zodarion can capture a relatively giant prey. We studied the trophic niche of this spider species and investigated its adaptations (behavioural and venomic) that are used to capture ants. We found that the spider captures mainly polymorphic Messor arenarius ants. Adult female spiders captured large morphs while tiny juveniles captured smaller morphs, yet in both cases ants were giant in comparison with spider size. All specimens used an effective prey capture strategy that protected them from ant retaliation. Juvenile and adult spiders were able to paralyse their prey using a single bite. The venom glands of adults were more than 50 times larger than those of juvenile spiders, but the paralysis latency of juveniles was 1.5 times longer. This suggests that this spider species possesses very potent venom already at the juvenile stage. Comparison of the venom composition between juvenile and adult spiders did not reveal significant differences. We discovered here that specialised capture combined with very effective venom enables the capture of giant prey.

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

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

Evolution of predator dispersal in relation to spatio-temporal prey dynamics: how not to get stuck in the wrong place!

Directory of Open Access Journals (Sweden)

Justin M J Travis

Full Text Available The eco-evolutionary dynamics of dispersal are recognised as key in determining the responses of populations to environmental changes. Here, by developing a novel modelling approach, we show that predators are likely to have evolved to emigrate more often and become more selective over their destination patch when their prey species exhibit spatio-temporally complex dynamics. We additionally demonstrate that the cost of dispersal can vary substantially across space and time. Perhaps as a consequence of current environmental change, many key prey species are currently exhibiting major shifts in their spatio-temporal dynamics. By exploring similar shifts in silico, we predict that predator populations will be most vulnerable when prey dynamics shift from stable to complex. The more sophisticated dispersal rules, and greater variance therein, that evolve under complex dynamics will enable persistence across a broader range of prey dynamics than the rules which evolve under relatively stable prey conditions.

African vultures don't follow migratory herds: scavenger habitat use is not mediated by prey abundance.

Directory of Open Access Journals (Sweden)

Corinne J Kendall

Full Text Available The ongoing global decline in vulture populations raises major conservation concerns, but little is known about the factors that mediate scavenger habitat use, in particular the importance of abundance of live prey versus prey mortality. We test this using data from the Serengeti-Mara ecosystem in East Africa. The two hypotheses that prey abundance or prey mortality are the main drivers of vulture habitat use provide alternative predictions. If vultures select areas based only on prey abundance, we expect tracked vultures to remain close to herds of migratory wildebeest regardless of season. However, if vultures select areas where mortality rates are greatest then we expect vultures to select the driest regions, where animals are more likely to die of starvation, and to be attracted to migratory wildebeest only during the dry season when wildebeest mortality is greatest. We used data from GSM-GPS transmitters to assess the relationship between three vulture species and migratory wildebeest in the Mara-Serengeti ecosystem. Results indicate that vultures preferentially cluster around migratory herds only during the dry season, when herds experience their highest mortality. Additionally during the wet season, Ruppell's and Lappet-faced vultures select relatively dry areas, based on Normalized Difference Vegetation Index, whereas White-backed vultures preferred wetter areas during the wet season. Differences in habitat use among species may mediate coexistence in this scavenger guild. In general, our results suggest that prey abundance is not the primary driver of avian scavenger habitat use. The apparent reliance of vultures on non-migratory ungulates during the wet season has important conservation implications for vultures in light of on-going declines in non-migratory ungulate species and use of poisons in unprotected areas.

PRELIMINARY COUPLING OF THE MONTE CARLO CODE OPENMC AND THE MULTIPHYSICS OBJECT-ORIENTED SIMULATION ENVIRONMENT (MOOSE) FOR ANALYZING DOPPLER FEEDBACK IN MONTE CARLO SIMULATIONS

Energy Technology Data Exchange (ETDEWEB)

Matthew Ellis; Derek Gaston; Benoit Forget; Kord Smith

2011-07-01

In recent years the use of Monte Carlo methods for modeling reactors has become feasible due to the increasing availability of massively parallel computer systems. One of the primary challenges yet to be fully resolved, however, is the efficient and accurate inclusion of multiphysics feedback in Monte Carlo simulations. The research in this paper presents a preliminary coupling of the open source Monte Carlo code OpenMC with the open source Multiphysics Object-Oriented Simulation Environment (MOOSE). The coupling of OpenMC and MOOSE will be used to investigate efficient and accurate numerical methods needed to include multiphysics feedback in Monte Carlo codes. An investigation into the sensitivity of Doppler feedback to fuel temperature approximations using a two dimensional 17x17 PWR fuel assembly is presented in this paper. The results show a functioning multiphysics coupling between OpenMC and MOOSE. The coupling utilizes Functional Expansion Tallies to accurately and efficiently transfer pin power distributions tallied in OpenMC to unstructured finite element meshes used in MOOSE. The two dimensional PWR fuel assembly case also demonstrates that for a simplified model the pin-by-pin doppler feedback can be adequately replicated by scaling a representative pin based on pin relative powers.

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)

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

Algal subsidies enhance invertebrate prey for threatened shorebirds: A novel conservation tool on ocean beaches?

Science.gov (United States)

Schlacher, Thomas A.; Hutton, Briony M.; Gilby, Ben L.; Porch, Nicholaus; Maguire, Grainne S.; Maslo, Brooke; Connolly, Rod M.; Olds, Andrew D.; Weston, Michael A.

2017-05-01

Birds breeding on ocean beaches are threatened globally, often requiring significant investments in species conservation and habitat management. Conservation actions typically encompass spatial and temporal threat reductions and protection of eggs and broods. Still, populations decline or recover only slowly, calling for fresh approaches in beach-bird conservation. Because energetic demands are critically high during the nesting and chick rearing phases, and chick survival is particularly low, supplementing prey to breeding birds and their offspring is theoretically attractive as a means to complement more traditional conservation measures. Prey for plovers and similar species on ocean beaches consists of invertebrates (e.g. small crustaceans, insects) many of which feed on stranded masses of plant material (e.g. kelp and seagrass) and use this 'wrack' as habitat. We added wrack to the upper beach where plovers nest and their chicks forage to test whether algal subsidies promote the abundance and diversity of their invertebrate prey. Adding wrack to the upper beach significantly increased the abundance and diversity of invertebrate prey items. At wrack subsidies greater than 50% of surface cover invertebrate assemblages became highly distinct compared with those that received smaller additions of wrack. Substantial (2-4 fold) increases in the abundance amphipods and isopods that are principal prey items for plovers drove these shifts. This proof-of-concept study demonstrates the feasibility of food provisioning for birds on ocean shores. Whilst novel, it is practicable, inexpensive and does not introduce further restrictions or man-made structures. Thus, it can meaningfully add to the broader arsenal of conservation tools for threatened species that are wholly reliant on sandy beaches as breeding and foraging habitats.

Feeding preference of adult females of ribbonfish Trichiurus lepturus through prey proximate-composition and caloric values

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Vanessa Trindade Bittar

Full Text Available In the present study we analysed the proximate-composition and caloric values of the preferred prey consumed by ribbonfish, Trichiurus lepturus L. 1758 (adult females, that are distributed in the inner continental shelf from northern Rio de Janeiro State, southeastern Brazil (~22ºS, assessing the potential of nutritional and energetic approach as a tool to understand the feeding selective pattern of this marine top carnivore. The preferred prey of this predator composed of fish co-specifics, Pellona harroweri, Chirocentrodon bleekerianus, Lycengraulis grossidens, Peprilus paru, squid Doryteuthis plei, and shrimp Xiphopenaeus kroyeri were collected from 2007 to 2010 for proximate-composition (water, protein, lipid, ash, and carbohydrate and caloric value analyses. The correspondence analysis showed that protein is the main component in the prey species (61.32% of variance explained, standing out from the other nutrients. Lipid has the highest percentage related to L. grossidens, ash to X. kroyeri and carbohydrate to D. plei. The strong correlations between protein and caloric value (positive and lipid and caloric value (negative indicated that T. lepturus is attending its energy demand through the prey protein content. This work elucidated the feeding preference of adult females of T. lepturus in relation to nutritional and caloric content of their preferred prey. The species showed food selectivity to prey that provide more energy per ingested biomass, so that the feeding events can maximize the predator's caloric gain, which is obtained by a protein-based diet.

Congenital toxoplasmosis presenting with fetal atrial flutter after maternal ingestion of infected moose meat.

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Colosimo, Sarah M; Montoya, Jose G; Westley, Benjamin P; Jacob, Jack; Isada, Nelson B

2013-09-01

Consumption of undercooked game meat during pregnancy is considered a risk factor for congenital toxoplasmosis, but cases definitively linking ingestion of infected meat to clinical disease are lacking. We report a confirmed case of congenital toxoplasmosis identified because of atrial flutter in the fetus and linked to maternal consumption of Toxoplasma gondii PCR-positive moose meat.

Making inference from wildlife collision data: inferring predator absence from prey strikes

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Peter Caley

2017-02-01

Full Text Available Wildlife collision data are ubiquitous, though challenging for making ecological inference due to typically irreducible uncertainty relating to the sampling process. We illustrate a new approach that is useful for generating inference from predator data arising from wildlife collisions. By simply conditioning on a second prey species sampled via the same collision process, and by using a biologically realistic numerical response functions, we can produce a coherent numerical response relationship between predator and prey. This relationship can then be used to make inference on the population size of the predator species, including the probability of extinction. The statistical conditioning enables us to account for unmeasured variation in factors influencing the runway strike incidence for individual airports and to enable valid comparisons. A practical application of the approach for testing hypotheses about the distribution and abundance of a predator species is illustrated using the hypothesized red fox incursion into Tasmania, Australia. We estimate that conditional on the numerical response between fox and lagomorph runway strikes on mainland Australia, the predictive probability of observing no runway strikes of foxes in Tasmania after observing 15 lagomorph strikes is 0.001. We conclude there is enough evidence to safely reject the null hypothesis that there is a widespread red fox population in Tasmania at a population density consistent with prey availability. The method is novel and has potential wider application.

Making inference from wildlife collision data: inferring predator absence from prey strikes.

Science.gov (United States)

Caley, Peter; Hosack, Geoffrey R; Barry, Simon C

2017-01-01

Wildlife collision data are ubiquitous, though challenging for making ecological inference due to typically irreducible uncertainty relating to the sampling process. We illustrate a new approach that is useful for generating inference from predator data arising from wildlife collisions. By simply conditioning on a second prey species sampled via the same collision process, and by using a biologically realistic numerical response functions, we can produce a coherent numerical response relationship between predator and prey. This relationship can then be used to make inference on the population size of the predator species, including the probability of extinction. The statistical conditioning enables us to account for unmeasured variation in factors influencing the runway strike incidence for individual airports and to enable valid comparisons. A practical application of the approach for testing hypotheses about the distribution and abundance of a predator species is illustrated using the hypothesized red fox incursion into Tasmania, Australia. We estimate that conditional on the numerical response between fox and lagomorph runway strikes on mainland Australia, the predictive probability of observing no runway strikes of foxes in Tasmania after observing 15 lagomorph strikes is 0.001. We conclude there is enough evidence to safely reject the null hypothesis that there is a widespread red fox population in Tasmania at a population density consistent with prey availability. The method is novel and has potential wider application.

Collective strategies and cyclic dominance in asymmetric predator-prey spatial games.

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Cazaubiel, Annette; Lütz, Alessandra F; Arenzon, Jeferson J

2017-10-07

Predators may attack isolated or grouped prey in a cooperative, collective way. Whether a gregarious behavior is advantageous to each species depends on several conditions and game theory is a useful tool to deal with such a problem. We here extend the Lett et al. (2004) to spatially distributed populations and compare the resulting behavior with their mean-field predictions for the coevolving densities of predator and prey strategies. Besides its richer behavior in the presence of spatial organization, we also show that the coexistence phase in which collective and individual strategies for each group are present is stable because of an effective, cyclic dominance mechanism similar to a well-studied generalization of the Rock-Paper-Scissors game with four species, a further example of how ubiquitous this coexistence mechanism is. Copyright © 2017 Elsevier Ltd. All rights reserved.

Functional biology of sympatric krill species

DEFF Research Database (Denmark)

Agersted, Mette Dalgaard; Nielsen, Torkel Gissel

2016-01-01

Here we compare the functional biology of the sympatric krill species, Meganyctiphanes norvegica and Thysanoessa inermis. For M. norvegica, we investigated functional responses on diatoms and copepods, together with prey size spectra on plankton ,400 mm and copepods in the size range 500–3220 mm....... For T. inermis, only prey size spectrum on plankton ,400 mm were investigated. The prey size ranges of both species include organisms ,400 mm, and they consequently graze on several trophic levels. However, T. inermis feed on cells ,10 mm equivalent spherical diameter (ESD), whereas M. norvegica only...

Stable oscillations of a predator-prey probabilistic cellular automaton: a mean-field approach

International Nuclear Information System (INIS)

Tome, Tania; Carvalho, Kelly C de

2007-01-01

We analyze a probabilistic cellular automaton describing the dynamics of coexistence of a predator-prey system. The individuals of each species are localized over the sites of a lattice and the local stochastic updating rules are inspired by the processes of the Lotka-Volterra model. Two levels of mean-field approximations are set up. The simple approximation is equivalent to an extended patch model, a simple metapopulation model with patches colonized by prey, patches colonized by predators and empty patches. This approximation is capable of describing the limited available space for species occupancy. The pair approximation is moreover able to describe two types of coexistence of prey and predators: one where population densities are constant in time and another displaying self-sustained time oscillations of the population densities. The oscillations are associated with limit cycles and arise through a Hopf bifurcation. They are stable against changes in the initial conditions and, in this sense, they differ from the Lotka-Volterra cycles which depend on initial conditions. In this respect, the present model is biologically more realistic than the Lotka-Volterra model

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.

Effects of an exotic prey species on a native specialist: example of the snail kite

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Cattau, Christopher E.; Martin, J.; Kitchens, Wiley M.

2010-01-01

Despite acknowledging that exotic species can exhibit tremendous influence over native populations, few case studies have clearly demonstrated the effects of exotic prey species on native predators. We examined the effects of the recently introduced island apple snail (Pomacea insularum) on the foraging behavior and energetics of the endangered snail kite (Rostrhamus sociabilis plumbeus) in Florida. We conducted time-activity budgets: (i) on kites foraging for native Florida apple snails (Pomacea paludosa) in major wetland units within the kites' range that had not been invaded by the exotic island apple snail and (ii) on kites foraging for exotic apple snails in Lake Tohopekaliga, the only major wetland utilized by the snail kite that had suffered a serious invasion of P. insularum. When foraging for P. insularum, snail kites dropped a greater proportion of snails, and they experienced increased handling times and decreased consumption rates; however, kites foraging for P. insularum also spent a smaller proportion of the day in flight. Estimates of net daily energy balances between kites feeding on P. insularum versus P. paludosa were comparable for adults, but juveniles experienced energetic deficiencies when feeding on the exotic snail. Due to this discrepancy, we hypothesize that wetlands invaded by P. insularum, such as Lake Tohopekaliga, may function as ecological traps for the snail kite in Florida by attracting breeding adults but simultaneously depressing juvenile survival. This study highlights the conservation implications and importance of elucidating the effects that exotic species have on native specialists, especially those that are endangered, because subtle influences on behavior may have significant population consequences.

Ospreys do not teach offspring how to kill prey at the nest.

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Howard, Megan; Hoppitt, Will

2017-08-01

There is strong evidence for teaching in only a handful of species, most of which are cooperative breeders, leading some researchers to suggest that teaching may be more likely to evolve in such species. Alternatively, this initial distribution could be an artefact of the popularity and tractability of cooperative breeders as behavioural study systems. Therefore, establishing or refuting this potential evolutionary link requires researchers to assess potential cases of teaching in more non-cooperatively breeding species. We tested for teaching in the osprey ( Pandion haliaetus ), a non-cooperatively-breeding bird anecdotally reported to teach hunting skills to their offspring. We tested whether parents brought back more live prey to the nest as their offspring got older, allowing the latter to practice killing prey in a manner analogous to the progressive teaching seen in meerkats. We found the opposite trend to that predicted by the teaching hypothesis, indicating that ospreys do not teach their young at the nest. © 2017 The Author(s).

Structuring of zooplankton and fish larvae assemblages in a freshwater-influenced Greenlandic fjord- influence from hydrography and prey availability

DEFF Research Database (Denmark)

Swalethorp, Rasmus; Malanski, Evandro; Munk, Peter

2015-01-01

The recent increase in temperature and freshwater runoff in the Arctic will influence the functioning of the plankton ecosystem and hence the life of the fish larvae residing in these areas. Here, we studied the strength of physical– biological linkages and the adaptability of individual larval...... of the individual larval fish species. Larvae were feeding on a variety of prey taxa and sizes; some larval species were generalists, while others were more specialized or fed on alternative prey taxa. Differences in feeding strategies might have the consequence that the species will be differently affected...

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.

Spatial distribution of lion kills determined by the water dependency of prey species

NARCIS (Netherlands)

Boer, de W.F.; Vis, M.J.P.; Knegt, de H.J.; Rowles, C.; Kohi, E.; Langevelde, van F.; Peel, M.J.S.; Pretorius, Y.; Skidmore, A.K.; Slotow, R.; Wieren, van S.E.; Prins, H.H.T.

2010-01-01

Predation risk from lions (Panthera leo) has been linked to habitat characteristics and availability and traits of prey. We separated the effects of vegetation density and the presence of drinking water by analyzing locations of lion kills in relation to rivers with dense vegetation, which offer

Jaguar interactions with pumas and prey at the northern edge of jaguars’ range

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Carmina E. Gutiérrez-González

2017-01-01

Full Text Available We present the first study that evaluates jaguar-puma interactions in the arid lands of northern Mexico, where jaguars have their northernmost breeding population and both predators are persecuted for livestock depredation. We tested whether jaguars are the dominant species in this unique ecosystem, where: (1 pumas outnumber jaguars, (2 pumas are better adapted to arid environments, and (3 jaguars and pumas are of similar size. We analyzed four years of data with two approaches; a two species conditional occupancy model and an activity patterns analysis. We used camera location and prey presence as covariates for jaguar and puma detection and presence probabilities. We also explored overlap in activities of predators and prey. Where both species were detected, peccary presence was positively correlated with both jaguar and puma presence, whereas in areas where jaguars were detected but pumas were not, deer presence explained the probability of jaguar presence. We found that both predators were more likely to co-occur together than to be found independently, and so we rejected the hypothesis that jaguars were the dominant species in our study area. Predators were mainly nocturnal and their activity patterns overlapped by 60%. Jaguar, as compared with puma, overlapped more with deer and calves; puma overlapped with calves more than with other prey, suggesting a preference. We believe exploring predator relationships at different scales may help elucidate mechanisms that regulate their coexistence.

The Effect of Digestive Capacity on the Intake Rate of Toxic and Non-Toxic Prey in an Ecological Context.

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Thomas Oudman

Full Text Available Digestive capacity often limits food intake rate in animals. Many species can flexibly adjust digestive organ mass, enabling them to increase intake rate in times of increased energy requirement and/or scarcity of high-quality prey. However, some prey species are defended by secondary compounds, thereby forcing a toxin limitation on the forager's intake rate, a constraint that potentially cannot be alleviated by enlarging digestive capacity. Hence, physiological flexibility may have a differential effect on intake of different prey types, and consequently on dietary preferences. We tested this effect in red knots (Calidris canutus canutus, medium-sized migratory shorebirds that feed on hard-shelled, usually mollusc, prey. Because they ingest their prey whole and crush the shell in their gizzard, the intake rate of red knots is generally constrained by digestive capacity. However, one of their main prey, the bivalve Loripes lucinalis, imposes a toxin constraint due to its symbiosis with sulphide-oxidizing bacteria. We manipulated gizzard sizes of red knots through prolonged exposure to hard-shelled or soft foods. We then measured maximum intake rates of toxic Loripes versus a non-toxic bivalve, Dosinia isocardia. We found that intake of Dosinia exponentially increased with gizzard mass, confirming earlier results with non-toxic prey, whereas intake of Loripes was independent of gizzard mass. Using linear programming, we show that this leads to markedly different expected diet preferences in red knots that try to maximize energy intake rate with a small versus a large gizzard. Intra- and inter-individual variation in digestive capacity is found in many animal species. Hence, the here proposed functional link with individual differences in foraging decisions may be general. We emphasize the potential relevance of individual variation in physiology when studying trophic interactions.

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

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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.

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

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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.

Predator-dependent functional response in wolves: from food limitation to surplus killing.

Science.gov (United States)

Zimmermann, Barbara; Sand, Håkan; Wabakken, Petter; Liberg, Olof; Andreassen, Harry Peter

2015-01-01

The functional response of a predator describes the change in per capita kill rate to changes in prey density. This response can be influenced by predator densities, giving a predator-dependent functional response. In social carnivores which defend a territory, kill rates also depend on the individual energetic requirements of group members and their contribution to the kill rate. This study aims to provide empirical data for the functional response of wolves Canis lupus to the highly managed moose Alces alces population in Scandinavia. We explored prey and predator dependence, and how the functional response relates to the energetic requirements of wolf packs. Winter kill rates of GPS-collared wolves and densities of cervids were estimated for a total of 22 study periods in 15 wolf territories. The adult wolves were identified as the individuals responsible for providing kills to the wolf pack, while pups could be described as inept hunters. The predator-dependent, asymptotic functional response models (i.e. Hassell-Varley type II and Crowley-Martin) performed best among a set of 23 competing linear, asymptotic and sigmoid models. Small wolf packs acquired >3 times as much moose biomass as required to sustain their field metabolic rate (FMR), even at relatively low moose abundances. Large packs (6-9 wolves) acquired less biomass than required in territories with low moose abundance. We suggest the surplus killing by small packs is a result of an optimal foraging strategy to consume only the most nutritious parts of easy accessible prey while avoiding the risk of being detected by humans. Food limitation may have a stabilizing effect on pack size in wolves, as supported by the observed negative relationship between body weight of pups and pack size. © 2014 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

Effects of intraguild predators on nest-site selection by prey.

Science.gov (United States)

Huang, Wen-San; Pike, David A

2012-01-01

Nest-site selection involves tradeoffs between the risk of predation (on females and/or nests) and nest-site quality (microenvironment), and consequently suitable nesting sites are often in limited supply. Interactions with "classical" predators (e.g., those not competing for shared resources) can strongly influence nest-site selection, but whether intraguild predation also influences this behavior is unknown. We tested whether risk of predation from an intraguild predator [the diurnal scincid lizard Eutropis (Mabuya) longicaudata] influences nest-site selection by its prey (the nocturnal gecko Gekko hokouensis) on Orchid Island, Taiwan. These two species putatively compete for shared resources, including invertebrate prey and nesting microhabitat, but the larger E. longicaudata also predates G. hokouensis (but not its hard-shelled eggs). Both species nested within a concrete wall containing a series of drainage holes that have either one ("closed-in") or two openings ("open"). In allopatry, E. longicaudata preferred to nest within holes that were plugged by debris (thereby protecting eggs from water intrusion), whereas G. hokouensis selected holes that were open at both ends (facilitating escape from predators). When we experimentally excluded E. longicaudata from its preferred nesting area, G. hokouensis not only nested in higher abundances, but also modified its nest-site selection, such that communal nesting was more prevalent and both open and closed-in holes were used equally. Egg viability was unaffected by the choice of hole type, but was reduced slightly (by 7%) in the predator exclusion area (presumably due to higher local incubation temperatures). Our field experiment demonstrates that intraguild predators can directly influence the nest density of prey by altering maternal nest-site selection behavior, even when the predator and prey are active at different times of day and the eggs are not at risk of predation.

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

To eat and not be eaten: modelling resources and safety in multi-species animal groups.

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Umesh Srinivasan

Full Text Available Using mixed-species bird flocks as an example, we model the payoffs for two types of species from participating in multi-species animal groups. Salliers feed on mobile prey, are good sentinels and do not affect prey capture rates of gleaners; gleaners feed on prey on substrates and can enhance the prey capture rate of salliers by flushing prey, but are poor sentinels. These functional types are known from various animal taxa that form multi-species associations. We model costs and benefits of joining groups for a wide range of group compositions under varying abundances of two types of prey-prey on substrates and mobile prey. Our model predicts that gleaners and salliers show a conflict of interest in multi-species groups, because gleaners benefit from increasing numbers of salliers in the group, whereas salliers benefit from increasing gleaner numbers. The model also predicts that the limits to size and variability in composition of multi-species groups are driven by the relative abundance of different types of prey, independent of predation pressure. Our model emphasises resources as a primary driver of temporal and spatial group dynamics, rather than reproductive activity or predation per se, which have hitherto been thought to explain patterns of multi-species group formation and cohesion. The qualitative predictions of the model are supported by empirical patterns from both terrestrial and marine multi-species groups, suggesting that similar mechanisms might underlie group dynamics in a range of taxa. The model also makes novel predictions about group dynamics that can be tested using variation across space and time.

Prey selection of corallivorous muricids at Koh Tao (Gulf of Thailand) four years after a major coral bleaching event

NARCIS (Netherlands)

Moerland, M.S.; Scott, C.M.; Hoeksema, B.W.

2016-01-01

Corallivorous Drupella (Muricidae) snails at Koh Tao are reported to have extended their range of prey species following a major coral bleaching event in 2010. Populations of their preferred Acropora prey had locally diminished in both size and abundance, and the snails had introduced free-living

Does the aggressiveness of the prey modify the attack behavior of the predator Supputius cincticeps (Stål (Hemiptera, Pentatomidae?

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Rafael Braga da Silva

2012-06-01

Full Text Available Does the aggressiveness of the prey modify the attack behavior of the predator Supputius cincticeps (Stål (Hemiptera, Pentatomidae? The stink bug Supputius cincticeps (Stål (Hemiptera, Pentatomidae is a predator found in several Brazilian regions, which possesses desirable attributes as a natural control agent and in biological control programs. The aim of this study was to test if the attack behavior and predation success of S. cincticeps were affected by prey species. Larvae of Tenebrio molitor (L. (Coleoptera, Tenebrionidae, Spodoptera frugiperda (J. E. Smith (Lepidoptera, Noctuidae, and Thyrinteina arnobia (Stoll (Lepidoptera, Geometridae were offered to S. cincticeps in laboratory bioassays where predatory attack and prey defensive behaviors were observed for 2-hour periods. The attack behavior of S. cincticeps changed with the prey species offered. More than 25% of T. molitor and S. frugiperda larvae were immediately attacked, but T. arnobia was not immediately attacked by S. cincticeps. Successful attack (i.e., successful insertion of the predator stylets into the prey depends on the region of the body attacked, with a greater proportion of successful attacks in the anterior than in the median or posterior regions. Larvae of T. arnobia and S. frugiperda displayed a sequence of abrupt head and body movements in response to S. cincticeps attack. Attempts of predation were more successful on T. molitor and S. frugiperda than on T. arnobia. Information about the differential attack behavior of S. cincticeps on different prey species is important for designing successful biological control programs using this hemipteran predator.

Predicting predatory impact of juvenile invasive lionfish (Pterois volitans) on a crustacean prey using functional response analysis: effects of temperature, habitat complexity and light regimes

KAUST Repository

South, Josie

2017-07-01

The ecological implications of biotic interactions, such as predator-prey relationships, are often context-dependent. Comparative functional responses analysis can be used under different abiotic contexts to improve understanding and prediction of the ecological impact of invasive species. Pterois volitans (Lionfish) [Linnaeus 1758] is an established invasive species in the Caribbean and Gulf of Mexico, with a more recent invasion into the Mediterranean. Lionfish are generalist predators that impact a wide range of commercial and non-commercial species. Functional response analysis was employed to quantify interaction strength between lionfish and a generic prey species, the shrimp (Paleomonetes varians) [Leach 1814], under the contexts of differing temperature, habitat complexity and light wavelength. Lionfish have prey population destabilising Type II functional responses under all contexts examined. Significantly more prey were consumed at 26 °C than at 22 °C. Habitat complexity did not significantly alter the functional response parameters. Significantly more prey were consumed under white light and blue light than under red light. Attack rate was significantly higher under white light than under blue or red light. Light wavelength did not significantly change handling times. The impacts on prey populations through feeding rates may increase with concomitant temperature increase. As attack rates are very high at low habitat complexity this may elucidate the cause of high impact upon degraded reef ecosystems with low-density prey populations, although there was little protection conferred through habitat complexity. Only red light (i.e. dark) afforded any reduction in predation pressure. Management initiatives should account for these environmental factors when planning mitigation and prevention strategies.

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

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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.

Population and prey of the Bengal Tiger Panthera tigris tigris (Linnaeus, 1758 (Carnivora: Felidae in the Sundarbans, Bangladesh

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M.M.H. Khan

2012-02-01

Full Text Available The results from intensive small scale surveys are often difficult to extrapolate to wider spatial scales, yet an understanding at such scales is critical for assessing the minimum densities and populations of rare and wide ranging species. In this paper, the minimum size of population and minimum density estimates of Bengal Tigers Panthera tigris tigris and its prey were conducted from 2005 to 2007 using camera traps for 90 days and using distance sampling surveys for over 200 days, respectively. The results were extrapolated from the core study area in Katka-Kochikhali, southeastern Sundarbans, to five additional sites using indices of abundance. With the use of 10 camera-traps at 15 trap-points, field data provided a total of 829 photos, including seven photos of five individual tigers. A total of 5.0 (SE = 0.98 tigers (adults and sub-adults are thus estimated in the core area with an estimated density of 4.8 tigers/100km2. Distance sampling surveys conducted on large mammalian prey species obtained an overall density estimate of 27.9 individuals/km2 and a biomass density of 1,037kg/km2. Indices of abundance were obtained by using tiger track sighting rates (number of tracks/km of riverbank and the sighting rates of the prey species (number of prey/km of riverbank in the core area and in five additional sites across the region. The densities of tiger tracks and sighting rates of prey were strongly correlated suggesting a wide scale relationship between predator and prey in the region. By combining the estimates of absolute density with indices of abundance, an average of 3.7 tigers/100km2 across the region is estimated, which given an area of 5,770km2, predicts a minimum of approximately 200 tigers in the Bangladesh Sundarbans.

Insectivorous birds eavesdrop on the pheromones of their prey.

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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.

The interplay among prey preference, nutrient enrichment and stability in an omnivory system

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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.

The king of snakes: performance and morphology of intraguild predators (Lampropeltis) and their prey (Pantherophis).

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Penning, David A; Moon, Brad R

2017-03-15

Across ecosystems and trophic levels, predators are usually larger than their prey, and when trophic morphology converges, predators typically avoid predation on intraguild competitors unless the prey is notably smaller in size. However, a currently unexplained exception occurs in kingsnakes in the genus Lampropeltis Kingsnakes are able to capture, constrict and consume other snakes that are not only larger than themselves but that are also powerful constrictors (such as ratsnakes in the genus Pantherophis ). Their mechanisms of success as intraguild predators on other constrictors remain unknown. To begin addressing these mechanisms, we studied the scaling of muscle cross-sectional area, pulling force and constriction pressure across the ontogeny of six species of snakes ( Lampropeltis californiae , L. getula , L. holbrooki , Pantherophis alleghaniensis , P. guttatus and P. obsoletus ). Muscle cross-sectional area is an indicator of potential force production, pulling force is an indicator of escape performance, and constriction pressure is a measure of prey-handling performance. Muscle cross-sectional area scaled similarly for all snakes, and there was no significant difference in maximum pulling force among species. However, kingsnakes exerted significantly higher pressures on their prey than ratsnakes. The similar escape performance among species indicates that kingsnakes win in predatory encounters because of their superior constriction performance, not because ratsnakes have inferior escape performance. The superior constriction performance by kingsnakes results from their consistent and distinctive coil posture and perhaps from additional aspects of muscle structure and function that need to be tested in future research. © 2017. Published by The Company of Biologists Ltd.

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...

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

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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

Do top predators cue on sound production by mesopelagic prey?

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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?

Prey transport kinematics in Tupinambis teguixin and Varanus exanthematicus: conservation of feeding behavior in 'chemosensory-tongued' lizards.

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Elias, J A; McBrayer, L D; Reilly, S M

2000-02-01

Although lizards have been predicted to show extensive intraoral prey-processing behaviors, quantitative analyses of the types of prey-processing behavior they demonstrate and of their kinematics have been limited. The more basal lizard lineages (Iguanians) have undergone some study, but the prey-processing repertoires of crown taxa have not been thoroughly examined and quantitative comparisons of behaviors within or among species have not been made. In this study, the prey transport behavior of the savannah monitor (Varanus exanthematicus) and gold tegu (Tupinambis teguixin) are described. Although these two lineages have independently evolved tongues that are highly specialized for chemoreception, we found that they share the same three distinct types of transport behavior. These behavior patterns are (i) a purely inertial transport, (ii) an inertial transport with use of the tongue, and (iii) a non-inertial lingual transport. The tongue is used extensively in both the inertial and the purely lingual transport behaviors. More than 75 % of all transport behaviors involved tongue movements. These species appear to exhibit a conservation of feeding kinematics compared with patterns known for basal lizards. A hypothesis for the evolution of inertial feeding is proposed.

Factors mediating co-occurrence of an economically valuable introduced fish and its native frog prey.

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Hartman, Rosemary; Pope, Karen; Lawler, Sharon

2014-06-01

Habitat characteristics mediate predator-prey coexistence in many ecological systems but are seldom considered in species introductions. When economically important introduced predators are stocked despite known negative impacts on native species, understanding the role of refuges, landscape configurations, and community interactions can inform habitat management plans. We measured these factors in basins with introduced trout (Salmonidae) and the Cascades frog (Rana cascadae) to determine, which are responsible for observed patterns of co-occurrence of this economically important predator and its native prey. Large, vegetated shallows were strongly correlated to co-occurrence, and R. cascadae larvae occur in shallower water when fish are present, presumably to escape predation. The number of nearby breeding sites of R. cascadae was also correlated to co-occurrence, but only when the western toad (Anaxyrus boreas) was present. Because A. boreas larvae are unpalatable to fish and resemble R. cascadae, they may provide protection from trout via Batesian mimicry. Although rescue-effect dispersal from nearby populations may maintain co-occurrence, within-lake factors proved more important for predicting co-occurrence. Learning which factors allow co-occurrence between economically important introduced species and their native prey enables managers to make better-informed stocking decisions. © 2013 Society for Conservation Biology.

Ninety-nine de novo assembled genomes from the moose (Alces alces) rumen microbiome provide new insights into microbial plant biomass degradation

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Svartström, Olov; Alneberg, Johannes; Terrapon, Nicolas; Lombard, Vincent; de Bruijn, Ino; Malmsten, Jonas; Dalin, Ann-Marie; Muller, Emilie E.L.; Shah, Pranjul; Wilmes, Paul; Henrissat, Bernard; Aspeborg, Henrik; Andersson, Anders F.

2017-01-01

The moose (Alces alces) is a ruminant that harvests energy from fiber-rich lignocellulose material through carbohydrate-active enzymes (CAZymes) produced by its rumen microbes. We applied shotgun metagenomics to rumen contents from six moose to obtain insights into this microbiome. Following binning, 99 metagenome-assembled genomes (MAGs) belonging to eleven prokaryotic phyla were reconstructed and characterized based on phylogeny and CAZyme profile. The taxonomy of these MAGs reflected the overall composition of the metagenome, with dominance of the phyla Bacteroidetes and Firmicutes. Unlike in other ruminants, Spirochaetes constituted a significant proportion of the community and our analyses indicate that the corresponding strains are primarily pectin digesters. Pectin-degrading genes were also common in MAGs of Ruminococcus, Fibrobacteres and Bacteroidetes, and were overall overrepresented in the moose microbiome compared to other ruminants. Phylogenomic analyses revealed several clades within the Bacteriodetes without previously characterized genomes. Several of these MAGs encoded a large numbers of dockerins, a module usually associated with cellulosomes. The Bacteroidetes dockerins were often linked to CAZymes and sometimes encoded inside polysaccharide utilization loci (PULs), which has never been reported before. The almost one hundred CAZyme-annotated genomes reconstructed in this study provides an in-depth view of an efficient lignocellulose-degrading microbiome and prospects for developing enzyme technology for biorefineries. PMID:28731473

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

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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.

Spatial match-mismatch between juvenile fish and prey provides a mechanism for recruitment variability across contrasting climate conditions in the eastern Bering Sea.

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Siddon, Elizabeth Calvert; Kristiansen, Trond; Mueter, Franz J; Holsman, Kirstin K; Heintz, Ron A; Farley, Edward V

2013-01-01

Understanding mechanisms behind variability in early life survival of marine fishes through modeling efforts can improve predictive capabilities for recruitment success under changing climate conditions. Walleye pollock (Theragra chalcogramma) support the largest single-species commercial fishery in the United States and represent an ecologically important component of the Bering Sea ecosystem. Variability in walleye pollock growth and survival is structured in part by climate-driven bottom-up control of zooplankton composition. We used two modeling approaches, informed by observations, to understand the roles of prey quality, prey composition, and water temperature on juvenile walleye pollock growth: (1) a bioenergetics model that included local predator and prey energy densities, and (2) an individual-based model that included a mechanistic feeding component dependent on larval development and behavior, local prey densities and size, and physical oceanographic conditions. Prey composition in late-summer shifted from predominantly smaller copepod species in the warmer 2005 season to larger species in the cooler 2010 season, reflecting differences in zooplankton composition between years. In 2010, the main prey of juvenile walleye pollock were more abundant, had greater biomass, and higher mean energy density, resulting in better growth conditions. Moreover, spatial patterns in prey composition and water temperature lead to areas of enhanced growth, or growth 'hot spots', for juvenile walleye pollock and survival may be enhanced when fish overlap with these areas. This study provides evidence that a spatial mismatch between juvenile walleye pollock and growth 'hot spots' in 2005 contributed to poor recruitment while a higher degree of overlap in 2010 resulted in improved recruitment. Our results indicate that climate-driven changes in prey quality and composition can impact growth of juvenile walleye pollock, potentially severely affecting recruitment variability.

Nest occupation and prey grabbing by saker falcon (Falco cherrug on power lines in the province of Vojvodina (Serbia

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Puzović S.

2008-01-01

Full Text Available Research on nest occupation and prey grabbing by saker falcon (Falco cherrug on power lines in Vojvodina (Serbia was done in the period from 1986 to 2004. During three specially analyzed periods, saker falcon took the nests of raven (Corvus corax in 91% of a total of 22 cases of nest occupation, and those of hooded crow (Corvus corone cornix in only 9%. Saker falcon regularly grabs prey from different birds that occasionally or constantly spend time around power lines [Kestrel (Falco tinnunculus, hobby (Falco subbuteo, hooded crow (Corvus corone cornix, jack-daw (Corvus monedula, marsh harrier (Circus aeruginosus, hen harrier (Circus cyaneus, buzzard (Buteo buteo, and raven (Corvus corax]. One year a studied pair of saker falcons on a power line in Donji Srem, Serbia grabbed prey from five different species of birds. Out of a total of 40 cases of prey grabbing in the period from January to December, as much 70% of the grabbed prey was taken from kestrel (Falco tinnunculus. During the winter and early spring, prey was grabbed predominantly by males; after May, prey was sometimes grabbed by females as well. Most of the grabbed prey was common vole (Microtus arvalis.

Effects of prey size and foraging mode on the ontogenetic change in feeding niche ofColostethus stepheni (Anura: Dendrobatidae).

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Lima, Albertina P; Moreira, Gloria

1993-03-01

The feeding niche ofColostethus stepheni changes during ontogeny. Small individuals eat small arthropods, principally mites and collembolans, and larger frogs eat bigger prey of other types. The shift in prey types is not a passive effect of selection for bigger prey. There is a strong relationship between electivity for prey types and frog size, independent of electivity for prey size. Four indices of general activity during foraging (number of movements, velocity, total area utilized and time spent moving), which are associated with electivity for prey types in adult frogs and lizards, did not predict the ontogenetic change in the diet ofC. stepheni. Apparently, the behavioral changes that cause the ontogenetic change inC. stepheni are more subtle than shifts in general activity during foraging. Studies of niche partitioning in communities of anurans that do not take into consideration ontogenetic changes in diet and seasonal changes in the size structures of populations present a partial and possibly erroneous picture of the potential interactions among species.

Monitoring an alien invasion: DNA barcoding and the identification of lionfish and their prey on coral reefs of the Mexican Caribbean.

Science.gov (United States)

Valdez-Moreno, Martha; Quintal-Lizama, Carolina; Gómez-Lozano, Ricardo; García-Rivas, María Del Carmen

2012-01-01

In the Mexican Caribbean, the exotic lionfish Pterois volitans has become a species of great concern because of their predatory habits and rapid expansion onto the Mesoamerican coral reef, the second largest continuous reef system in the world. This is the first report of DNA identification of stomach contents of lionfish using the barcode of life reference database (BOLD). We confirm with barcoding that only Pterois volitans is apparently present in the Mexican Caribbean. We analyzed the stomach contents of 157 specimens of P. volitans from various locations in the region. Based on DNA matches in the Barcode of Life Database (BOLD) and GenBank, we identified fishes from five orders, 14 families, 22 genera and 34 species in the stomach contents. The families with the most species represented were Gobiidae and Apogonidae. Some prey taxa are commercially important species. Seven species were new records for the Mexican Caribbean: Apogon mosavi, Coryphopterus venezuelae, C. thrix, C. tortugae, Lythrypnus minimus, Starksia langi and S. ocellata. DNA matches, as well as the presence of intact lionfish in the stomach contents, indicate some degree of cannibalism, a behavior confirmed in this species by the first time. We obtained 45 distinct crustacean prey sequences, from which only 20 taxa could be identified from the BOLD and GenBank databases. The matches were primarily to Decapoda but only a single taxon could be identified to the species level, Euphausia americana. This technique proved to be an efficient and useful method, especially since prey species could be identified from partially-digested remains. The primary limitation is the lack of comprehensive coverage of potential prey species in the region in the BOLD and GenBank databases, especially among invertebrates.

Monitoring an alien invasion: DNA barcoding and the identification of lionfish and their prey on coral reefs of the Mexican Caribbean.

Directory of Open Access Journals (Sweden)

Martha Valdez-Moreno

Full Text Available BACKGROUND: In the Mexican Caribbean, the exotic lionfish Pterois volitans has become a species of great concern because of their predatory habits and rapid expansion onto the Mesoamerican coral reef, the second largest continuous reef system in the world. This is the first report of DNA identification of stomach contents of lionfish using the barcode of life reference database (BOLD. METHODOLOGY/PRINCIPAL FINDINGS: We confirm with barcoding that only Pterois volitans is apparently present in the Mexican Caribbean. We analyzed the stomach contents of 157 specimens of P. volitans from various locations in the region. Based on DNA matches in the Barcode of Life Database (BOLD and GenBank, we identified fishes from five orders, 14 families, 22 genera and 34 species in the stomach contents. The families with the most species represented were Gobiidae and Apogonidae. Some prey taxa are commercially important species. Seven species were new records for the Mexican Caribbean: Apogon mosavi, Coryphopterus venezuelae, C. thrix, C. tortugae, Lythrypnus minimus, Starksia langi and S. ocellata. DNA matches, as well as the presence of intact lionfish in the stomach contents, indicate some degree of cannibalism, a behavior confirmed in this species by the first time. We obtained 45 distinct crustacean prey sequences, from which only 20 taxa could be identified from the BOLD and GenBank databases. The matches were primarily to Decapoda but only a single taxon could be identified to the species level, Euphausia americana. CONCLUSIONS/SIGNIFICANCE: This technique proved to be an efficient and useful method, especially since prey species could be identified from partially-digested remains. The primary limitation is the lack of comprehensive coverage of potential prey species in the region in the BOLD and GenBank databases, especially among invertebrates.

Monitoring an Alien Invasion: DNA Barcoding and the Identification of Lionfish and Their Prey on Coral Reefs of the Mexican Caribbean

Science.gov (United States)

Valdez-Moreno, Martha; Quintal-Lizama, Carolina; Gómez-Lozano, Ricardo; García-Rivas, María del Carmen

2012-01-01

Background In the Mexican Caribbean, the exotic lionfish Pterois volitans has become a species of great concern because of their predatory habits and rapid expansion onto the Mesoamerican coral reef, the second largest continuous reef system in the world. This is the first report of DNA identification of stomach contents of lionfish using the barcode of life reference database (BOLD). Methodology/Principal Findings We confirm with barcoding that only Pterois volitans is apparently present in the Mexican Caribbean. We analyzed the stomach contents of 157 specimens of P. volitans from various locations in the region. Based on DNA matches in the Barcode of Life Database (BOLD) and GenBank, we identified fishes from five orders, 14 families, 22 genera and 34 species in the stomach contents. The families with the most species represented were Gobiidae and Apogonidae. Some prey taxa are commercially important species. Seven species were new records for the Mexican Caribbean: Apogon mosavi, Coryphopterus venezuelae, C. thrix, C. tortugae, Lythrypnus minimus, Starksia langi and S. ocellata. DNA matches, as well as the presence of intact lionfish in the stomach contents, indicate some degree of cannibalism, a behavior confirmed in this species by the first time. We obtained 45 distinct crustacean prey sequences, from which only 20 taxa could be identified from the BOLD and GenBank databases. The matches were primarily to Decapoda but only a single taxon could be identified to the species level, Euphausia americana. Conclusions/Significance This technique proved to be an efficient and useful method, especially since prey species could be identified from partially-digested remains. The primary limitation is the lack of comprehensive coverage of potential prey species in the region in the BOLD and GenBank databases, especially among invertebrates. PMID:22675470

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.

Prey and Non-prey Arthropods Sharing a Host Plant: Effects on Induced Volatile Emission and Predator Attraction

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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

First experimental evidence that a harvestman (Arachnida: Opiliones detects odors of non-rotten dead prey by olfaction

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Thaiany Miranda Costa

2013-06-01

Full Text Available Harvestmen feed on live, dead and fresh, or decomposing animals, fungi, and plant matter, being very dependent on chemoreception to find food. Herein we performed an experiment to test if individuals of Discocyrtus pectinifemur Mello-Leitão, 1937 (Gonyleptidae (n = 23 behave differently when in contact with olfactory cues from different sources (rotten prey, non-rotten prey and a control. Using dead crickets in a box covered with a mesh, and recording the time the harvestmen spent in the vicinities of the box, we show that D. pectinifemur detects non-rotten prey and stays longer on it than on the other two treatments. Our results contrast with a previous study on another species, showing that we should not generalize results obtained for one species. Our data also suggest that olfactory receptors occur on the legs of these harvestmen and that D. pectinifemur might choose dietary items based on olfaction.

Bats as the main prey of wintering long-eared owl (Asio otus) in Beijing: Integrating biodiversity protection and urban management.

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Tian, Long; Zhou, Xuwei; Shi, Yang; Guo, Yumin; Bao, Weidong

2015-03-01

The loss of biodiversity from urbanized areas is a major environmental problem challenging policy-makers throughout the world. Solutions to this problem are urgently required in China. We carried out a case study of wintering long-eared owls (Asio otus) and their main prey to illustrate the negative effects of urbanization combined with ineffective conservation of biodiversity in Beijing. Field monitoring of owl numbers at two roosting sites from 2004 to 2012 showed that the owl population had fallen rapidly in metropolitan Beijing. Analysis of pellet contents identified only seven individuals of two species of shrew. The majority of mammalian prey comprised four bat and seven rodent species, making up 29.3% and 29.5% of the prey items, respectively. Prey composition varied significantly among years at the two sample sites. At the urban site the consumption of bats and rodents declined gradually over time, while predation on birds increased. In contrast, at the suburban site the prey composition showed an overall decrease in the number of bats, a sharp increase and a subsequent decrease in bird prey, and the number of rodent prey fell to a low point. Rapid development of real estate and inadequate greenfield management in city parks resulted in negative effects on the bird and small mammal habitat of urban areas in Beijing. We suggest that measures to conserve biodiversity should be integrated into future urban planning to maintain China's rich biodiversity while also achieving sustainable economic development. © 2014 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

How do brent geese (Branta b. bernicla) cope with evil?; complex relationships between predators and prey

NARCIS (Netherlands)

Ebbinge, B.S.; Spaans, B.

2002-01-01

Actual predation is rarely observed in the field, and therefore the role of predators is often severely underestimated. Species are limited in their distribution, which is caused not only by predation but also by the anti-predator behaviour that prey-species have developed under the continuous

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

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

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

Songbirds and Birds of Prey, Unit 6, Colorado Division of Wildlife.

Science.gov (United States)

Hooper, Jon K.; Smith, Dwight R.

This booklet on songbirds and birds of prey is part of a series developed to encourage youth to pursue environmental projects. The manual explains bird anatomy and physiology, bird watching, types of feeders and shelter, and bird identification. Descriptions of feeding, hunting, and nesting habits are given for many species of birds. Also,…

Species replacement by a nonnative salmonid alters ecosystem function by reducing prey subsidies that support riparian spiders

Science.gov (United States)

Benjamin, J.R.; Fausch, K.D.; Baxter, C.V.

2011-01-01

Replacement of a native species by a nonnative can have strong effects on ecosystem function, such as altering nutrient cycling or disturbance frequency. Replacements may cause shifts in ecosystem function because nonnatives establish at different biomass, or because they differ from native species in traits like foraging behavior. However, no studies have compared effects of wholesale replacement of a native by a nonnative species on subsidies that support consumers in adjacent habitats, nor quantified the magnitude of these effects. We examined whether streams invaded by nonnative brook trout (Salvelinus fontinalis) in two regions of the Rocky Mountains, USA, produced fewer emerging adult aquatic insects compared to paired streams with native cutthroat trout (Oncorhynchus clarkii), and whether riparian spiders that depend on these prey were less abundant along streams with lower total insect emergence. As predicted, emergence density was 36% lower from streams with the nonnative fish. Biomass of brook trout was higher than the cutthroat trout they replaced, but even after accounting for this difference, emergence was 24% lower from brook trout streams. More riparian spiders were counted along streams with greater total emergence across the water surface. Based on these results, we predicted that brook trout replacement would result in 6-20% fewer spiders in the two regions. When brook trout replace cutthroat trout, they reduce cross-habitat resource subsidies and alter ecosystem function in stream-riparian food webs, not only owing to increased biomass but also because traits apparently differ from native cutthroat trout. ?? 2011 Springer-Verlag.

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.

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

Morphological correlates of prey consumed by Podarcis melisellensis (Braun, 1877 and P. siculus (Rafinesque, 1810 (Sauria, Lacertidae from two mainland regions in the eastern Adriatic area

Directory of Open Access Journals (Sweden)

Stamenković S.Ž.

2013-01-01

Full Text Available The correlation between trophic utilization and morphology was studied for two lizard species (Podarcis melisellensis and P. siculus from two mainland localities in the eastern Adriatic area; this is the first report of trophic and morphometric data for P. melisellensis from mainland populations. Variance partitioning showed that most of the variation in morphological traits for the analyzed lizards was the result of differences between species, and to a lesser extent between sexes. Locality did not have a strong effect on the variation of morphological traits. Prey weight is the only characteristic of prey that generally exhibits correlations with morphological characteristics rather than prey size. The pattern of correlations is generally weaker for P. melisellensis than for P. siculus. Optimal foraging theory predictions were generally confirmed: P. siculus is more constrained by trophic resource availability, with a premium on larger and heavier prey consumed in the less productive locality (SM, which can be relaxed in more productive regions (KL. P. melisellensis shows such constraints only for males in the less productive region (SM. Females of both species consume heavier prey. [Projekat Ministarstva nauke Republike Srbije, br. III43001 i br. 173011

Errors associated with moose-hunter counts of occupied beaver Castor fiber lodges in Norway

OpenAIRE

Parker, Howard; Rosell, Frank; Gustavsen, Per Øyvind

2002-01-01

In Norway, Sweden and Finland moose Alces alces hunting teams are often employed to survey occupied beaver (Castor fiber and C. canadensis) lodges while hunting. Results may be used to estimate population density or trend, or for issuing harvest permits. Despite the method's increasing popularity, the errors involved have never been identified. In this study we 1) compare hunting-team counts of occupied lodges with total counts, 2) identify the sources of error between counts and 3) evaluate ...

Cost of living dictates what whales, dolphins and porpoises eat: the importance of prey quality on predator foraging strategies.

Directory of Open Access Journals (Sweden)

Jérôme Spitz

Full Text Available Understanding the mechanisms that drive prey selection is a major challenge in foraging ecology. Most studies of foraging strategies have focused on behavioural costs, and have generally failed to recognize that differences in the quality of prey may be as important to predators as the costs of acquisition. Here, we tested whether there is a relationship between the quality of diets (kJ · g(-1 consumed by cetaceans in the North Atlantic and their metabolic costs of living as estimated by indicators of muscle performance (mitochondrial density, n = 60, and lipid content, n = 37. We found that the cost of living of 11 cetacean species is tightly coupled with the quality of prey they consume. This relationship between diet quality and cost of living appears to be independent of phylogeny and body size, and runs counter to predictions that stem from the well-known scaling relationships between mass and metabolic rates. Our finding suggests that the quality of prey rather than the sheer quantity of food is a major determinant of foraging strategies employed by predators to meet their specific energy requirements. This predator-specific dependence on food quality appears to reflect the evolution of ecological strategies at a species level, and has implications for risk assessment associated with the consequences of changing the quality and quantities of prey available to top predators in marine ecosystems.

Assessment of prey overlap between a native (Polistes humilis) and an introduced (Vespula germanica) social wasp using morphology and phylogenetic analyses of 16S rDNA.

Science.gov (United States)

Kasper, Marta L; Reeson, Andrew F; Cooper, Steven J B; Perry, Kym D; Austin, Andrew D

2004-07-01

Abstract In newly invaded communities, interspecific competition is thought to play an important role in determining the success of the invader and its impact on the native community. In southern Australia, the native Polistes humilis was the predominant social wasp prior to the arrival of the exotic Vespula germanica (Hymenoptera: Vespidae). Both species forage for similar resources (water, pulp, carbohydrate and protein prey), and concerns have arisen about potential competition between them. The aim of this study was to identify the protein foods that these wasps feed on. As many prey items are masticated by these wasps to the degree that they cannot be identified using conventional means, morphological identification was complemented by sequencing fragments of the mitochondrial 16S rRNA gene. GenBank searches using blast and phylogenetic analyses were used to identify prey items to at least order level. The results were used to construct complete prey inventories for the two species. These indicate that while P. humilis is restricted to feeding on lepidopteran larvae, V. germanica collects a variety of prey of invertebrate and vertebrate origin. Calculated values of prey overlap between the two species are used to discuss the implications of V. germanica impacting on P. humilis. Results obtained are compared to those gained by solely 'conventional' methods, and the advantages of using DNA-based taxonomy in ecological studies are emphasized.

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...

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...

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...

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...

Diet and prey availability of terrestrial insectivorous birds prone to extinction in amazonian forest fragments

Directory of Open Access Journals (Sweden)

Luiz Augusto Macedo Mestre

2010-12-01

Full Text Available This study compared niche breath, prey size, and diet variability in two pairs of sympatric species of terrestrial insectivorous birds, each pair containing one species that can persist in small forest fragments and one that does not. The pairs were Myrmeciza ferruginea and Sclerurus rufigularis; and Formicarius colma and F. analis, respectively. The prey availability in forest fragments was also sampled and compared to the availability in continuous forests. Niche breath indices did not differ between pair members, but diet variability differed in the opposite direction from that hypothesized. Although the two bird species most vulnerable to fragmentation fed on larger prey than less vulnerable species, prey availability, including that based on prey size did not differ among fragmented versus continuous forest sites. Thus, diet per se appeared not to be an important cause of extinction-proneness in these species. The simplest explanation proposed, that vulnerability to fragmentation was directly related to territory size, requires testing. However, it was consistent with observations that the bird species feeding on larger prey also need larger territories.Dieta e disponibilidade de presas de aves insetívoras terrestres em fragmentos florestais amazônicos. As aves insetívoras terrestres são um dos grupos mais vulneráveis à fragmentação de florestas tropicais; no entanto algumas espécies desta guilda ainda sobrevivem em fragmentos florestais e em florestas secundárias. Se a sensibilidade destas aves à fragmentação de florestas estivesse associada à dieta, então espécies com a dieta relativamente flexível teriam maior propensão em persistir nos fragmentos florestais. Este estudo comparou sobreposição trófica, amplitude de nicho, tamanho de presas e variabilidade de dieta de dois pares de espécies de aves insetívoras terrestres, onde cada par foi composto por uma espécie que persiste nos fragmentos e outra que n

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

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.

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.

Population variance in prey, diets and their macronutrient composition in an endangered marine predator, the Franciscana dolphin

Science.gov (United States)

Denuncio, Pablo; Paso Viola, Maria N.; Machovsky-Capuska, Gabriel E.; Raubenheimer, David; Blasina, Gabriela; Machado, Rodrigo; Polizzi, Paula; Gerpe, Marcela; Cappozzo, Humberto L.; Rodriguez, Diego H.

2017-11-01

Disentangling the intricacies governing dietary breadth in wild predators is important for understanding their role in structuring ecological communities and provides critical information for the management and conservation of ecologically threatened species. Here we combined dietary analysis, nutritional composition analysis of prey, literature data and nutritional geometry (right-angled mixture triangle models -RMT-) to examine the diet of the most threatened small cetacean in the western South Atlantic Ocean, the Franciscana dolphin (Pontoporia blainvillei). We applied a recently developed extension of niche theory based on the RMT to help understand the dietary strategies of this species. Our results showed that across their range the Franciscanas consumed prey with variable protein-to-lipid energy ratios (LMM, p < 0.001). In an intensive study of one area, FMA IV, we found that dolphins sub-populations, which recent genetic evidence suggest should be differentiated into three management units, have diets with different protein energy and water mass compositions, but similar protein-to-lipid energy ratios. Furthermore, dolphins from the three areas mixed different combinations of prey in their diets to achieve the observed macronutrient ratios. These results suggest that the different habitats that each sub-population occupies (estuarine, north marine area and south marine) might be associated with different prey composition niches, but similar realized nutritional niches. Future priorities are to better comprehend possible geographical and long-term seasonal effects on prey consumption and dietary breadth of the different Franciscana populations to identify potential impacts (environmental and human-related), enhance the current management strategies to protect this endangered marine predator.

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.

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.

PATTERNS OF PREY BIOMASS CONSUMPTION BY SMALL ODONTOCETES IN THE NORTHEASTERN COAST OF VENEZUELA

Directory of Open Access Journals (Sweden)

Lenin E. Oviedo Correa

2011-07-01

Full Text Available Trophic relationships are conditioned by population dynamics of interacting species in the community (species present, food web connections among them, and the strength of interactions, and on the consequences of these species interactions depend various ecosystem processes such as productivity and nutrient flux. Odontocetes target a wide range of prey items and are adapted to feeding at different depths. The aim of this report is to describe the patterns of prey consumption by small odontocetes, incorporating natural predatory patterns into a potential management scheme of strategic food sources, for both human and marine predators. Using the geo-statistical analysis tool of ArcGIS 9.2, maps illustrating the intensity and location of prey consumption were made for species with a sighting index (SPUE > 0.15. The biomass consumption emphasized the differences in habitat use by species. The trends in distribution of prey biomass removal by odontocetes particularly suggest a stratification of prey consumption primarily in shelf waters, with a prey biomass that is comprised basically by demersal fish and small pelagics (including Sardinella aurita, and into transition-oceanic depths where most of the predatory pattern would potentially rely on pelagic - mesopelagic squid and myctophids. Overall the spatial tendencies in regionalization presented in this contribution will serve as a base-line to assess ecosystem health and evaluate management scenarios.   Las relaciones tróficas son reguladas por la dinámica poblacional de las especies que interactúan dentro de la comunidad (especies presentes, conexiones interespecíficas, y nivel de interacción y de las consecuencias de esas interacciones para procesos del ecosistema como la productividad y el flujo de nutrientes. El objetivo de este reporte es evaluar el patrón de consumo de biomasa por odontocetos de menor tamaño en la costa Nororiental de Venezuela, incorporando patrones de depredaci

The effect of prey density on foraging mode selection in juvenile lumpfish: balancing food intake with the metabolic cost of foraging.

Science.gov (United States)

Killen, Shaun S; Brown, Joseph A; Gamperl, A Kurt

2007-07-01

1. In many species, individuals will alter their foraging strategy in response to changes in prey density. However, previous work has shown that prey density has differing effects on the foraging mode decisions of ectotherms as compared with endotherms. This is likely due to differences in metabolic demand; however, the relationship between metabolism and foraging mode choice in ectotherms has not been thoroughly studied. 2. Juvenile lumpfish Cyclopterus lumpus forage using one of two modes: they can actively search for prey while swimming, or they can 'sit-and-wait' for prey while clinging to the substrate using a ventral adhesive disk. The presence of these easily distinguishable foraging modes makes juvenile lumpfish ideal for the study of foraging mode choice in ectotherms. 3. Behavioural observations conducted during laboratory experiments showed that juvenile lumpfish predominantly use the 'cling' foraging mode when prey is abundant, but resort to the more costly 'swim' mode to seek out food when prey is scarce. The metabolic cost of active foraging was also quantified for juvenile lumpfish using swim-tunnel respirometry, and a model was devised to predict the prey density at which lumpfish should switch between the swim and cling foraging modes to maximize energy intake. 4. The results of this model do not agree with previous observations of lumpfish behaviour, and thus it appears that juvenile lumpfish do not try to maximize their net energetic gain. Instead, our data suggest that juvenile lumpfish forage in a manner that reduces activity and conserves space in their limited aerobic scope. This behavioural flexibility is of great benefit to this species, as it allows young individuals to divert energy towards growth as opposed to activity. In a broader context, our results support previous speculation that ectotherms often forage in a manner that maintains a minimum prey encounter rate, but does not necessarily maximize net energy gain.

Prey preference of the phytoseiid mite Typhlodromus pyri. 1. Response to volatile kairomones.

NARCIS (Netherlands)

Dicke, M.

1988-01-01

Using a Y-tube olfactometer, a study has been made of the response of females of the predatory miteTyphlodromus pyri Scheuten (Acarina: Phytoseiidae) to volatile kairomones of three prey species: the European red spider mite (Panonychus ulmi (Koch)), the two-spotted spider mite (Tetranychus urticae

Evaluation of INL Supplied MOOSE/OSPREY Model: Modeling Water Adsorption on Type 3A Molecular Sieve

Energy Technology Data Exchange (ETDEWEB)

Pompilio, L. M. [Syracuse University; DePaoli, D. W. [ORNL; Spencer, B. B. [ORNL

2014-08-29

The purpose of this study was to evaluate Idaho National Lab’s Multiphysics Object-Oriented Simulation Environment (MOOSE) software in modeling the adsorption of water onto type 3A molecular sieve (3AMS). MOOSE can be thought-of as a computing framework within which applications modeling specific coupled-phenomena can be developed and run. The application titled Off-gas SeParation and REcoverY (OSPREY) has been developed to model gas sorption in packed columns. The sorbate breakthrough curve calculated by MOOSE/OSPREY was compared to results previously obtained in the deep bed hydration tests conducted at Oak Ridge National Laboratory. The coding framework permits selection of various options, when they exist, for modeling a process. For example, the OSPREY module includes options to model the adsorption equilibrium with a Langmuir model or a generalized statistical thermodynamic adsorption (GSTA) model. The vapor solid equilibria and the operating conditions of the process (e.g., gas phase concentration) are required to calculate the concentration gradient driving the mass transfer between phases. Both the Langmuir and GSTA models were tested in this evaluation. Input variables were either known from experimental conditions, or were available (e.g., density) or were estimated (e.g., thermal conductivity of sorbent) from the literature. Variables were considered independent of time, i.e., rather than having a mass transfer coefficient that varied with time or position in the bed, the parameter was set to remain constant. The calculated results did not coincide with data from laboratory tests. The model accurately estimated the number of bed volumes processed for the given operating parameters, but breakthrough times were not accurately predicted, varying 50% or more from the data. The shape of the breakthrough curves also differed from the experimental data, indicating a much wider sorption band. Model modifications are needed to improve its utility and

Assimilation and partitioning of prey nitrogen within two anthozoans and their endosymbiotic zooxanthellae

Science.gov (United States)

Piniak, G.A.; Lipschultz, F.; McClelland, J.

2003-01-01

The movement of nitrogen from zooplankton prey into the temperate scleractinian coral Oculina arbuscula and the anemone Aiptasia pallida was measured using 15N-labeled brine shrimp. The efficiency with which prey nitrogen was incorporated into cnidarian tissues was species-specific. O. arbuscula with a full complement of zooxanthellae had an assimilation efficiency of nearly 100%, compared to only 46% for corals containing few zooxanthellae. In A. pallida, symbiont density had no effect, and nitrogen assimilation was 23 to 29%. In both species, the host retained the bulk of the ingested label. Complete digestion was rapid (zooxanthellae, where it was rapidly converted into macromolecules. Individual amino acids in A. pallida tissues were highly labeled with 15N within 4 h and showed no subsequent enrichment with time; however, zooxanthellae amino acids became increasingly enriched over 30 h. Differences in 15N enrichment among amino acids were consistent with known synthesis and transformation pathways, but it was not possible to discriminate between host feeding and de novo synthesis.

Preference alters consumptive effects of predators: top-down effects of a native crab on a system of native and introduced prey.

Directory of Open Access Journals (Sweden)

Emily W Grason

Full Text Available Top-down effects of predators in systems depend on the rate at which predators consume prey, and on predator preferences among available prey. In invaded communities, these parameters might be difficult to predict because ecological relationships are typically evolutionarily novel. We examined feeding rates and preferences of a crab native to the Pacific Northwest, Cancer productus, among four prey items: two invasive species of oyster drill (the marine whelks Urosalpinx cinerea and Ocenebra inornata and two species of oyster (Crassostrea gigas and Ostrea lurida that are also consumed by U. cinerea and O. inornata. This system is also characterized by intraguild predation because crabs are predators of drills and compete with them for prey (oysters. When only the oysters were offered, crabs did not express a preference and consumed approximately 9 juvenile oysters crab(-1 day(-1. We then tested whether crabs preferred adult drills of either U. cinerea or O. inornata, or juvenile oysters (C. gigas. While crabs consumed drills and oysters at approximately the same rate when only one type of prey was offered, they expressed a strong preference for juvenile oysters over drills when they were allowed to choose among the three prey items. This preference for oysters might negate the positive indirect effects that crabs have on oysters by crabs consuming drills (trophic cascade because crabs have a large negative direct effect on oysters when crabs, oysters, and drills co-occur.

Mechanisms and feasibility of prey capture in ambush-feeding zooplankton

DEFF Research Database (Denmark)

Kiørboe, Thomas; Andersen, Anders Peter; Langlois, Vincent

2009-01-01

Many marine zooplankters, particularly among copepods, are "ambush feeders" that passively wait for their prey and capture them by fast surprise attacks. This strategy must be very demanding in terms of muscle power and sensing capabilities, but the detailed mechanisms of the attacks are unknown...... of the examined species is close to this size limit and, in contrast to the larger species, uses its largest possible jump velocity for such attacks. The special requirements to ambush feeders with such attacks may explain why this strategy has evolved to perfection only a few times among planktonic suspension...... feeders ( few copepod families and chaetognaths)....

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...

Prey items and predation behavior of killer whales (Orcinus orca) in Nunavut, Canada based on Inuit hunter interviews

Science.gov (United States)

2012-01-01

Background Killer whales (Orcinus orca) are the most widely distributed cetacean, occurring in all oceans worldwide, and within ocean regions different ecotypes are defined based on prey preferences. Prey items are largely unknown in the eastern Canadian Arctic and therefore we conducted a survey of Inuit Traditional Ecological Knowledge (TEK) to provide information on the feeding ecology of killer whales. We compiled Inuit observations on killer whales and their prey items via 105 semi-directed interviews conducted in 11 eastern Nunavut communities (Kivalliq and Qikiqtaaluk regions) from 2007-2010. Results Results detail local knowledge of killer whale prey items, hunting behaviour, prey responses, distribution of predation events, and prey capture techniques. Inuit TEK and published literature agree that killer whales at times eat only certain parts of prey, particularly of large whales, that attacks on large whales entail relatively small groups of killer whales, and that they hunt cooperatively. Inuit observations suggest that there is little prey specialization beyond marine mammals and there are no definitive observations of fish in the diet. Inuit hunters and elders also documented the use of sea ice and shallow water as prey refugia. Conclusions By combining TEK and scientific approaches we provide a more holistic view of killer whale predation in the eastern Canadian Arctic relevant to management and policy. Continuing the long-term relationship between scientists and hunters will provide for successful knowledge integration and has resulted in considerable improvement in understanding of killer whale ecology relevant to management of prey species. Combining scientists and Inuit knowledge will assist in northerners adapting to the restructuring of the Arctic marine ecosystem associated with warming and loss of sea ice. PMID:22520955

The helminth fauna of birds of prey (Accipitriformes, Falconiformes and Strigiformes) in the Netherlands

NARCIS (Netherlands)

Borgsteede, F.H.M.; Okulewicz, A.; Zoun, P.E.F.; Okulewicz, J.

2003-01-01

Eighteen species of birds of prey in Netherlands were examined for helminth parasites: Accipitriformes - Accipiter gentilis (15 birds), A. nisus (9), Aquila pomarina (1), Buteo buteo (56), B. lagopus (4), Circaetus gallicus (2), Circus aeruginosus (2), C. cyaneus (3), Pernis apivorus (5);

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.

Zebra mussel beds: an effective feeding ground for Ponto-Caspian gobies or suitable shelter for their prey?

Science.gov (United States)

Kobak, Jarosław; Poznańska, Małgorzata; Jermacz, Łukasz; Kakareko, Tomasz; Prądzynski, Daniel; Łodygowska, Małgorzata; Montowska, Karolina; Bącela-Spychalska, Karolina

2016-01-01

Aggregations of the Ponto-Caspian invasive zebra mussel ( Dreissena polymorpha ) constitute a suitable habitat for macroinvertebrates, considerably increasing their abundance and providing effective antipredator protection. Thus, the overall effect of a mussel bed on particular predator species may vary from positive to negative, depending on both prey density increase and predator ability to prey in a structurally complex habitat. Alien Ponto-Caspian goby fish are likely to be facilitated when introduced into new areas by zebra mussels, provided that they are capable of utilizing mussel beds as habitat and feeding grounds. We ran laboratory experiments to find which prey (chironomid larvae) densities (from ca. 500 to 2,000 individuals m -2 ) in a mussel bed make it a more beneficial feeding ground for the racer goby Babka gymnotrachelus (RG) and western tubenose goby Proterorhinus semilunaris (WTG) compared to sandy and stone substrata (containing the basic prey density of 500 ind. m -2 ). Moreover, we checked how food availability affects habitat selection by fish. Mussel beds became more suitable for fish than alternative mineral substrata when food abundance was at least two times higher (1,000 vs. 500 ind. m -2 ), regardless of fish size and species. WTG was associated with mussel beds regardless of its size and prey density, whereas RG switched to this habitat when it became a better feeding ground than alternative substrata. Larger RG exhibited a stronger affinity for mussels than small individuals. WTG fed more efficiently from a mussel bed at high food abundances than RG. A literature review has shown that increasing chironomid density, which in our study was sufficient to make a mussel habitat an attractive feeding ground for the gobies, is commonly observed in mussel beds in the field. Therefore, we conclude that zebra mussels may positively affect the alien goby species and are likely to facilitate their establishment in novel areas, contributing to an

Zebra mussel beds: an effective feeding ground for Ponto-Caspian gobies or suitable shelter for their prey?

Directory of Open Access Journals (Sweden)

Jarosław Kobak

2016-11-01

Full Text Available Aggregations of the Ponto-Caspian invasive zebra mussel (Dreissena polymorpha constitute a suitable habitat for macroinvertebrates, considerably increasing their abundance and providing effective antipredator protection. Thus, the overall effect of a mussel bed on particular predator species may vary from positive to negative, depending on both prey density increase and predator ability to prey in a structurally complex habitat. Alien Ponto-Caspian goby fish are likely to be facilitated when introduced into new areas by zebra mussels, provided that they are capable of utilizing mussel beds as habitat and feeding grounds. We ran laboratory experiments to find which prey (chironomid larvae densities (from ca. 500 to 2,000 individuals m−2 in a mussel bed make it a more beneficial feeding ground for the racer goby Babka gymnotrachelus (RG and western tubenose goby Proterorhinus semilunaris (WTG compared to sandy and stone substrata (containing the basic prey density of 500 ind. m−2. Moreover, we checked how food availability affects habitat selection by fish. Mussel beds became more suitable for fish than alternative mineral substrata when food abundance was at least two times higher (1,000 vs. 500 ind. m−2, regardless of fish size and species. WTG was associated with mussel beds regardless of its size and prey density, whereas RG switched to this habitat when it became a better feeding ground than alternative substrata. Larger RG exhibited a stronger affinity for mussels than small individuals. WTG fed more efficiently from a mussel bed at high food abundances than RG. A literature review has shown that increasing chironomid density, which in our study was sufficient to make a mussel habitat an attractive feeding ground for the gobies, is commonly observed in mussel beds in the field. Therefore, we conclude that zebra mussels may positively affect the alien goby species and are likely to facilitate their establishment in novel areas

Arthropod prey of Wilson's Warblers in the understory of Douglas-fir forests

Science.gov (United States)

Hagar, J.C.; Dugger, K.M.; Starkey, E.E.

2007-01-01

Availability of food resources is an important factor in avian habitat selection. Food resources for terrestrial birds often are closely related to vegetation structure and composition. Identification of plant species important in supporting food resources may facilitate vegetation management to achieve objectives for providing bird habitat. We used fecal analysis to describe the diet of adult Wilson's Warblers (Wilsonia pusilla) that foraged in the understory of Douglas-fir (Pseudotsuga menziesii) forests in western Oregon during the breeding season. We sampled arthropods at the same sites where diet data were collected, and compared abundance and biomass of prey among seven common shrub species. Wilson's Warblers ate more caterpillars (Lepidoptera larvae), flies (Diptera), beetles (Coleoptera), and Homoptera than expected based on availability. Deciduous shrubs supported higher abundances of arthropod taxa and size classes used as prey by Wilson's Warblers than did evergreen shrubs. The development and maintenance of deciduous understory vegetation in conifer forests of the Pacific Northwest may be fundamental for conservation of food webs that support breeding Wilson's Warblers and other shrub-associated, insectivorous songbirds.

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'.

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.

Food resource and temporal partitioning amongst a guild of predatory agroecosystem - inhabiting ant species

Directory of Open Access Journals (Sweden)

Vivek Mohan AGARWAL, Neelkamal RASTOGI

2009-10-01

Full Text Available Prey diversity and temporal foraging patterns of six abundant, predatory ant species were investigated seasonally in an agroecosystem with two main vegetable crops. Pheidole sp. demonstrated the highest predation success and therefore appears to be the dominant species while Tapinoma melanocephalum showed the lowest success under the natural field conditions. Investigation of prey diversity and temporal activity patterns with the null model tests of niche overlap revealed a significant overlap indicating that the activity periods and prey diversity may not be solely influenced by interactions among the co-existing ant species. However, niche partitioning in the daily peak activity periods was demonstrated during all the three seasons (summer, rainy and winter particularly between Pheidole sp. and T. melanocephalum. Pheidole sp. exhibited a high intensity, broadly extended mono-modal foraging pattern. Camponotus compressus and C. paria showed bi-modality in their foraging activity during the rainy season and mono-modal patterns during summer and winter seasons. Pachycondyla tesserinoda, Tetramorium sp. and T. melanocephalum exhibited peak foraging activities in the morning hours during the summer and rainy seasons. The activity profiles of C. compressus and T. melanocephalum were skewed towards late afternoon hours during the winter season indicating avoidance of foraging activity during the favourable periods when the more aggressive Pheidole sp. is active. In the sponge gourd agroecosystem, the ants captured predominantly hymenopteran, orthopteran and coleopteran insects. While Pheidole sp. hunted mainly the large orthopteran prey, other ant species captured worker ants in the sponge gourd agroecosystem. In the cauliflower agroecosystem, while other species captured prey chiefly belonging to six orders, i.e., Lepidoptera, Hymenoptera, Coleoptera, Hemiptera, Isoptera and Diptera, Pheidole sp. was the only species to also hunt orthopteran prey

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

Dynamic complexities of a Holling II two-prey one-predator system with impulsive effect

International Nuclear Information System (INIS)

Song Xinyu; Li Yongfeng

2007-01-01

In this paper, we investigate the dynamic behaviors of a Holling II two-prey one-predator system with impulsive effect concerning biological control and chemical control strategies-periodic releasing natural enemies and spraying pesticide (or harvesting pests) at fixed time. By using the Floquet theory of linear periodic impulsive equation and small-amplitude perturbation we show that there exists a globally asymptotically stable two-prey eradication periodic solution when the impulsive period is less than some critical value. Further, we prove that the system is permanent if the impulsive period is larger than some critical value, and meanwhile the conditions for the extinction of one of the two prey and permanence of the remaining two species are given. Finally, numerical simulation shows that there exists a stable positive periodic solution with a maximum value no larger than a given level. Thus, we can use the stability of the positive periodic solution and its period to control insect pests at acceptably low levels

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.

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.

Prey size and availability limits maximum size of rainbow trout in a large tailwater: insights from a drift-foraging bioenergetics model

Science.gov (United States)

Dodrill, Michael J.; Yackulic, Charles B.; Kennedy, Theodore A.; Haye, John W

2016-01-01

The cold and clear water conditions present below many large dams create ideal conditions for the development of economically important salmonid fisheries. Many of these tailwater fisheries have experienced declines in the abundance and condition of large trout species, yet the causes of these declines remain uncertain. Here, we develop, assess, and apply a drift-foraging bioenergetics model to identify the factors limiting rainbow trout (Oncorhynchus mykiss) growth in a large tailwater. We explored the relative importance of temperature, prey quantity, and prey size by constructing scenarios where these variables, both singly and in combination, were altered. Predicted growth matched empirical mass-at-age estimates, particularly for younger ages, demonstrating that the model accurately describes how current temperature and prey conditions interact to determine rainbow trout growth. Modeling scenarios that artificially inflated prey size and abundance demonstrate that rainbow trout growth is limited by the scarcity of large prey items and overall prey availability. For example, shifting 10% of the prey biomass to the 13 mm (large) length class, without increasing overall prey biomass, increased lifetime maximum mass of rainbow trout by 88%. Additionally, warmer temperatures resulted in lower predicted growth at current and lower levels of prey availability; however, growth was similar across all temperatures at higher levels of prey availability. Climate change will likely alter flow and temperature regimes in large rivers with corresponding changes to invertebrate prey resources used by fish. Broader application of drift-foraging bioenergetics models to build a mechanistic understanding of how changes to habitat conditions and prey resources affect growth of salmonids will benefit management of tailwater fisheries.

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

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.

A phase transition induces chaos in a predator-prey ecosystem with a dynamic fitness landscape.

Science.gov (United States)

Gilpin, William; Feldman, Marcus W

2017-07-01

In many ecosystems, natural selection can occur quickly enough to influence the population dynamics and thus future selection. This suggests the importance of extending classical population dynamics models to include such eco-evolutionary processes. Here, we describe a predator-prey model in which the prey population growth depends on a prey density-dependent fitness landscape. We show that this two-species ecosystem is capable of exhibiting chaos even in the absence of external environmental variation or noise, and that the onset of chaotic dynamics is the result of the fitness landscape reversibly alternating between epochs of stabilizing and disruptive selection. We draw an analogy between the fitness function and the free energy in statistical mechanics, allowing us to use the physical theory of first-order phase transitions to understand the onset of rapid cycling in the chaotic predator-prey dynamics. We use quantitative techniques to study the relevance of our model to observational studies of complex ecosystems, finding that the evolution-driven chaotic dynamics confer community stability at the "edge of chaos" while creating a wide distribution of opportunities for speciation during epochs of disruptive selection-a potential observable signature of chaotic eco-evolutionary dynamics in experimental studies.