Herpetology

Contributed Oral

 
Of Predators and Pools: Developmental Differences of Larval Thermal Preference When Exposed to Predators and Shortened Hydroperiods
Cassandra Thompson, Viorel Popescu
Environmental variation during ontogeny can have profound, variable effects on an organism’s phenotype, fitness, morphology, and physiological attributes. Abiotic factors such as temperature regimes and pool drying rates often have negative impacts on the developmental environments of larval amphibians. Additionally, biotic pressures from competitors, food availability, and predation risk can interact to create synergistic, additive, or antagonistic effects on larval development. Across the globe climate change is predicted to affect annual temperatures and precipitation rates, leading to warmer temperatures and drought-like conditions in many areas, leading to shorter hydroperiods of breeding pools and eliciting plastic responses of larval developmental times. This study was designed to evaluate potential effects of hydroperiod length and predation risk of aeshnid odonate larvae on larval wood frogs (Lithobates sylvaticus). To do this, we manipulated hydroperiod lengths in cattle tank mesocosms with and without predation cues (caged odonate larvae).  We assessed the effects of the aquatic treatments on larval growth and development and temperature preference at 3 separate Gosner stages, additionally assessing overall survival to metamorphosis. While we found no significant difference in thermal preference of tadpoles between short and long hydroperiod treatments, tadpoles from predator treatments preferred significantly different temperature regimes compared to those from non-predator treatments. Additionally, the coefficient of variation of preferred temperatures and average shifted throughout developmental stages. Shortened hydroperiods resulted in decreased larval survival and increased developmental rates, leading to smaller sizes at metamorphosis. When combined with predation risk, shortened hydroperiods decreased overall time to metamorphosis (~5-7 days) and illicited greater variation in size at metamorphosis (SVL).
 
Developing an Occupancy Model and Understanding Activity Patterns of Ornate Box Turtle in Eastern New Mexico
Ivana Mali, Thanchira Suriyamongkol, Laramie Mahan, Alissa Kreikemeier, Vinicius Ortega-Berno
The ornate box turtle (Terrapene ornata) is a terrestrial Emydid, listed as near threatened by the IUCN Redlist due to habitat destruction, degradation, habitat fragmentation, commercial harvest, and road mortality. Terrapene ornata is secretive, which can pose a challenge to conducting systematic surveys and assessing species status. Studies on the species’ biology have relied on opportunistic encounters on the road and radiotelemetry. The objective of this study was to assess the feasibility of using transect line surveys to develop a single-season occupancy model for T. ornata in Roosevelt County, New Mexico. We further used radiotelemetry to link turtle activity patterns with environmental conditions to aid in the understanding of species detectability. Our occupancy model showed the influence of individual observers and the time of day on detection probability, by which the detectability of 0.52 (SE = 0.14) was the highest between 0900-1000 h. We found T. ornata to most likely occupy habitats with less dense ground cover while avoiding highly altered habitats (i.e., cultivated fields). Radiotelemetry further revealed the effect of humidity, time of day, and temperature on turtle activity patterns. The lowest activity occurred between 1200–1700 h, whereas peak activity occurred in the early morning hours (0600–0900 h). The peak activity was between ~10–25 C while higher humidity promoted activity. Our study represents the first attempt at using transect line surveys in developing an occupancy model for the ornate box turtles. We suggest that future studies on box turtle occupancy focus on finer-scale habitat assessment such as vegetation, invertebrate, and small mammal surveys.
 
Monitoring Strategies for Repatriated Eastern Indigo Snakes in Southern Alabama
James Godwin, Craig Guyer, Daniel Young, Francesca Erickson, Conor McGowan
The Eastern Indigo Snake (Drymarchon couperi) was extirpated from Alabama in the 1970s and was declared threatened throughout its range under the Endangered Species Act in 1978. In 2010, a repatriation program began in Conecuh National Forest (CNF), and now that ten years have passed since the inception of the program, monitoring of this population is crucial. Monitoring of a population after reintroduction is important in determining population size, survival rates, reproduction and the success of the reintroduction effort. Previous projects in CNF involved radio tracking indigo snakes after release and analyzing release methods, home range, and habitat selection. However, since 2014, monitoring has been restricted in temporal scope and sampling methods.  We evaluated five different monitoring methods: the previous radio tracking data, intensive pedestrian surveys, camera trapping, remote RFID readers and passive box traps. Our objectives were to evaluate multiple monitoring methods with respect to the value of information gathered and monitoring costs, using a Structured Decision Making approach. In 2019, increased pedestrian surveys and box traps successfully yielded an increased magnitude of encounters and captures of released snakes. In 2020 camera traps recorded indigo snakes at multiple gopher tortoise burrows, however individual IDs could not be made. We deployed cameras and a remote RFID PIT tag reader in 2021 by placing antennas around tortoise burrows. This allowed for identification of all PIT-tagged individuals using a burrow, when, and how often. These five methods all show potential for success, but have different costs and quality of gathered information. We evaluated each method by scoring them according to cost, disturbance to snakes, type of data gathered, and quality and utility of data in analysis for occupancy, abundance, and survival estimates. We were then able to make recommendations on the best and most cost-effective methods of monitoring this species and determine how to best make abundance estimates. Additionally, we discuss results of two single-season occupancy analyses of the CNF indigo snake population. 
 
Conservation Action Through Expert Solicitation for Illinois’ Amphibian and Retile Species of Greatest Conservation Need
John Crawford, Christopher Phillips, Andrew Kuhns, Michael Dreslik
In 2000, Congress created the State Wildlife Grant program, whereby states maintain Wildlife Action Plans to address unprecedented extirpation rates and population declines of imperiled fauna. The plans identified sensitive species – termed Species of Greatest Conservation Need (SGCN) – and their primary habitats and threats. However, given the number of species listed and no hierarchical priorities, conservation action has been haphazard and limited. Therefore, we focused on the conservation needs of amphibian and reptile SGCNs in Illinois through focused expert solicitation to ascertain: 1) our current knowledge base; 2) perceived threats; 3) actionable items and synergies. The main goal of our work was to provide a unified course of conservation action.
 
Applying DNA Extracted from Reptile Feces to Diverse Wildlife Investigations
Michael Westphal, Mark Statham, Deborah Woollett
Wildlife biologists are increasingly seeing benefits from gathering DNA from indirect sources (eDNA). We optimized the collection of reptile feces (via scat detection dogs) and the extraction of DNA from those feces in a study targeting the Federally endangered blunt nosed leopard lizard, Gambelia sila.  Because we could not in practice limit the dogs to detecting G. sila alone, we garnished a robust set of genomic data on multiple species that have already proved valuable in diverse lines of research on G. sila as well as other reptiles in its community, including the California whiptail lizard, Aspidocelis tigris; Blaineville’s horned lizard, Phrynosoma blainvillii, and the yellow-backed spiny lizard, Sceloporous uniformis.  Applications include a study of the interactions of lizards with desert shrubs; evidence for decline of G. sila in an isolated preserve, and the discovery of S. uniformis at multple sites where it was not expected. Ongoing projects include comparison of reptile communities between two desert sites as well as population monitoring of G. sila. We discuss the implications for research and conservation worldwide.
 
Assessment of Turtle and Leech Parasite-Host Assemblage Variation in Middle Tennessee Wetlands Across a Disturbance Gradient
Laura Horton, William Sutton
Prior research has established clear links between decreased reptile biodiversity in degraded or disturbed habitats, including chelonian groups. There are negative impacts associated with high parasite loads on hosts, and previous studies found parasite loads increase with habitat disturbance, however there have been no published attempts to evaluate detectable sublethal health effects associated with this potential increase in chelonian ectoparasite (leech) load. Thus we assessed if leech loads varied across a landscape disturbance gradient in Middle Tennessee wetlands and if they follow measurable patterns of increased sublethal health effects on chelonians by assessing heterophil:lymphocyte ratios, packed cell volume, and host body condition. We sampled 19 wetlands from June-October 2018 and obtained data from three host species; Trachemys scripta elegans, Sternotherus odoratus, and Chelydra serpentina. Collectively, the interpretation of these data may be used to understand how anthropogenic disturbance affects wetland turtle-leech communities and potential associated health implications.
 
Influence of Landscape Condition on Relative Abundance and Body Condition of Two Generalist Freshwater Turtle Species
Joel Mota, Danielle Canning, Donald Brown
Anthropogenic land use changes have broad impacts on biological diversity, often resulting in shifts in community composition. While many studies have documented negative impacts on occurrence and abundance of species, less attention has been given to native species that potentially benefit from anthropogenic land use changes. For many species reaching high densities in human-dominated landscapes, it is unclear whether these environments represent higher quality habitat than more natural environments. We examined the influence of landscape ecological integrity on relative abundance and body condition of two native generalist freshwater turtle species that are prevalent in anthropogenic systems, the painted turtle (Chrysemys picta) and red-eared slider (Trachemys scripta elegans) using linear mixed modelling techniques. Painted turtles (n = 625) were sampled at 46 wetlands across 10 counties in West Virginia, and red-eared sliders (n = 715) were sampled at 42 wetlands across 5 counties in Texas. Relative abundance was negatively associated with ecological integrity for both species, but the relationship was not strongly supported for painted turtles. Body condition was positively associated with ecological integrity for painted turtles, with no strong association for red-eared sliders. Our study suggests that both species benefitted at the population level from reduced ecological integrity, but individual-level habitat quality was reduced for painted turtles. The differing responses between these two habitat generalists could partially explain why red-eared sliders have become a widespread exotic invasive species, while painted turtles have not.
 
Ground Cover and Native Ant Predation Influence Survival of Metamorphic Amphibians in a Southeastern Pine Savanna Undergoing Restoration
Angela Burrow, John Maerz, Brian Crawford
Longleaf pine savannas historically supported abundant ground cover maintained by frequent fire but little other disturbance. Ground cover creates microclimates with lower temperatures, higher humidity, and increased soil moisture that may benefit wildlife, particularly small vertebrates such as amphibians. Today, most historical pine savannas have had extensive soil disturbance and altered fire regimes resulting in reduced ground cover and altered soil fauna communities including predatory invertebrates. We used a factorial terrestrial cage study to test the effects of native wiregrass (Aristida spp.) cover and the exclusion of a native predatory ant (Dorymyrmex smithi) on the survival of post metamorphic Ornate chorus frogs (Pseudacris ornata) and Gopher frogs (Rana capito). Although we were unable to achieve full ant exclusion, ant reduction in exclusion treatments and plant cover had an interactive effect on metamorph survival. Ant exclusion tended to increase Gopher frog survival and this effect was more pronounced when wiregrass was present. Within ant treatments, survival of Gopher frogs increased slightly with increasing wiregrass cover. Ornate chorus frogs had a high probability of survival (>95%) in all ant exclusion treatments regardless of wiregrass cover; however, in treatments without ant exclusion, survival increased with increasing wiregrass cover. Our results demonstrate that high abundances of a native ant species and low coverage of native wiregrass, which are legacies of historical soil disturbance and altered fire regimes, interact to elevate mortality of juvenile amphibians. Minimizing soil disturbance and restoring native ground cover are likely important for amphibian habitat management within historical southeastern pine savannas.
 
Chasing Ornate Box Turtle in Southeastern Colorado: A Look at Home Range, Seasonal Movements, and Microhabitat Preferences
Ellen Norton, Franziska Sandmeier, Nate Bickford
Ornate box turtles are an understudied species across most of their range, especially in Colorado. Literature suggests that further understanding of environmental factors as predictors of survival of the ornate box turtle would be beneficial to species survival and a better understanding of this species ecology and population dynamics.This study determined the home range of ornate box turtles and looked at the difference in home range based on sex and size (by carapace length) We also identified how weather and seasonal changes influence an individual turtle’s movement and how vegetation is selected based on thermal qualities. 20 turtles were fitted with Cellular Tracking Technologies (CTT) PowerTag radio transmitters on a bottom marginal scute of the carapace and a small paper identifier number. Weather data was collected by an on-site weather station and compared to NOAA weather data. Turtle temperature models was deployed with a Thermochron iButton® temperature data logger to calculate the average temperature of surrounding microhabitat and placed in-ground around summer burrows to calculate average burrow temperatures. With movement data we calculated home ranged (ADKE) and compared differences based on sex and size. We also compared movement before and after weather to identify weather and seasonal changes impacts movement response. Habitat selection based on thermal quality was analyzed using contingency tests. We identified differences in home ranges and movement patterns after weather events.
 
A Tail of Two Cities: Using Microsatellite DNA to Study Gene-Flow in Post-Dam Populations of Common Side-Blotched Lizards in Grand Canyon National Park
Paul Beier, Gerard Allan, Tessa Corsetti, Jacqueline Lyman, Carol Chambers
The 1963 completion of Glen Canyon Dam in Arizona permanently altered the Colorado River corridor through the Grand Canyon. It created a relatively constant flow rate, much colder temperatures, and no slow moving, warm periods. The dam irreversibly changed the Colorado River and its riparian habitat for many species, and likely made it uncrossable for most. However, the effect of impoundments on rivers, especially on ectothermic reptiles, is understudied. We collected tissue samples from tail clips from common side-blotched lizards (Uta stansburiana) using dental floss lizard lassos. Our design included adequate replication by sampling at two widely separated sites in Grand Canyon National Park and one reference site that mimicked pre-dam conditions above Glen Canyon Dam in Cataract Canyon, Canyonlands National Park. We examined 9 microsatellite loci to determine if changes in river flow and temperature caused by the Glen Canyon Dam reduced gene flow across the Colorado River for this native reptile. Preliminary results show detectable variability in genotypes of each lizard population. Additionally, we have generated genetic data for ~ 200 common side-blotched lizards, a previously understudied species with minimal genetic information. These results support our hypothesis that the new colder, high-flow river presents a significant barrier for terrestrial vertebrates along the Colorado river. This work contributes to the understanding of the impact of human ecosystem manipulation on terrestrial vertebrates and will positively influence how riverine systems and reptiles are managed. 

Contributed Oral
Location: Virtual Date: November 4, 2021 Time: 4:00 pm - 5:00 pm