Kellen R. M. de Sousa
Full Text Available Imantodes cenchoa (Linnaeus, 1758 is distributed from the east coast of Mexico to Argentina. In Brazil, it occurs in the north, central-west and northeast regions. We present information on the reproductive biology and diet of I. cenchoa from analysis of 314 specimens deposited in the Herpetological Collection of the Museu Paraense Emílio Goeldi (MPEG. Imantodes cenchoa displays sexual dimorphism in the snout-vent length, where sexually mature females are larger than mature males (t = 4.02, p < 0.01; N males = 150, N females = 71, head length (f1.218 = 98.29, p < 0.01; N males = 150, N females = 71, and head width (f1.218 = 112.77, p < 0.01, N males = 150; N females = 71. Bi-sexual maturity is observed, with males becoming sexually mature earlier than females. Females with eggs were recorded from November to January (rainy season and from April to July (dry season, suggesting two reproductive peaks throughout the year, with recruitment occurring mainly during the rainy season, when there is a greater supply of food. Imantodes cenchoa is a nocturnal active forager, capturing prey that are asleep on the vegetation. In 32.80% of the analyzed specimens, food contents were present, of which 84.11% were lizards of the genera Norops (69.16%, N = 74 and Gonatodes (14.95%, N = 16. The other 15.89% of the contents were made up of items in an advanced state of digestion, preventing their identification. Some specimens had more than one food item in their digestive tract, accounting for 107 prey items in total. There was no ontogenetic variation in the diet of I. cenchoa, and the predominant direction of prey ingestion was antero-posterior (71.96%. Larger snakes tended to feed on larger prey, although these did not exclude small prey from their diet.
Henrique Caldeira Costa
é registrada da Amazônia ao norte, à Santa Catarina ao sul. No Estado de Minas Gerais, sudeste do Brasil, há apenas dois registros de I. cenchoa na literatura. No presente estudo, foi realizado um levantamento de I. cenchoa provenientes de Minas Gerais, nas principais coleções herpetológicas brasileiras, revelando um total de 13 localidades com registros desta espécie.
Savidge, J.A.; Stanford, J.W.; Reed, R.N.; Haddock, G.R.; Adams, A.A.Y.
We investigated canine teams (dogs and their handlers) on Guam as a potential tool for finding invasive brown treesnakes (Boiga irregularis) in the wild. Canine teams searched a 40 ?? 40 m forested area for a snake that had consumed a dead mouse containing a radio-transmitter. To avoid tainting the target or target area with human scent, no snake was handled or closely approached prior to searches. Trials were conducted during the morning when these nocturnal snakes were usually hidden in refugia. A radiotracker knew the snake's location, but dog handlers and search navigators did not. Of 85 trials conducted over four months, the two canine teams had an average success rate of 35% of correctly defining an area ??? 5 ?? 5 m that contained the transmittered snake; the team with more experience prior to the trials had a success rate of 44% compared with 26% for the less experienced team. Canine teams also found 11 shed skins from wild snakes. Although dogs alerted outside the vicinity of transmittered snakes, only one wild, non-transmittered snake was found during the trials, possibly reflecting the difficulty humans have in locating non-transmittered brown treesnakes in refugia. We evaluated success at finding snakes as a function of canine team, number of prior trials (i.e. experience gained during the trials), recent canine success at finding a target snake, various environmental conditions, snake perch height, and snake characteristics (snout-vent length and sex). Success rate increased over the course of the trials. Canine team success also increased with increasing average humidity and decreased with increasing average wind speed. Our results suggest dogs could be useful at detecting brown treesnakes in refugia, particularly when compared to daytime visual searches by humans, but techniques are needed to help humans find and extract snakes once a dog has alerted. ?? New Zealand Ecological Society.
Siers, Shane R; Savidge, Julie S; Reed, Robert N.
Roads have significant impacts on the dispersal of wildlife. Although this poses a threat to the abundance and diversity of desirable flora and fauna, it also affords some opportunity for enhancing control of invasive species. Roads are the most common terrain features that may affect the rate of landscape-scale movements of invasive Brown Treesnakes (Boiga irregularis) throughout Guam. We radio tracked 45 free-ranging Brown Treesnakes in close proximity to two roads in Guam and recorded instances where daily relocations of snakes spanned roads. Then we reconstructed observed movement histories with randomized turning angles, which served as a useful null hypothesis for assessing the effect of roads or road edge habitat on Brown Treesnake movement patterns. Random walk simulations demonstrated that Brown Treesnakes crossed these roads at a rate far lower than would be expected if snake movement was random with respect to roads and road edge habitat. We discuss two alternative hypotheses for these results: 1) habitat gaps posed by roads physically or behaviorally restrict snake movement; or 2) road edges provide preferred foraging habitat from which snakes are reluctant to depart. Because roads often form the boundaries of jurisdictional and management units, the effects of roads on the movement of invasive Brown Treesnakes will influence the prospects for success of future landscape-level suppression efforts.
Lardner, B.; Savidge, J.A.; Rodda, G.H.; Reed, R.N.; Yackel Adams, A.A.; Clark, C.S.
A bait tube is a device with which a toxicant inserted in a dead mouse (Mus musculus) can be delivered to invasive brown treesnakes (Boiga irregularis) with low risk of non-target bait take. We tested two bait tube designs in a 5ha snake enclosure where the identity of virtually every snake is known. Instead of using toxicants, we implanted radio transmitters in small (6.6±1.4 g) and large (21.8±2.9 g) bait mice. Knowing all snakes present in the population allowed us to characterize not only covariates of snakes taking bait, but also those of snakes evading our mock control effort, and if snake covariates interacted with any design variable in determining targeting rate. Tube design had no effect on take rate. Snake snout-vent length was a strong predictor of success: none of the 29 snakes smaller than 843 mm took any bait, while the 126 snakes ≥843 mm were responsible for a total of 164 bait takes. The smallest of these snakes were able to ingest small and large mice, but tended to consume small bait at a higher rate than large bait. The main reason for our failure to target smallest snakes appears not to be gape limitation, but rather that small snakes prefer other prey (lizards). The time it takes a snake to grow from the size threshold observed to the size of maturation has implications for the interval between discrete efforts using toxic bait. Targeting all snakes before reproduction can occur is highly desirable; otherwise, a new cohort of refractory snakes may enter the population.
499. Keiser, D., D. Keiser, and B. H. Brattstrom. 2011. Coluber (=Masticophis) flagellum (Coachwhip). Unusual feeding behavior. Herpetological ...juvenile Brown Treesnakes (Boiga irregularis). Herpetological Conservation and Biology 4:313-323. Rodda, G. H., K. Dean-Bradley, and T. H. Fritts...2005. Glueboards for estimating lizard abundance. Herpetological Review 36:252–259. Rodda, G. H., Fritts, T. H., Clark, C. S., Gotte, S. W. and Chiszar
Parker, M Rockwell; Patel, Saumya M; Zachry, Jennifer E; Kimball, Bruce A
Pheromones are useful tools for the management of invasive invertebrates, but have proven less successful in field applications for invasive vertebrates. The brown treesnake, Boiga irregularis, is an invasive predator that has fundamentally altered the ecology of Guam. The development of control tools to manage Boiga remains ongoing. Skin-based, lipophilic pheromone components facilitate mating in brown treesnakes, with females producing the same long-chain, saturated and monounsaturated (ketomonoene) methyl ketones known to function as pheromones in garter snakes, Thamnophis sirtalis. Boiga also express novel, diunsaturated methyl ketones (ketodienes) with a purported function as a sex pheromone. In our study, we implanted 17 β-estradiol in adult male brown treesnakes in order to manipulate methyl ketone expression as sex attractants, an effect that would mirror findings with garter snakes. Specifically, estrogen promoted production of two ketomonoenes, pentatriaconten-2-one and hexatriaconten-2-one, and suppressed production of one ketodiene, heptatriacontadien-2-one. In bioassays, estrogen-implanted males elicited tongue-flicking and chin rubbing behavior from unmanipulated males, though the responses were weaker than those elicited by females. On Guam, wild males exhibited greatest responses to whole female skin lipid extracts and only weak responses to the methyl ketone fractions from females and implanted males. Our results suggest that sex identity in brown treesnakes may be conferred by the ratio of ketomonoenes (female) to ketodienes (male) from skin lipids and may be augmented by a sex-specific endocrine signal (estradiol). However, a blend of long-chain methyl ketones alone is not sufficient to elicit maximal reproductive behaviors in male Boiga.
Clark, Larry; Shivik, John
Chemical irritants useful as repellents for brown treesnakes (Boiga irregularis) were identified. Exposure to various compounds produced a range of intensities for locomotory behavior in snakes. Essential oils comprised of 10 g liter-1 solutions of cedarwood, cinnamon, sage, juniper berry, lavender and rosemary each were potent snake irritants. Brown treesnakes exposed to a 2-s burst of aerosol of these oils exhibited prolonged, violent undirected locomotory behavior. In contrast, exposure to a 10 g liter-1 concentration of ginger oil aerosol caused snakes to locomote, but in a deliberate, directed manner. We also tested specific compounds, all derivative of food and flavor ingredients. 10 g liter-1 solutions delivered as aerosols of m-anisaldehyde, trans-anethole, cineole, cinnamaldehyde, citral, ethyl phenylacetate, eugenol, geranyl acetate or methyl salicylate all acted as potent irritants for brown treesnakes. The individual ingredients were classified using cluster analysis into groups that promoted different levels of response by snakes. This study is the first to systematically investigate the irritant potential of natural products for snakes. These data will be useful in the development of practical pest management tools for snakes.
Rodda, Gordon H.; Reed, Robert N.; Jarnevich, Catherine S.; Witmer, G.W.; Pitt, W. C.; Fagerstone, K.A.
Climate matching identifies extralimital destinations that could be colonized by a potential invasive species on the basis of similarity to climates found in the species’ native range. Climate is a proxy for the factors that determine whether a population will reproduce enough to offset mortality. Previous climate matching models (e.g., Genetic Algorithm for Rule-set Prediction [GARP]) for brown treesnakes (Boiga irregularis) were unsatisfactory, perhaps because the models failed to allow different combinations of climate attributes to influence a species’ range limits in different parts of the range. Therefore, we explored the climate space described by bivariate parameters of native range temperature and rainfall, allowing up to two months of aestivation in the warmer portions of the range, or four months of hibernation in temperate climes. We found colonization area to be minimally sensitive to assumptions regarding hibernation temperature thresholds. Although brown treesnakes appear to be limited by dry weather in the interior of Australia, aridity rarely limits potential distribution in most of the world. Potential colonization area in North America is limited primarily by cold. Climatically suitable portions of the United States (US) mainland include the Central Valley of California, mesic patches in the Southwest, and the southeastern coastal plain from Texas to Virginia.
Spencer, McKayka M.; Lardner, Bjorn; Mazurek, M.J.; Reed, Robert N.
Striking is a typical antipredator defense exhibited by many species of snakes. While trapping Brown Treesnakes (Boiga irregularis) on Guam, we observed that snakes most frequently struck at an approaching person at a site where snakes had been trapped, marked, and handled in the past. Using a combination of between-sites and within-site comparisons, we assessed if the propensity to strike was correlated with capture histories (both recent and long-term), snake size, body condition (a proxy to nutritional stress), sex, or tail condition (broken or intact), while controlling for confounding variables. We confirmed that propensity to strike was higher at the site where we had been conducting capture-mark-recapture for several years. However, we were unable to demonstrate a correlation between striking tendencies and individual recent or long-term capture histories. The only morphological covariate that had an effect on strike propensity was sex, with females striking more often than males. After removing the site effect from our model, we found that snakes missing parts of their tails were more likely to strike than snakes with intact tails. We have yet to identify the factor(s) that cause the pronounced difference across sites in snake propensity to strike, and data from additional sites might help elucidate any geographical patterns.
Lardner, Bjorn; Savidge, Julie A.; Rodda, Gordon H.; Reed, Robert N.
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.
Campbell, Earl W.; Yackel Adams, Amy A.; Converse, Sarah J.; Fritts, Thomas H.; Rodda, Gordon H.
The effect of predators on the abundance of prey species is a topic of ongoing debate in ecology; the effect of snake predators on their prey has been less debated, as there exists a general consensus that snakes do not negatively influence the abundance of their prey. However, this viewpoint has not been adequately tested. We quantified the effect of brown treesnake (Boiga irregularis) predation on the abundance and size of lizards on Guam by contrasting lizards in two 1-ha treatment plots of secondary forest from which snakes had been removed and excluded vs. two 1-ha control plots in which snakes were monitored but not removed or excluded. We removed resident snakes from the treatment plots with snake traps and hand capture, and snake immigration into these plots was precluded by electrified snake barriers. Lizards were sampled in all plots quarterly for a year following snake elimination in the treatment plots. Following the completion of this experiment, we used total removal sampling to census lizards on a 100-m2 subsample of each plot. Results of systematic lizard population monitoring before and after snake removal suggest that the abundance of the skink, Carlia ailanpalai, increased substantially and the abundance of two species of gekkonids, Lepidodactylus lugubris and Hemidactylus frenatus, also increased on snake-free plots. No treatment effect was observed for the skink Emoia caeruleocauda. Mean snout–vent length of all lizard species only increased following snake removal in the treatment plots. The general increase in prey density and mean size was unexpected in light of the literature consensus that snakes do not control the abundance of their prey species. Our findings show that, at least where alternate predators are lacking, snakes may indeed affect prey populations.
Mason, L.C.; Savidge, J.A.; Rodda, G.H.; Yackel Adams, A.A.
Current methods for controlling the invasive Brown Treesnake (Boiga irregularis) on Guam include a modified minnow trap with a live mouse lure. We investigated the effects on capture success of augmenting these traps with scented guide ropes leading to trap entrances. Initial screening of scent preferences was based on time spent in scented and unscented arms of a Y-maze. Preferences of large and small snakes were scored for six different prey scents (live and carrion gecko, skink, and mouse). Large snakes spent more time in the maze arm scented with live gecko and carrion gecko, whereas small snakes spent more time in the arm scented with carrion mouse and carrion gecko. After the laboratory study, a pilot trapping session was conducted in the field using three treatments (live mouse-scented ropes, carrion gecko-scented ropes, and carrion mouse-scented ropes) and two controls (traps with unscented guide ropes and those with no ropes attached). Contrary to laboratory results, live mouse-scented ropes were most effective. We conducted a second trapping session using live mouse-scented ropes as well as the two controls used in the pilot study. For snakes of below-average to average condition, the number of captures for traps with live mouse-scented ropes was higher than for traps with no ropes. However, for snakes of above-average condition, there were no differences in capture rates between trap treatments. Overall, treatment effects were weaker than latent individual heterogeneity and the influence of snake body size, with large snakes trapped more readily. ?? 2011 Society for the Study of Amphibians and Reptiles.
Pla, Davinia; Petras, Daniel; Saviola, Anthony J; Modahl, Cassandra M; Sanz, Libia; Pérez, Alicia; Juárez, Elena; Frietze, Seth; Dorrestein, Pieter C; Mackessy, Stephen P; Calvete, Juan J
The Brown Treesnake (Boiga irregularis) is an arboreal, nocturnal, rear-fanged venomous snake native to northern and eastern regions of Australia, Papua New Guinea and the Solomon Islands. It was inadvertently introduced onto the island of Guam during the late 1940's to early 1950's, and it has caused massive declines and extirpations of the native bird, lizard, and mammal populations. In the current study, we report the characterization of the venom proteome of an adult and a neonate B. irregularis specimens from Guam by a combination of venom gland transcriptomic and venomic analyses. Venom gland transcriptomic analysis of an adult individual identified toxins belonging to 18 protein families, with three-finger toxin isoforms being the most abundantly expressed transcripts, comprising 94% of all venom protein transcript reads. Transcripts for PIII-metalloproteinases, C-type lectins, cysteine-rich secretory proteins, acetylcholinesterases, natriuretic peptides, ficolins, phospholipase A 2 (PLA 2 ) inhibitors, PLA 2 s, vascular endothelial growth factors, Kunitz-type protease inhibitors, cystatins, phospholipase Bs, cobra venom factors, waprins, SVMP inhibitors, matrix metalloproteinases, and hyaluronidases were also identified, albeit, at very low abundances ranging from 0.05% to 1.7% of the transcriptome. The venom proteomes of neonate and adult B. irregularis were also both overwhelmingly (78 and 84%, respectively) dominated by monomeric and dimeric 3FTxs, followed by moderately abundant (21% (N) and 13% (A)) CRISPs, low abundance (1% (N), 3% (A)) PIII-SVMPs, and very low abundance (blot analysis showed that all venom proteins were recognized by anti-BTS IgGs, and cross-reactivity with other rear-fanged snake venoms was also observed. Incubation of anti-BTS venom IgGs with crude B. irregularis venom resulted in a significant decrease in proteolytic (SVMP) activity against azocasein. These results provide the first comparative venomic and anti-venomic analysis of
Richmond, Jonathan Q.; Wood, Dustin A.; Stanford, James W.; Fisher, Robert N.
The brown treesnake (Boiga irregularis) population on the Pacific island of Guam has reached iconic status as one of the most destructive invasive species of modern times, yet no published works have used genetic data to identify a source population. We used DNA sequence data from multiple genetic markers and coalescent-based phylogenetic methods to place the Guam population within the broader phylogeographic context of B. irregularis across its native range and tested whether patterns of genetic variation on the island are consistent with one or multiple introductions from different source populations. We also modeled a series of demographic scenarios that differed in the effective size and duration of a population bottleneck immediately following the invasion on Guam, and measured the fit of these simulations to the observed data using approximate Bayesian computation. Our results exclude the possibility of serial introductions from different source populations, and instead verify a single origin from the Admiralty Archipelago off the north coast of Papua New Guinea. This finding is consistent with the hypothesis thatB. irregularis was accidentally transported to Guam during military relocation efforts at the end of World War II. Demographic model comparisons suggest that multiple snakes were transported to Guam from the source locality, but that fewer than 10 individuals could be responsible for establishing the population. Our results also provide evidence that low genetic diversity stemming from the founder event has not been a hindrance to the ecological success of B. irregularis on Guam, and at the same time offers a unique ‘genetic opening’ to manage snake density using classical biological approaches.
Elden T Holldorf
Full Text Available Multiple host introductions to the same non-native environment have the potential to complete life cycles of parasites incidentally transported with them. Our goal was to identify a recently detected parasitic flatworm in the invasive Brown Treesnake (Boiga irregularis on the remote Pacific island of Guam. We considered possible factors influencing parasite transmission, and tested for correlations between infection status and potential indicators of host fitness. We used genetic data from the parasite and information about the native ranges of other possible non-native hosts to hypothesize how it arrived on Guam and how its life cycle may be currently supported.We identified the parasite by comparing larval morphology and mtDNA sequences with other Pseudophyllid tapeworms. We assessed probability of infection in individual snakes using logistic regression and examined different factors influencing presence of parasites in hosts.We identified the parasite as the pseudophyllid cestode Spirometra erinaceieuropaei, with all sampled worms from multiple snakes sharing a single mtDNA haplotype. Infection appears to be limited to the only freshwater watershed on the island, where infection prevalence was high (77.5%. Larger snakes had a higher probability of being infected, consistent with the chronic nature of such infections. While infection status was positively correlated with body condition, infected snakes tended to have lower intra-peritoneal fat body mass, potentially indicating a negative effect on energy stores.We discovered that B. irregularis inhabiting a small area of forested habitat in a freshwater watershed on Guam are often infected by a novel parasite of Asian origin. While further work is needed, this species of Spirometra, itself a non-native species, likely depends on a suite of recently introduced hosts from different parts of the world to complete the life cycle. This baseline study provides little evidence of any effects on host
Holldorf, Elden T; Siers, Shane R; Richmond, Jonathan Q; Klug, Page E; Reed, Robert N
Multiple host introductions to the same non-native environment have the potential to complete life cycles of parasites incidentally transported with them. Our goal was to identify a recently detected parasitic flatworm in the invasive Brown Treesnake (Boiga irregularis) on the remote Pacific island of Guam. We considered possible factors influencing parasite transmission, and tested for correlations between infection status and potential indicators of host fitness. We used genetic data from the parasite and information about the native ranges of other possible non-native hosts to hypothesize how it arrived on Guam and how its life cycle may be currently supported. We identified the parasite by comparing larval morphology and mtDNA sequences with other Pseudophyllid tapeworms. We assessed probability of infection in individual snakes using logistic regression and examined different factors influencing presence of parasites in hosts. We identified the parasite as the pseudophyllid cestode Spirometra erinaceieuropaei, with all sampled worms from multiple snakes sharing a single mtDNA haplotype. Infection appears to be limited to the only freshwater watershed on the island, where infection prevalence was high (77.5%). Larger snakes had a higher probability of being infected, consistent with the chronic nature of such infections. While infection status was positively correlated with body condition, infected snakes tended to have lower intra-peritoneal fat body mass, potentially indicating a negative effect on energy stores. We discovered that B. irregularis inhabiting a small area of forested habitat in a freshwater watershed on Guam are often infected by a novel parasite of Asian origin. While further work is needed, this species of Spirometra, itself a non-native species, likely depends on a suite of recently introduced hosts from different parts of the world to complete the life cycle. This baseline study provides little evidence of any effects on host fitness, but
Ivo Rohling Ghizoni-Jr
Full Text Available Roads cause diverse impacts to ecosystems, including habitat loss and fragmentation, alteration of the natural landscape and death of animals. However, little is known about the impact of this mortality on the animal populations. The snake fauna of the state of Santa Catarina is the least studied of southern Brazil. In this work we present data on 165 snakes of 38 species found dead on the roads of the state between 2003 and 2008, which corresponds to 50% of the snake species in relation to the expected occurrence for the state of Santa Catarina. The four most frequent species were Philodryas patagoniensis (n = 22; 13.33%, Liophis miliaris (n = 21; 12.72%, P. aestiva (n = 13; 7.87% and Bothrops jararaca (n = 12; 7.27%, which represent together about 41% of the snakes found dead on the roads. We extend the known distribution of Imantodes cenchoa by about 60km southward.
Full Text Available The morphology of many organisms seems to be related to the environment they live in. Nonetheless, many snakes are so similar in their morphological patterns that it becomes quite difficult to distinguish any adaptive divergence that may exist. Many authors suggest that the microornamentations on the scales of reptiles have important functional value. Here, we examined variations on the micromorphology of the exposed oberhautchen surface of dorsal, lateral, and ventral scales from the mid-body region of Xenodontinae snakes: Sibynomorphus mikani (terricolous, Imantodes cenchoa (arboreal, Helicops modestus (aquatic and Atractus pantostictus (fossorial. They were metallized and analyzed through scanning electron microscopy. All species displayed similar microstructures, such as small pits and spinules, which are often directed to the scale caudal region. On the other hand, there were some singular differences in scale shape and in the microstructural pattern of each species. S. mikani and I. cenchoa have larger spinules arranged in a row which overlap the following layers on the scale surface. Species with large serrate borders are expected to have more frictional resistance from the caudal-cranial direction. This can favor life in environments which require more friction, facilitating locomotion. In H. modestus, the spinules are smaller and farther away from the posterior rows, which should help reduce water resistance during swimming. The shallower small pits found in this species can retain impermeable substances, as in aquatic Colubridae snakes. The spinules adhering to the caudal scales of A. pantostictus seem to form a more regular surface, which probably aid their fossorial locomotion, reducing scale-ground friction. Our data appear to support the importance of functional microstructure, contributing to the idea of snake species adaptation to their preferential microhabitats.
Tobias Saraiva Kunz
Full Text Available http://dx.doi.org/10.5007/2175-7925.2009v22n2p91 Estradas causam diversos impactos aos ecossistemas, incluindo perda e fragmentação de hábitat, alteração da paisagem natural e morte de animais, sendo que pouco se sabe sobre o impacto destas mortes sobre as populações. A fauna de serpentes do Estado de Santa Catarina é a menos estudada do Sul do Brasil, não havendo estudos abordando serpentes atropeladas. Neste trabalho apresentamos dados sobre serpentes encontradas mortas em diversas estradas do Estado entre os anos de 2003 e 2008. Foram registrados 165 exemplares pertencentes a 38 espécies que correspondem a 50% das serpentes com ocorrência esperada para o Estado de Santa Catarina. As quatro espécies mais freqüentes foram Philodryas patagoniensis (N= 22; 13,33%, Liophis miliaris (n = 21; 12,72%, P. aestiva (n = 13; 7,87% e Bothrops jararaca (n = 12; 7,27%, que somadas representam cerca de 41% das serpentes encontradas mortas. Amplia-se ao sul a distribuição de Imantodes cenchoa em cerca de 60km.
Kilburn, Vanessa L; Ibáñez, Roberto; Green, David M
Chytridiomycosis, the disease caused by Batrachochytrium dendrobatidis, is considered to be a disease exclusively of amphibians. However, B. dendrobatidis may also be capable of persisting in the environment, and non-amphibian vectors or hosts may contribute to disease transmission. Reptiles living in close proximity to amphibians and sharing similar ecological traits could serve as vectors or reservoir hosts for B. dendrobatidis, harbouring the organism on their skin without succumbing to disease. We surveyed for the presence of B. dendrobatidis DNA among 211 lizards and 8 snakes at 8 sites at varying elevations in Panama where the syntopic amphibians were at pre-epizootic, epizootic or post-epizootic stages of chytridiomycosis. Detection of B. dendrobatidis DNA was done using qPCR analysis. Evidence of the amphibian pathogen was present at varying intensities in 29 of 79 examined Anolis humilis lizards (32%) and 9 of 101 A. lionotus lizards (9%), and in one individual each of the snakes Pliocercus euryzonus, Imantodes cenchoa, and Nothopsis rugosus. In general, B. dendrobatidis DNA prevalence among reptiles was positively correlated with the infection prevalence among co-occurring anuran amphibians at any particular site (r = 0.88, p = 0.004). These reptiles, therefore, may likely be vectors or reservoir hosts for B. dendrobatidis and could serve as disease transmission agents. Although there is no evidence of B. dendrobatidis disease-induced declines in reptiles, cases of coincidence of reptile and amphibian declines suggest this potentiality. Our study is the first to provide evidence of non-amphibian carriers for B. dendrobatidis in a natural Neotropical environment.
humans and have been implicated in the spread of infectious diseases to wildlife and domestic animals (Hone 1994, Feldman et al. 1995, Case 1996...poultry and other domesticated animals in Guam. Snake 23:75-80. Fritts, T. H. and G. H. Rodda. 1998. The role of introduced species in the...remain unclear. Numerous haemogregarine species use haematophagous arthropods (mosquitoes, sand flies, acarinids, and mites) to complete the life
any staff involved in toxicant application will need to take and pass the Guam Department of Agriculture, Pesticide Applicators Examination. Because... food cup) were evaluated (Savarie and Tope 2004). The highest entanglement in the canopy was only 60% (12 of 20) with the paper food cup. 23...bacterial degradation ) were evaluated, and in 2006, 4 commercial biodegradable paper products including single- and double-ender paper streamer marker flags
behavior and probably had little effect on bait consumption when they were used as solvent extracts of 48h aged DNM in experiment 3. Table 11...non-prey baits will enhance the bait take ( consumption ) by BTS. Technical Approach: Decomposition products from DNM carcasses aged for 48 h in an...from 48h aged DNM enhanced consumption of treated beef baits. In addition, volatile chemical recipes from 24h and 48h aged DNM were not effective bait
Solórzano López, Alejandro; Gutiérrez, José María; Cerdas Fallas, Luis
The karyotypes of five species of colubrid snakes from Costa Rica are as follows: Imuntodes cenchao and Drymobius margaritiferus have a diploid number of 36, with 16 macro- and 20 microchromosomes. The fourth pair is heteromorphic in females of I. cenchoa, with a metacentric Z and a submetacentric W chromosomes. Karyotypes of Erythrolampius bizonus and Leimadophis epinephalus have 28 chromosomes, without a clearcut separation between macro- and microchromosomes. In the case of E. bizomus, the...
Lardner, B.; Savidge, J.A.; Rodda, G.H.; Reed, R.N.; Adams, A.A.Y.
We conducted standardized visual searches at night for brown treesnakes (Boiga irregularis) and geckos, where we alternated between spotlight and floodlight lamps. Floodlights rendered us 25% more snakes and 71% more geckos than did spotlights. We show data on searcher variability and discuss what might affect the relative benefit of different lamp types. ?? 2009 Brill Academic Publishers.
INVESTMENT STRATEGY FY 2009 SERDP Annual Report 11 A Portable Fiberoptic Surface Enhanced Raman Sensor for Real-Time Detection and Monitoring of...United States (SI-1727), University of Arizona Purifying and Testing Gecko Skin Compounds, a Promising Attractant for Small Brown Treesnakes (SI... Multivariate Accelerated Corrosion Test Protocol (WP-1674), U.S. Air Force, Air Force Research Laboratory Wash Primer Replacement Based on the
Lardner, Björn; Reed, Robert N.; Adams, Amy A. Yackel; Mazurek, M.J.; Hinkle, Thomas J.; Levasseur, Patricia M.; Palmer, Meredith S.; Savidge, Julie A.
Two species of skinks (Fig. 1) occur in a 5-ha plot on Guam where we have been conducting intensive research on Brown Treesnake (Boiga irregularis) population biology for nearly a decade (Rodda et al. 2007). The Pacific Blue-tailed Skink (Emoia caeruleocauda [de Vis 1892]) is native to Guam, whereas the Curious Skink (Carlia ailanpalai Zug 2004) is invasive. On the evening of 27 November 2012, PML and MSP discovered a pile of vomited skinks (Fig. 2) inside the plot (UTM 55P: 269125 m E, 1508930 m N).
Torres-Carvajal, Omar; Echevarría, Lourdes Y.; Venegas, Pablo J.; Germán Chávez; Camper, Jeffrey D.
Abstract The discovery of three new species of Synophis snakes from the eastern slopes of the tropical Andes in Ecuador and Peru is reported. All previous records of Synophis bicolor from eastern Ecuador correspond to Synophis bogerti sp. n., which occurs between 1000–1750 m along a large part of the Amazonian slopes of the Ecuadorian Andes. In contrast, Synophis zamora sp. n. is restricted to southeastern Ecuador, including Cordillera del Cóndor, between 1543–1843 m. Synophis insulomontanus sp. n. is from the eastern slopes of the Andes in central and northern Peru, between 1122–1798 m, and represents the first record of Synophis from this country. All three new species share in common a large lateral spine at the base of the hemipenial body. A molecular phylogenetic tree based on three mitochondrial genes is presented, including samples of Diaphorolepis wagneri. Our tree strongly supports Synophis and Diaphorolepis as sister taxa, as well as monophyly of the three new species described here and Synophis calamitus. Inclusion of Synophis and Diaphorolepis within Dipsadinae as sister to a clade containing Imantodes, Dipsas, Ninia, Hypsiglena and Pseudoleptodeira is also supported. PMID:26798310
Siers, Shane R; Reed, Robert N.; Savidge, Julie A.
Roads are significant barriers to landscape-scale movements of individuals or populations of many wildlife taxa. The decision by an animal near a road to either cross or not cross may be influenced by characteristics of the road, environmental conditions, traits of the individual animal, and other aspects of the context within which the decision is made. We considered such factors in a mixed-effects logistic regression model describing the nightly road crossing probabilities of invasive nocturnal Brown Treesnakes (Boiga irregularis) through short-term radiotracking of 691 snakes within close proximity to 50 road segments across the island of Guam. All measures of road magnitude (traffic volume, gap width, surface type, etc.) were significantly negatively correlated with crossing probabilities. Snake body size was the only intrinsic factor associated with crossing rates, with larger snakes crossing roads more frequently. Humidity was the only environmental variable affecting crossing rate. The distance of the snake from the road at the start of nightly movement trials was the most significant predictor of crossings. The presence of snake traps with live mouse lures during a portion of the trials indicated that localized prey cues reduced the probability of a snake crossing the road away from the traps, suggesting that a snake's decision to cross roads is influenced by local foraging opportunities. Per capita road crossing rates of Brown Treesnakes were very low, and comparisons to historical records suggest that crossing rates have declined in the 60+ yr since introduction to Guam. We report a simplified model that will allow managers to predict road crossing rates based on snake, road, and contextual characteristics. Road crossing simulations based on actual snake size distributions demonstrate that populations with size distributions skewed toward larger snakes will result in a higher number of road crossings. Our method of modeling per capita road crossing
Gary W. WITMER, Pam L. FULLER
Full Text Available At least 1,065 introduced vertebrate species have been introduced in the United States and its territories, including at least 86 mammalian, 127 avian, 179 reptilian/amphibian, and 673 fish species. Examples in each major taxonomic group include domestic cat, small Indian mongoose, red fox, goat, pig, rabbit, rats, house mouse, gray squirrel, nutria, starling, Indian common myna, red-vented bulbul, brown treesnake, red-eared slider, brown trout, tilapia, and grass carp. We briefly review some of these species and the types of damage they cause. We then review the basic types of methods used for control or eradication of each taxonomic group, including physical, chemical, biological, and cultural methods. We discuss some of the challenges in managing these species, including issues with the use of toxicants, land access, public attitudes, and monitoring difficulties. Finally, we list some ongoing research and future research needs, including improved detection methods, improved attractants, improved barriers, improved capture methods, fertility control, and risk assessment methods [Current Zoology 57 (5: 559–567, 2011].
Reed, R.N.; Kraus, F.
In the annals of invasive species biology, higher taxa such asmammals, plants and insects have received the lion’s shareof research attention, largely because many of these invadershave demonstrated a remarkable ability to degrade ecosys-tems and cause economic harm. Interest in invasive reptilesand amphibians (collectively ‘herpetofauna’, colloquially‘herps’) has historically lagged but is now garnering in-creased scrutiny as a result of their escalating pace ofinvasion. A few herpetofaunal invaders have received con-siderable attention in scientiﬁc and popular accounts, in-cluding the brown treesnakeBoiga irregularison Guam,Burmese pythonPython molurusin Florida, Coqu´ıEleutherodactylus coquiin Hawaii and cane toadBufomarinusin Australia. However, relatively few are aware ofmany emerging and potentially injurious herpetofaunalinvaders, such as Nile monitorsVaranus niloticusin Flor-ida, common kingsnakesLampropeltis getulain the CanaryIslands, boa constrictorsBoa constrictoron Aruba andCozumel, or a variety of giant constrictor snakes in PuertoRico. For the vast majority of the most commonlyintroduced species, real or potential impacts to nativeecosystems or human economic interests are poorly under-stood and incompletely explored; major pathways of intro-duction have only recently been elucidated, and effectivemanagement interventions have been limited (Kraus, 2009).
Christy, M.T.; Yackel Adams, A.A.; Rodda, G.H.; Savidge, J.A.; Tyrrell, C.L.
For most ecologists, detection probability (p) is a nuisance variable that must be modelled to estimate the state variable of interest (i.e. survival, abundance, or occupancy). However, in the realm of invasive species control, the rate of detection and removal is the rate-limiting step for management of this pervasive environmental problem. For strategic planning of an eradication (removal of every individual), one must identify the least likely individual to be removed, and determine the probability of removing it. To evaluate visual searching as a control tool for populations of the invasive brown treesnake Boiga irregularis, we designed a mark-recapture study to evaluate detection probability as a function of time, gender, size, body condition, recent detection history, residency status, searcher team and environmental covariates. We evaluated these factors using 654 captures resulting from visual detections of 117 snakes residing in a 5-ha semi-forested enclosure on Guam, fenced to prevent immigration and emigration of snakes but not their prey. Visual detection probability was low overall (= 0??07 per occasion) but reached 0??18 under optimal circumstances. Our results supported sex-specific differences in detectability that were a quadratic function of size, with both small and large females having lower detection probabilities than males of those sizes. There was strong evidence for individual periodic changes in detectability of a few days duration, roughly doubling detection probability (comparing peak to non-elevated detections). Snakes in poor body condition had estimated mean detection probabilities greater than snakes with high body condition. Search teams with high average detection rates exhibited detection probabilities about twice that of search teams with low average detection rates. Surveys conducted with bright moonlight and strong wind gusts exhibited moderately decreased probabilities of detecting snakes. Synthesis and applications. By