Association of size, climatic factors, and mercury body burdens with movement behavior in American alligators

Animal movement behavior provides insight into organismal and ecological function. These functions are often disturbed by anthropogenic influences, such as urbanization and habitat fragmentation, yet the effects of long-term exposures to environmental contaminants on movement have yet to be examined. The long lifespans and broad diets of crocodilians often lead to bioaccumulation of persistent contaminants and confer a marked vulnerability to consequent physiological effects. In this study, we investigate the relationships between blood concentrations of mercury (Hg), a widespread contaminant with well characterized neurotoxicity, and movement patterns in free living, naturally exposed American alligators (Alligator mississippiensis). We sampled adult male alligators from two former nuclear cooling reservoirs with different Hg contamination histories and placed GPS transmitters on a subset of individuals from each reservoir (13 total). Data collected over the ensuing two years were analyzed using a linear mixed effects framework combined with AICc model selection to resolve the relationships linking seasonal alligator movement (daily activity (s) and daily distance (m)) and home range to climate conditions, individual traits, and blood Hg concentrations (mg/kg; wet weight). We found that climate conditions, alligator size (snout-vent-length), and blood Hg concentrations all influence alligator daily activity but do not contribute to alligator daily movement (distance). Furthermore, we found that blood Hg concentrations were strongly correlated with seasonal home range size where individuals with elevated Hg had larger home ranges in spring, fall, and winter. These findings provide insight into how climate, anthropogenic contaminants, and individual traits relate to alligator movement patterns across seasons.

Effects of ophidiomycosis on movement, survival, and reproduction of eastern foxsnakes (Pantherophis vulpinus)

Ophidiomycosis (snake fungal disease) is caused by the fungal pathogen Ophidiomyces ophidiicola, which causes dermal lesions, occasional systemic infections, and in some cases, mortality. To better understand potential conservation implications of ophidiomycosis (i.e., population-level effects), we investigated its impacts on individual fitness in a population of endangered eastern foxsnakes (Pantherophis vulpinus). We tracked 38 foxsnakes over 6 years and quantified body condition, movement patterns, oviposition rates, and survival. Body condition, distance travelled, and oviposition rates were similar between snakes with and without ophidiomycosis. Interestingly, snakes that tested positive for the pathogen travelled farther, suggesting that movement through a greater diversity of habitats increases risk of exposure. Ophidiomycosis did not negatively affect survival, and most apparently infected snakes persisted in a manner comparable to snakes without ophidiomycosis. Only one mortality was directly attributed to ophidiomycosis, although infected snakes were overrepresented in a sample of snakes killed by predators. Overall, our results suggest that ophidiomycosis may have sublethal effects on eastern foxsnakes, but do not suggest direct effects on survival, ovipositioning, or viability of the study population.

The Association Between Ambient Temperature and Snakebite in Georgia, USA: A Case-Crossover Study

The World Health Organization has identified snakebite envenoming as a highest priority neglected tropical disease, yet there is a dearth of epidemiologic research on environmental risk factors, including outdoor temperature. Temperature may affect snakebites through human behavior or snake behavior; snakes are ectotherms, meaning outdoor temperatures influence their internal body temperature and thus their behavior. Here we investigate the relationship between short-term temperature and snakebites in Georgia, one of the most biodiverse US states in terms of herpetofauna. We acquired emergency department (ED) visit data for Georgia between 1 January 2014 and 31 December 2020. Visits for venomous and non-venomous snakebites were identified using diagnosis codes. For comparison, we also considered visits for non-snake (e.g., insects, spiders, scorpions) envenomation. Daily meteorology from the Daymet 1 km product was linked to patient residential ZIP codes. We applied a case-crossover design to estimate associations of daily maximum temperature and snakebite ED visits. During the 7-year study period, there were 3,908 visits for venomous snakebites, 1,124 visits for non-venomous bites and 65,187 visits for non-snake envenomation. Across the entire period, a 1°C increase in same-day maximum temperature was associated with a 5.6% (95%CI: 4.0-7.3) increase in the odds of venomous snakebite and a 5.8% (95%CI: 3.0-8.8) increase in non-venomous snakebite. Associations were strongest in the spring. We also observed a positive and significant (p < 0.05) association for non-snake envenomation, albeit slightly smaller and more consistent across seasons compared to those for snakebites.

A new tale of lost tails: Correlates of tail breakage in the worm lizard Amphisbaena vermicularis

Predator-prey interactions are important evolutionary drivers of defensive behaviors, but they are usually difficult to record. This lack of data on natural history and ecological interactions of species can be overcome through museum specimens, at least for some reptiles. When facing aggressive interactions, reptile species may exhibit the defensive behavior of autotomy by losing the tail, which is also known as "urotomy". The inspection of preserved specimens for scars of tail breakage can reveal possible ecological and biological correlates of urotomy. Herein, we investigated how the probability of urotomy in the worm lizard Amphisbaena vermicularis is affected by sex, body size, temperature, and precipitation. We found higher chances of urotomy for specimens with larger body size and from localities with warmer temperatures or lower precipitation. There was no difference in urotomy frequency between sexes. Older specimens likely faced - and survived - more predation attempts through their lifetime than smaller ones. Specimens from warmer regions might be more active both below- and aboveground, increasing the odds to encounter predators and hence urotomy. Probability of urotomy decreased with increased precipitation. Possibly, in places with heavier rainfall worm lizards come more frequently to the surface when galleries are filled with rainwater, remaining more exposed to efficient predators, which could result in less survival rates and fewer tailless specimens. This interesting defensive behavior is widespread in squamates, but yet little understood among amphisbaenians. The novel data presented here improve our understanding on the correlates of tail breakage and help us to interpret more tales of lost tails.

Assessing the Increase of Snakebite Incidence in Relationship to Flooding Events

Snakebite envenoming causes up to 138,000 deaths and 400,000 permanently disabled victims worldwide every year. Flooding is one of the many factors that seems to influence the incidence of snakebite. The catastrophic floods from late 2018 in Kerala (India) were widely broadcast and are an example of how flooding events are related to the increased incidence of snakebite. This relationship has been mentioned regularly in scientific and grey literature, but usually quite scarcely in comparison to other topics linked to snakebite. Additionally, web media, mobile communications, and social media have started playing an important role not only in providing access to information on flooding-related snakebite events, but also in snakebite prevention at a larger scale. In order to better understand to what extent the relationship between snakebite incidence and flooding is reported and quantified and appraise the importance of mobile communications and social media in snakebite prevention and management, we performed multiple searches in generic (Google) and specialized (PubMed, Web of Science, Google Scholar) databases. We retrieved 68 scientific articles and 5 reports ranging from 1892 to 2018 mentioning or analyzing flooding and the increased incidence of snakebite. Additionally, we found 68 web media reports linking flooding and snakebite. This review indicates that the increase of snakebite incidence due to flooding has been repeatedly observed all over the world. This phenomenon could be exacerbated because of climate change, which is expected to increase the overall magnitude and frequency of flooding. However, it could also be mitigated by the role the Internet, mobile communications, and social media could play in snakebite prevention and human and animal rescue strategies during flooding.