Adult Snakes Research Articles

A 13-Year Study of A Northern Population of Twin-Spotted Rattlesnakes (Crotalus pricei): Growth, Reproduction, Survival, and Conservation

We conducted a 13-yr study of Crotalus pricei in Arizona's Chiricahua Mountains, capturing 306 individual snakes and recapturing snakes on 155 occasions. Juveniles shed and fed more frequently and grew more quickly than adults. Spiny lizard (Sceloporus) scales were found in 78% of fecal samples, making Sceloporus the most common prey item for both juveniles and adults. Males became larger than females at 5 yr of age, a year or two after females reached reproductive size. Although 45% of adult females were gravid, reproduction was not typically biennial and larger snakes were more likely to be gravid than smaller adult snakes. Survival rate (mean ± SE) at our most-studied site was 0.707 ± 0.0334 and detectability was 0.309 ± 0.0386; detectability was positively correlated with number of search hours and negatively correlated with dry weather. Mean population size at this site was 67 snakes, and there was no evidence of a population decline over the course of the study. However, age class structure was skewed toward younger snakes at the site, probably due to illegal collection of snakes for the pet trade.

Conspecific pheromone trailing and pheromone trail longevity in the African Colubrid Boaedon fuliginosus

In snakes, pheromone trailing is a strategy used for long-distance location of conspecifics. The two existing hypotheses for this behaviour are: a) to locate individuals for reproductive purposes; and b) to form aggregations during the winter/dry season. Pheromone trailing for reproductive purposes has been observed in over 20 snake species representing four different families. The ability of adult male African brown house snakes (Boaedon fuliginosus) to track a sexually attractive female (assumed to be producing pheromones), as well as a conspecific male, was tested using a standard Y-maze. The length of time a female's pheromone remained distinguishable to a male was also tested using the same methodology. Male B. fuliginosus showed a strong ability to trail females both immediately after the trail was left by a female (100%; n=14) and seven days after a female left a trail (100%; n=14). After 14 days, however, only 71.4% (n=14) of males chose the same arm as the female, demonstrating that the pheromone trail degraded over time. Males also trailed other males in 77.8% (n=18) of trials, which suggests that males may use other male trails to locate females, or navigate through unfamiliar territories.

Microbiological Evaluation of Different Strategies for Management of Snakes in Captivity

Keeping snakes in captivity to produce venom for scientific research and production of inputs is now a worldwide practice. Maintaining snakes in captivity involves capture, infrastructure investments, management techniques, and appropriate qualified personnel. Further, the success of the project requires knowledge of habitat, nutrition, and reproduction, and control of opportunistic infections. This study evaluated the management of snakes in three types of captivity (quarantine, intensive, and semiextensive) and diagnosed bacterial and fungal contaminants. A bacteriological profile was obtained by swabbing the oral and cloacal cavities, scales, and venoms of healthy adult snakes from Bothrops jararaca (Bj) and Crotalus durissus terrificus (Cdt). There was predominance of Enterobacteriaceae, especially non-fermenting Gram-negative bacilli excluding Pseudomonas spp and Gram- positive bacteria. Statistically, intensive captivity resulted in the highest number of bacterial isolates, followed by recent capture (quarantine) and by semiextensive captivity. No statistical difference was found between Bj and Cdt bacterial frequency. In vitro bacterial susceptibility testing found the highest resistance against the semisynthetic penicillins (amoxicillin and ampicillin) and highest sensitivity to amicacin and tobramycin aminoglycosides. To evaluate mycological profile of snakes from intensive captivity, samples were obtained from two healthy Bj and one B. moojeni, one B. pauloensis, and one Cdt showing whitish lesions on the scales suggestive of ringworm. Using conventional methods and DNA-based molecular procedures, five samples of Trichosporon asahii were identified. Despite the traditional role of intense captivity in ophidian venom production, semiextensive captivity was more effective in the present study by virtue of presenting superior control of bacterial and fungal transmission, easier management, lowest cost, and decreased rate of mortality; therefore, it should be considered as a good alternative for tropical countries.

Habitat fragmentation effects on annual survival of the federally protected eastern indigo snake

AbstractThe eastern indigo snake (Drymarchon couperi) is a federally listed species, most recently threatened by habitat loss and habitat degradation. In an effort to estimate snake survival, a total of 103 individuals (59 males, 44 females) were followed using radio‐tracking fromJanuary 1998 toMarch 2004 in three landscape types that had increasing levels of habitat fragmentation: (1) conservation cores; (2) conservation areas along highways; (3) suburbs. Because of a large number of radio‐tracking locations underground for which the state of snakes (i.e. alive or dead) could not be assessed, we employed a multistate approach to model snake apparent survival and encounter probability of live and dead snakes. We predicted that male snakes in suburbs would have the lowest annual survival. We found a transmitter implantation effect on snake encounter probability, as snakes implanted on a given occasion had a lower encounter probability on the next visit compared with snakes not implanted on the previous occasion. Our results indicated that adult eastern indigo snakes have relatively high survival in conservation core areas, but greatly reduced survival in conservation areas along highways and in suburbs. These findings indicate that habitat fragmentation is likely to be the critical factor for species’ persistence.

Food resources influence spatial ecology, habitat selection, and foraging behavior in an ambush-hunting snake (Viperidae: Bothrops asper): an experimental study

Prey availability affects many aspects of predators’ life history and is considered a primary factor influencing individuals’ decisions regarding spatial ecology and behavior, but few experimental data are currently available. Snakes may represent ideal model organisms relative to other animal groups for addressing such resource dependency, due to a presumably more direct link between food resources and many aspects of behavior and natural history. We experimentally investigated the relationship between food intake and spatial behavior in a population of the snake Bothrops asper in a Costa Rican lowland rainforest. Six adult snakes were allowed to forage naturally while six were offered supplemental food in the field, with both groups monitored using radiotelemetry. Mean home range size did not differ between groups presumably due to small sample size, but supplementally fed snakes demonstrated altered patterns of macro- and microhabitat selection, shorter and less frequent movements, and increased mass acquisition. Fed snakes also devoted less time to foraging efforts, instead more frequently remaining inactive and utilizing shelter. Because snakes were always fed in situ and not at designated feeding stations, observed shifts in habitat selection are not explained by animals simply moving to areas of higher food availability. Rather, B. asper may have moved to swamps in order to feed on amphibians when necessary, but remained in preferred forest habitat when food was otherwise abundant. The strong behavioral and spatiotemporal responses of snakes in this population may have been influenced by an overall scarcity of mammalian prey during the study period.

Mortality Patterns and the Cost of Reproduction in a Northern Population of Ratsnakes, Elaphe obsoleta

Abstract A recent study of Ratsnakes (Elaphe obsoleta) in Texas found that adult mortality was higher for females than males, consistent with the cost of reproduction in snakes being higher for females. To determine whether the same pattern prevailed in a northern population of Ratsnakes, we used data collected using radio-telemetry to test several predictions of the cost-of-reproduction hypothesis. Contrary to there being a cost to reproduction, mortality rates did not differ between juvenile and adult snakes and, contrary to females having a higher cost of reproduction, mortality rates among adults did not differ between males and females. The only evidence consistent with reproduction increasing mortality risk was higher winter mortality for females in poor condition following egg laying. Mortality did not vary with activity but increased with time spent basking, although group differences in basking were not sufficient to produce differences in mortality. High risk of winter mortality in this populati...

How to make a sexy snake: estrogen activation of female sex pheromone in male red-sided garter snakes

Vertebrates indicate their genetic sex to conspecifics using secondary sexual signals, and signal expression is often activated by sex hormones. Among vertebrate signaling modalities, the least is known about how hormones influence chemical signaling. Our study species, the red-sided garter snake (Thamnophis sirtalis parietalis), is a model vertebrate for studying hormonal control of chemical signals because males completely rely on the female sex pheromone to identify potential mates among thousands of individuals. How sex hormones can influence the expression of this crucial sexual signal is largely unknown. We created two groups of experimental males for the first experiment: Sham (blank implants) and E2 (17β-estradiol implants). E2 males were vigorously courted by wild males in outdoor bioassays, and in a Y-maze E2 pheromone trails were chosen by wild males over those of small females and were indistinguishable from large female trails. Biochemically, the E2 pheromone blend was similar to that of large females, and it differed significantly from Shams. For the second experiment, we implanted males with 17β-estradiol in 2007 but removed the implants the following year (2008; Removal). That same year, we implanted a new group of males with estrogen implants (Implant). Removal males were courted by wild males in 2008 (implant intact) but not in 2009 (removed). Total pheromone quantity and quality increased following estrogen treatment, and estrogen removal re-established male-typical pheromone blends. Thus, we have shown that estrogen activates the production of female pheromone in adult red-sided garter snakes. This is the first known study to quantify both behavioral and biochemical responses in chemical signaling following sex steroid treatment of reptiles in the activation/organization context. We propose that the homogametic sex (ZZ, male) may possess the same targets for activation of sexual signal production, and the absence of the activator (17β-estradiol in this case) underlies expression of the male phenotype.

Survival and population growth of a long‐lived threatened snake species,Drymarchon couperi(Eastern Indigo Snake)

AbstractDemographic data provide a basis for understanding the life history and ecology of species, factors which are vital for informing conservation efforts; however, little is known regarding the population ecology of most snake species, including the threatened Eastern Indigo Snake (Drymarchon couperi). We used 11 years (1999–2009) of capture‐mark‐recapture (CMR) and 2.5 years (2003–2005) of radiotelemetry data from southeastern Georgia, USA, in a CMR modeling framework to estimate apparent survival, capture and transition probabilities, and evaluate factors influencing these parameters. The model‐averaged estimate of overall apparent annual survival probability was 0.700 (±0.030 SE) and is comparable to that obtained from known fate analysis (radiotelemetry) at the same site. Body size positively influenced survival, regardless of sex. Capture probability differed seasonally by sex, suggesting lower capture probability for females in fall and males in winter. There was no evidence for effect of precipitation or site‐specific differences in survival. Model averaged estimate of annual adult survival estimated using multistate CMR models was 0.738 ± 0.030 and 0.515 ± 0.189 for subadults. We estimated population growth rate (λ) and elasticity (proportional sensitivity) ofλto vital rates using a stage‐structured matrix population model. Population growth rate ranged from 0.96 to 1.03 depending on the value of the probability of transitioning from subadult to adult stage. Theλwas proportionally most sensitive to changes in adult survival rate, followed by subadult survival. Our results suggest that protecting adult snakes and their habitats would result in the highest likelihood of long‐term population stability and growth.

Is it better in the moonlight? Nocturnal activity of insular cottonmouth snakes increases with lunar light levels

AbstractBoth theoretical and empirical investigations suggest that predation risk and availability of resources interact as trade‐offs to produce patterns of predation‐sensitive foraging. Such interactions have been explored intensely in terrestrial predator–prey systems where both nocturnal prey and predators adjust their activity and foraging behaviour to levels of moonlight. In the case of prey, higher levels of moonlight increase predation risks, and thus prey display lower levels of activity and/or shifts in their use of microhabitat during full moon nights. Predators also display parallel modifications of their activity rhythms during full moon nights – but why? Are predators also sensitive to increased predation, or do predators adjust their behaviour to that of their prey in order to optimize foraging success? Herein, we examined nocturnal predatory behaviour in a natural system where insular cottonmouth snakes, Agkistrodon piscivorus conanti, forage for fish carrion that is indifferent to levels of moonlight, thereby removing complexities linked to the behavioural patterns of prey. Our results demonstrated that insular cottonmouths increase their activity during full moon nights. Predation pressure on snakes foraging in the open does not seem to drive their nocturnal behaviour insofar as small‐sized individuals – presumably more susceptible to predation – are equally abundant as adult snakes irrespective of levels of moonlight. These results suggest that variation in predator's activity in natural predator–prey systems during risky (full moon) nights might be attributable principally to the availability and detectability of prey rather than a foraging‐safety trade‐off specific to the predator.

Rattle Button Loss in Juvenile Ridge-nosed Rattlesnakes (Crotalus willardi): A Novel Mechanism for the Developmental Delay of the Rattle

Although a keratinous rattle structure at the end of the tail is the defining trait of rattlesnakes, there is variation in the ability of rattles to produce sound. In previously reported cases of reduced rattle functionality, near complete loss of sound production occurs in adult snakes that do not retain loose interlocking rattle segments. Here we report for the first time a distinct phenomenon: the delay in development of a functional rattle among neonate and juvenile Ridge-nosed Rattlesnakes (Crotalus willardi) resulting from universal loss of the rattle button, normally the first loose segment retained in functional rattles. Loose segments added during subsequent sheds are retained at rates similar to two other rattlesnake species examined (based on data from over 1,000 wild-caught rattlesnakes) and presumably other rattlesnakes with sound-producing rattles. This pattern of delayed rattle development results in effectively silent cohorts for approximately the first year of life and provides further insight into the ecological context of rattle function and evolution.

Digestive performance in neonatal Southern Pacific Rattlesnakes (Crotalus oreganus helleri)

Despite significant research on the metabolic characteristics of digestion in adult snakes, the digestive performance of neonatal snakes is poorly characterized. We examined the energetic costs associated with digestion and the energetic profit derived from the first meal eaten by neonatal Southern Pacific Rattlesnakes ( Crotalus oreganus helleri Meek, 1905). Composition of venom of C. o. helleri changes through ontogeny, becoming richer in proteolytic components that are hypothesized by some to enhance the rate of digestion. Therefore, we also investigated whether venom type (proteolytic-component-rich “adult” versus neurotoxin-rich “neonate” venom) affected digestive performance. We examined specific dynamic action (SDA), apparent assimilation efficiency, rate of digestion, and gut passage time in snakes fed prey killed with either “adult” or “neonate” venom at 22 and 30 °C. Although digestion progressed more quickly at 30 °C compared with 22 °C, there were no significant differences in digestion rate or assimilation efficiency owing to venom type; however, our statistical power was limited by small sample size. Despite the lack of “digestive experience”, the apparent assimilation efficiency was remarkably high (mean of 92%) and greater than published values for Crotalinae species. Based on these results, we hypothesize that neonatal C. o. helleri make a big energetic profit from their first meal by digesting efficiently and economically.

Proteomic analysis of ontogenetic and diet-related changes in venom composition of juvenile and adult Dusky Pigmy rattlesnakes (Sistrurus miliarius barbouri)

Snake venom proteins show high levels of variation at the level of the individual yet the environmental and molecular mechanisms that generate this diversity remain unclear. Here we report the results of a controlled feeding experiment combined with proteomic analyses of periodically collected venom samples to assess the roles of ontogenetic and diet-related effects on venom composition of captive juvenile and adult Dusky Pigmy rattlesnakes (Sistrurus miliarius barbouri). Juvenile snakes fed from birth with mice, lizards, or frogs showed little evidence for an ontogenetic shift in venom composition from 5 to 26 months in terms of substantial changes in the relative abundance of major classes of venom toxins. However, there were fine-scale changes in the relative abundance of D49-PLA₂ 15, PI-SVMPs, and PIII-SVMP 28, and a decline in the abundance of other PIII-SVMPs. Although juveniles raised on different prey exhibited distinct relative toxin compositional change rates, at 26 months old, their venoms showed similar patterns of protein composition suggesting little effect of diet on the overall make-up of venom in snakes this age or younger. In contrast, adult females raised on different prey over a 26 month period showed prey-related changes in the relative abundance of major protein families from initial to final samples. Specifically, mouse-fed females showed substantial increases in the relative abundance of total PLA₂s and serine proteinases of 95% and >100%, respectively, whereas comparable values for lizard- (42% and -22%) and frog-fed females (2% and 11%) were distinctly smaller in magnitude. Venom from adult snakes fed on different prey also showed distinct changes in the abundance of PLA₂ molecules 15, 19a, and 19, which were, respectively, (>100%, 33%, 63%), (>100%, 0%, 35%), and (71%, 20%, -4%) for the mice-, lizard-, and frog-diet. Venom from snakes raised on frogs contained a small (1.1%) but consistent amount of a PLA₂ molecule (15a) not present in snakes fed on mice or lizards. This work provides evidence that venom composition is somewhat plastic in both juvenile and adult S. m. barbouri and that, at least in adults, prey consumed may influence the relative abundance of possibly functionally-distinct classes of venom proteins.

Long‐term population dynamics in a Mediterranean aquatic snake

AbstractA review of several long‐term studies has recently suggested that snakes might be declining in large parts of the world. Additional data from other long‐term studies are therefore urgently needed in order to assess the generalities of such suggested declines. Based on a 20‐year study, we analyzed demographic data on adult dice snakes (Natrix tessellata) studied in central Italy between 1985 and 2004. Both male and female dice snakes were relatively long‐lived, with no significant differences in longevity between the sexes. Individual males and females were observed over a maximum of 10 and 14 years, respectively. However, the among‐year recapture rates between the year the snakes were initially captured and the subsequent year (i.e., year 1 to year 2) was significantly lower (45%) than the among‐year recapture rates during subsequent years (74%; i.e., year 2 to year 3), suggesting that a large proportion of the snakes at first capture were in fact not resident within our study area, and hence many snakes were migrating in and out of our 2‐km stream study site, with no inter‐sexual difference in dispersal rates. Sex ratio was virtually equal if we consider the study period as a whole. Significant annual fluctuations were, however, observed through the study. In 1985–1990, 1993–1995, 1998 and 1999 the sex ratio was male‐biased, whereas in 2000–2004 female‐biased. In terms of both survival and recapture probabilities, model selection showed that Akaike's information criterion favored the model incorporating body size, with the model incorporating year having an intermediate likelihood, and the model with sex included being the most disfavored. Total population number estimates suggest an average 86 adult individuals along the 2 km of stream with only minor annual variations. However, a significant decrease in the number of males occurred during the last 6 years of our study. Thus, further monitoring of this population is warranted in light of the decline of snake populations reported recently.

Determination of Plasma Osmolality and Agreement between Measured and Calculated Values in Captive Male Corn Snakes (Pantherophis [Elaphe] guttatus guttatus)

Abstract Twelve adult male corn snakes, Pantherophis (Elaphe) guttatus guttatus, were used for this study. Blood samples were collected via cardiocentesis or caudal tail venipuncture. Plasma chemistries were measured using a standard laboratory chemistry analyzer; these parameters were used to calculate plasma osmolality. Osmolality also was measured using a freezing point osmometer. The osmolality measured with the osmometer in the corn snakes ranged from 304.5 to 373.0 mOsm/kg, with a mean value of 344.5 mOsm/kg. These values are higher than the osmolality of Ringer's solution (310 mOsm/L), lactated Ringer's solution (272 mOsm/L), Plasma-Lyte A® (294 mOsm/L), and Normosol R® (295 mOsm/L) and should be taken into account when replenishing fluids to avoid large shifts in plasma osmolality. Bland Altman plots were used to assess the level of agreement between the measured and calculated osmolalitites. The results of the comparisons showed the highest level of agreement between the measured and calculated o...

Evolutionary persistence of chemically elicited ophiophagous antipredator responses in gartersnakes (Thamnophis sirtalis).

The ability to detect and respond to potential predators is key for the survival of individuals, but this ability is sometimes lost via relaxation of antipredator behavior when prey species are separated from predators. Adult and predator-naïve neonate gartersnakes (Thamnophis sirtalis) from mainland and insular sites where they do and do not occur with ophiophagous (snake-eating) snakes were tested to determine if responses to such predators have been lost, reduced, or retained, and what might be causing differences in such responses. Our data indicate that, overall, adult snakes from populations syntopic with ophiophagous milksnakes are more responsive to chemical stimuli from milksnakes than adults from areas where they are not syntopic with milksnakes, whereas there were few differences with neonate gartersnakes. Experiments with neonates with or without periodic ophiophagous snake chemical experience over several weeks showed that gartersnakes with such experience became more responsive to ophiophagous cues rather than habituating to them. Such evidence of both genetic and experiential factors underlying the antipredator responses to ophiophagous snakes indicates that antipredator responses have persisted despite separation of predator and prey.

ALTERED NAVIGATIONAL DEMANDS INDUCE CHANGES IN A CORTICAL BRAIN REGION OF FREE-RANGING NORTHERN PACIFIC RATTLESNAKES (CROTALUS O. OREGANUS)

Event Abstract Back to Event ALTERED NAVIGATIONAL DEMANDS INDUCE CHANGES IN A CORTICAL BRAIN REGION OF FREE-RANGING NORTHERN PACIFIC RATTLESNAKES (CROTALUS O. OREGANUS) Matthew L. Holding1*, Kelsee M. Buskirk1, Emily N. Taylor1 and Christine R. Strand1 1 California Polytechnic State University, Biological Sciences, United States The cortical telencephalon of squamate reptiles has been implicated as a functional homologue to the avian and mammalian hippocampus. The role of the medial and dorsal cortices in spatial navigation and spatial memory has been demonstrated by multiple laboratory experiments and observational studies in the field. This study sought to experimentally manipulate the navigational demands placed on free-ranging northern Pacific rattlesnakes (Crotalus o. oreganus) to provide direct evidence of the relationship between spatial demands and neuroplasticity in the cortical telencephalon of the squamate brain. Twenty-two adult male snakes were radio-tracked for two months during which one of three treatments was imposed weekly. Treatments consisted of the following: 225 meter translocation in a random direction, 225 meter walk and release at that day’s capture site (handling control), and undisturbed control. Snakes were then sacrificed and brains were removed, embedded in gelatin, frozen, sectioned and Nissl-stained for quantification of cortical volumes. The volume of the medial cortex was significantly larger in the translocated group compared to undisturbed controls. No differences in dorsal or lateral cortical volume were detected among the groups. The range of the snakes measured by minimum convex polygon was larger in the translocated group compared to handled and undisturbed controls. A causal relationship between increased navigation in a free-ranging reptile and changes in brain morphology has been established. Furthermore, sex differences previously described in the medial cortex of Crotaline snakes may be a function of an increased amount of movement in males and not a genetically determined dimorphism. Acknowledgements National Science Foundation Pre-doctoral Fellowship to MLH Keywords: Medial Cortex, neuroplasticity, reptile, Spatial Ecology, translocation Conference: ISAREN 2011: 7th International Symposium on Amphibian and Reptilian Endocrinology and Neurobiology, Ann Arbor, United States, 11 Jul - 13 Jul, 2011. Presentation Type: Poster Topic: Brain and behavior Citation: Holding ML, Buskirk KM, Taylor EN and Strand CR (2011). ALTERED NAVIGATIONAL DEMANDS INDUCE CHANGES IN A CORTICAL BRAIN REGION OF FREE-RANGING NORTHERN PACIFIC RATTLESNAKES (CROTALUS O. OREGANUS). Front. Endocrinol. Conference Abstract: ISAREN 2011: 7th International Symposium on Amphibian and Reptilian Endocrinology and Neurobiology. doi: 10.3389/conf.fendo.2011.03.00019 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Jul 2011; Published Online: 09 Aug 2011. * Correspondence: Mr. Matthew L Holding, California Polytechnic State University, Biological Sciences, San Luis Obispo, CA, 93407-0401, United States, matthew.holding28@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Matthew L Holding Kelsee M Buskirk Emily N Taylor Christine R Strand Google Matthew L Holding Kelsee M Buskirk Emily N Taylor Christine R Strand Google Scholar Matthew L Holding Kelsee M Buskirk Emily N Taylor Christine R Strand PubMed Matthew L Holding Kelsee M Buskirk Emily N Taylor Christine R Strand Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Comparison of Bothropoides jararaca bites with and without envenoming treated at the Vital Brazil Hospital of the Butantan Institute, State of São Paulo, Brazil

This study analyses the cases of all bites (including dry bites) caused by Bothropoides jararaca attended at the Vital Brazil Hospital of the Butantan Institute, State of São Paulo, Brazil. A retrospective study was conducted of patients bitten by Bothropoides jararaca (n=792) from January 1990 to December 2004. The characteristics of the snake specimen, data related to the accident and clinical manifestations on admission were obtained from patient medical records. The majority of the cases in this study were caused by female and juvenile snakes. No stomach contents were found in 93.4% of the snake specimens after dissection. No statistical difference was observed between the occurrence of dry bites and the maturity or sex of the snake. The median SVL of snakes in mild and moderate cases was 40.5 cm and in severe cases, SVL increased to 99 cm. Necrosis was more common in the digits of the feet and hands (4.8%) compared to the other body regions (1.8%). A significant difference was verified between severity and a time interval greater than six hours from the bite to hospital admission. A significant association was verified between gingival bleeding and abnormal blood coagulability. In accidents caused by adult snakes, necrosis was more frequent (7.2%) compared to accidents caused by juvenile snakes (1%). In this work, the association between certain epidemiological data and the evolution of biological parameters in the clinical course of Bothrops sensu latu accidents were highlighted, contributing to the improvement of snake bite assistance.

Use of Statistical Bootstrapping to Calculate Confidence Intervals for the Fall Chinook Salmon Run Reconstruction to Lower Granite Dam

AbstractMeeting escapement and recovery goals for Pacific salmon Oncorhynchus spp. is greatly facilitated by accurate and precise estimates of run size and stock composition. Although this is particularly important for endangered Pacific salmon runs like the Snake River fall Chinook salmon O. tshawytscha evolutionarily significant unit, few studies provide estimates with confidence intervals (CIs) and standard errors (SEs). We developed a run reconstruction method for fall Chinook salmon returning to Lower Granite Dam on the Snake River. We showed that composition estimates of fish returning to large river systems can be obtained through subsampling. The methods reported here yield CIs around those estimates. We used compound bootstrap methods to derive CIs and SEs on return numbers and composition. In general, if the number of fish returning for a group was 300 or more, we were 90% confident that our return estimate represented the true number within 10%. Estimates for smaller groups were generally imprecise. The analytical technique described here provides fishery managers with information necessary for assessing escapement and recovery goals and addressing conservation and harvest allocations of adult Snake River fall Chinook salmon.

Summer and Winter Spatial Habitat Use by the Lake Erie Watersnake

Abstract In an effort to provide information to guide habitat management for the Lake Erie watersnake Nerodia sipedon insularum, a federally threatened and Ohio state endangered species, we used radiotelemetry to obtain spatial habitat data for adult snakes during the summer active season and during winter hibernation. During the summer active season, terrestrial habitat use was limited to a narrow band of shoreline. Among individuals, maximum distance inland from shore ranged from 1 to 50 m (mean = 8 m) and linear extent of shoreline ranged from 30 to 1,360 m (mean = 261 m). Winter hibernation occurred at varying distances inland with individual hibernation sites ranging from 1 to 580 m (mean = 29 m) from shore. Habitat use did not differ between males and females. Existing U.S. Fish and Wildlife Service habitat management guidelines suggest that ground-disturbing activities within potential hibernation areas (defined as terrestrial habitat within 161 m of shore) should be avoided in winter to prevent harm to hibernating snakes. They suggest further that excavation and removal of shrubs, standing or downed trees, root masses, animal burrows, piled rocks, cliffs, or bedrock within 21 m of shore should be avoided in summer to prevent harm to active snakes. Given that Lake Erie watersnakes have recovered to the point where delisting is being proposed, these habitat guidelines appear to be sufficient. However, maintaining voluntary compliance with habitat guidelines and meeting the need for continued public outreach will be vital to ensure long-term persistence.

Metabolism, Body Size and Life Span: A Case Study in Evolutionarily Divergent Populations of the Garter Snake (Thamnophis elegans)

We present a case study of metabolism, life history and aging in the western terrestrial garter snake (Thamnophis elegans). Early research in the field supported the rate-of-living hypothesis as an explanation of aging, which was based on an apparent negative relationship between mass-specific metabolic rate and lifespan in endotherms. This hypothesis in its original form has not withstood additional tests and comparisons between the two main lineages of endotherms-birds and mammals, but there is still much to be discovered of the causative links among rate of oxygen consumption, physiology and life history, particularly in ectothermic reptiles. We present data that show adult short-lived snakes, from naturally occurring ecotypes of garter snakes, have higher mass-specific resting metabolic rates at any given body mass (metabolic intensity) across a series of normal activity temperatures (15-32°C). The short-lived ecotype in this geographic region reaches a larger body size, and has life-history traits that place it at the fast end of a pace-of-life continuum (fast growth, early maturation, high reproductive output) relative to individuals of the small-bodied long-lived ecotype. The difference between ecotypes in metabolic intensity, even after acclimation to identical conditions, may reflect evolutionary divergence and genetic differences between ecotypes. The difference in metabolic intensity is not, however, present at birth, so an alternative is that developmental environment may permanently influence metabolic rate and life history. Such developmental canalization could lead to altered gene expression via environmental influences on the epigenome and result in altered metabolic trajectories in the snakes' natural habitats.