Category: Reptiles

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INHS PaCE Lab at Turtle Survival Alliance Symposium

Three members of the INHS PaCE Lab, Dr. Michael Dreslik, Emily Asche, and Claire Dietrich, attended the 23rd Annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles, held in Chattanooga, TN July 20-25, 2025.

Emily Asche presented a paper “Assessing Population Structure and Conservation Priorities for the Western Pond Turtle (Actinemys spp.) on California Military Installations.” The paper was co-authored with Matthew Parry, Michael Dreslik, Robert Lovich, and Thomas Akre.

Abstract: The Western Pond Turtle (Actinemys spp.) is currently under review for listing as a Threatened species under the Endangered Species Act. Widespread population declines driven by habitat loss, predation, and shell disease have led to its designation as a Species of Special Concern in California, sensitive/critical in Oregon, and endangered in Washington. Despite regional protection, federal listing remains uncertain, emphasizing the urgent need for data to guide conservation. To address critical knowledge gaps, we conducted a two-year demographic study across 13 military installations spanning the species’ California range. Standardized week-long trapping sessions yielding data on body size, life stage, and sex. The metrics were used to estimate local abundance to establish a baseline to inform population health and trajectory. Our analysis revealed variations in demographic composition, site-specific abundance, and growth dynamics across installations, identifying high-risk populations and areas with potential recovery. Our findings are essential for prioritizing conservation actions, informing management of military lands, and contributing to range-wide assessments necessary for the species’ recovery planning.

Claire Dietrich presented a poster “Initial Survey of Freshwater Turtle Assemblages at Thirteen Nature Preserves in Northeastern Illinois.” The poster was co-authored with Michael Dreslik.

Abstract: Urbanization of the Chicago metropolitan area has drastically altered the landscape of northeastern Illinois over the past two centuries. Once dominated by forest and marshy wetlands, the region is now characterized by dense urban centers highly fragmented by several major roadways. The resulting loss of natural habitat has impacted regional abundances of some turtle species, such as the state-endangered Blanding’s Turtle (Emydoidea blandingii). Despite modern environmental protections, fragmentation and degradation of the remaining habitat provide little opportunity for populations to expand or recolonize their former range naturally. We sampled thirteen publicly owned forest preserves, conservation areas, and mitigation sites for aquatic turtles with baited hoop traps to determine species richness, diversity, and evenness of the turtle assemblages. Species richness ranged from 1 to 5, with most assemblages comprising common species considered resilient to anthropogenic disturbance such as the Painted Turtle (Chrysemys picta) and Common Snapping Turtle (Chelydra serpentina). Diversity indices were low overall, ranging from 0 to 1.19, but evenness indices varied from 0.38 to 1. We intend to continually reassess turtle assemblages at the sites on a five-year rotation to gain a long-term temporal understanding of demographic trends.

Dr. Dreslik presented a paper “Population Ecology of Spotted Turtles (Clemmys guttata) in Two Isolated Illinois Wetlands,” co-authored with Devin Edmonds, Rose Arnold, and Ethan Kessler.

Abstract: Over sixty percent of evaluated freshwater turtle species are assessed as at risk of extinction by the IUCN Red List. Overexploitation is the greatest threat, with habitat degradation, urbanization, pollution, and the ongoing effects of climate change also having large impacts. Consequently, many freshwater turtle populations are small, isolated, and declining, as is the case for the Spotted turtle (Clemmys guttata). The species has declined across its range in the eastern U.S., with only two populations remaining in Illinois at the western edge of its distribution. We conducted long-term capture-mark-recapture surveys and leveraged data collected over three decades to create demographic models of growth, survival, and reproductive output formulated into an integral projection model framework. The framework evaluates the probability of population persistence and how changes in vital rates affect population growth. Our results show the benefits of integrating size-based data sources for population assessments and the value of long-term monitoring, with implications for improving conservation efforts for Spotted Turtles in Illinois and throughout their range.

 

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PaCE Lab at 2025 Joint Meeting of Ichthyologists and Herpetologists

three people in front of a banner
Chitra Basyal, Rose Arnold, and Joey Cannizzaro at JMIH 2025

It’s herpetology conference season. This past week the PaCE Lab was well represented at the 2025 Joint Meeting of Ichthyologists and Herpetologists, held in St Paul Minnesota July 9-13.

Graduate students Rose Arnold, Chitra Basyal, and Joey Cannizzaro captivated audiences with their papers and oral presentations.

woman presenting scientific poster
Rose Arnold presenting at JMIH 2025

Rose Arnold presented a poster “Gauging Population Health in Urbanized Landscapes: A Body Condition Comparison of Illinois’ Remaining Spotted Turtle (Clemmys guttata) Populations.” Abstract: Urbanization has altered the hydrology and vegetation structure of many remaining wetlands in the United States. Hydrological and vegetation shifts can alter food availability and disrupt food chains, thus impairing energy flow among trophic levels. For wetland species to persist in altered habitats, managers should promptly develop strategies prioritizing the most vulnerable populations. In some cases, land managers must evaluate population health using short-term data, which can be difficult with long-lived turtle species due to extreme longevity and delayed sexual maturity. Body condition indices (BCI) are commonly used as proxy measurements of body fat, which are assumed to reflect foraging success and fitness of individuals. Body condition can change rapidly in response to resource availability, disease, and stress, making it a viable surrogate for assessing short-term population health. A population with significantly lower body conditions may indicate chronic stressors or fewer site resources. The two extant Spotted Turtle (Clemmys guttata) populations in Illinois inhabit sites within a heavily urbanized landscape and previous studies revealed differences in demography and microhabitat composition. Here, we compare body conditions between the two remaining populations of Spotted Turtles in Illinois as an additional measure of population health.

Chitra Basyal presenting at JMIH 2025

Chitra Basyal presented a talk “Structure of freshwater turtle assemblages in a highly developed ecosystem.” Abstract: Freshwater turtles play essential ecological roles in wetlands as omnivores, scavengers, food sources, and nutrient recyclers. Studying freshwater turtle assemblages is crucial because they are sentinel species when monitoring biodiversity and ecosystem health. Northern Illinois has undergone significant habitat modifications due to urbanization, agricultural expansion, and wetland loss, negatively impacting turtle populations. However, most studies in northern Illinois have primarily examined specific species rather than entire turtle assemblages. Our study aims to address the existing gap by investigating freshwater turtle assemblages across five urbanized sites in Illinois. Monitoring the sites used capture-mark-recapture surveys over an extended period; thus, we can assess species diversity, evenness, relative abundance, and richness across sites and years. Our research will determine if there are spatial and temporal variations in assemblage structure, highlight vulnerable species, and provide valuable insights into wetland health in northern Illinois.

person explaining poster to another person
Joey Cannizzaro presenting at JMIH 2025

Joseph Cannizzaro presented a poster “Effects of Vegetation Management on Predation Rates in the Eastern Massasauga Rattlesnake (Sistrurus catenatus). Abstract: Managing habitat to maximize survivorship and population growth is integral to recovering endangered species. Nearly all native tallgrass prairie habitats in the midwestern United States have been anthropogenically converted to agriculture. The decline in remaining habitat due to encroaching woody vegetation and invasive plants impacts many prairie obligate species, including the Eastern Massasauga (Sistrurus catenatus). Eastern Massasaugas requires open habitats and early successional vegetative assemblages to thermoregulate, forage, and reproduce. To reverse declines, many wildlife managers employ vegetative control practices, such as mechanical mowing and prescribed burns, to maintain early seral stages. However, conflicting evidence suggests reducing vegetative cover could lead to artificially higher or lower predation rates. We investigated the effect of early successional vegetation management on the predation rates of Eastern Massasaugas by conducting a clay model predation study. We placed models into two treatments, habitat recently managed for vegetative succession or adjacent unmanaged habitat, and scored them for predation marks. Additionally, clay models were made in two different body postures, outstretched and coiled, to investigate how body posture potentially influences snake predation rates. Our study presents the impact of recent vegetation management on predation rates and provides insights to inform future conservation efforts.

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INHS PaCELab at 2024 Turtle Survival Alliance Symposium

This year’s Turtle Survival Alliance conference was held in Tucson Arizona 2024  July 25-28. Several members of the INHS PaCE Lab presented posters and talks, which we’re excited to share with you.
 
Dr. Dreslik gave a featured presentation during the plenary session,
“Freshwater Turtle and Tortoise Growth: What we know and where to go”
co-authored with Drs Lovich (USGS) and Congdon (Savannah River Ecology Lab).

Dr Dreslik at podiumGrowth is a fundamental life history trait expressed as shape, rate, and size at specific times for individuals in a population. Because energy allocated to competing life demands shifts, all expressions have impactful relationships with other life-history traits. In general, the overall growth pattern of turtles is well understood, but representative studies are decidedly lacking for many species and populations. Additionally, we are building a stronger foundation of the drivers and their consequences on growth; few studies have had the luxury of serially examining populations to determine environmental and habitat related effects. Herein, we present the state of knowledge on growth in freshwater turtles, covering aspects such as pattern, seasonality, determinism, dimorphism, extrinsic drivers, maternal effects, and individuality. Finally, we will provide insight into current analytical advances and direction for future work.

Graduate student Nicholas Dunham presented a poster
“Spatial Ecology of Blanding’s Turtles (Emydoidea blandingii) in an Agricultural Landscape in Northeast Illinois”
co-authored with Ethan Kessler, John Crawford and Michael Dreslik.
Agriculture in Illinois dominates the landscape, leading to widespread alteration of terrestrial and aquatic ecosystems. Much of Illinois’ freshwater wetlands have been heavily channelized and converted into vast networks of ditches in agricultural drainage systems. Thus, these agricultural ditches may represent some of the only available wetland habitats for turtles. A small population of Blanding’s Turtles (Emydoidea blandingii) was discovered living in an agricultural ditch system in Kankakee and Iroquois counties of Northeast Illinois. Blanding’s Turtles use terrestrial and aquatic habitats throughout the season, increasing their mortality risks from farming equipment. To better understand how Blanding’s Turtles utilize an agricultural landscape, we trapped and used VHF radio-telemetry to track 15 individuals (9 females, 6 males) from April to November 2023, totaling 533 locations. Our objectives were to investigate home range sizes, movement rates, and macrohabitat and microhabitat selection by sex and season. The results of our study are preliminary, and data collection will continue from 2024 to 2025. Our results can aid the management of Blanding’s turtles in agricultural-dominated landscapes.
Graduate student Emily Asche presented
“Population Structure of the Declining Western Pond Turtle (Actinemys spp.) Across Thirteen Military Installations in California”
co-authored with Matthew Parry, Thomas Akre, Robert Lovich, and Michael Dreslik.
The Western Pond Turtle (Actinemys spp.) is currently undergoing assessment to be listed as a Threatened species under the Endangered Species Act. It is designated as a species of special concern in California, sensitive/critical in Oregon, and endangered in Washington, indicating an imminent likelihood of listing. Habitat loss, predation, and shell disease have caused significant population declines, yet there remains a scarcity of data necessary for informed management decisions. Understanding the existing population structure of remaining populations is pivotal for initiating effective conservation strategies. We are gathering demographic data from thirteen military installations across their California range to assess the level of concern and identify key management priorities. Data collection spans two seasons, with sampling conducted in week- long intervals using 50 aquatic traps per base, supplemented by relevant data from prior or concurrent studies at each installation. Recorded parameters include body size, life stage, and sex of all individuals to characterize the population structure. Additionally, growth rate and recruitment will be derived from the final dataset. Our study’s objective is to delineate targeted conservation efforts for species recovery.
Rose Arnold presented
“Development of a Detection Model of the Blanding’s Turtle (Emydoidea blandingii) to Guide Conservation Prioritization in Illinois”
co-authored with Michael Dreslik
Woman presenting at podiumLike many turtle species, Blanding’s Turtle (Emydoidea blandingii) populations are declining range-wide due to the synergistic effects of habitat fragmentation, loss, and degradation. In Illinois, Blanding’s Turtle populations are isolated within urbanized or agricultural landscapes, thus hindering migration. Additionally, the status of the species at many historical locations remains unknown, whereby many populations may already be functionally extirpated. Thus, determining the status of populations in Illinois is the paramount conservation priority. Surveys for Blanding’s Turtles require a substantial investment of resources (time, funds, and effort) through trapping and visual searches. Currently, there are few tools for quantitatively determining the effort needed to confirm site occupancy. Here, we construct a detection probability model considering temporal, effort, habitat, weather, and environmental variables. The model will allow surveyors to calculate how much effort is necessary to determine occupancy status for a given site under a given set of conditions. The findings from the initial model sets suggest temporal factors exert the most influence on detection, particularly when compared to weather. However, even in strong-performing models, predicted detection rates remained low.
Chitra Rehka Basyal presented a poster
“Structure and Health of a Freshwater Turtle Assemblage in a Highly Developed Ecosystem”
co-authored with Michael Dreslik, Ny Aina Tiana Rakotoarisoa, Laura Adamovicz, and Matthew Allender
Turtles have important ecological roles in wetlands as omnivores, scavengers, food sources, and nutrient recyclers. Despite such importance globally, their populations are declining, with the proliferation of infectious diseases emerging as a major threat. Our study aims to assess turtle’s community structure and evaluate the physical health of those turtle individuals. We began a turtle capture-mark-recapture survey at a university wetland to study assemblage, composition and individual health. In our first year (2023), we captured 39 turtles of 6 species. Based on the species composition, our study suggests the site may be used for illegal pet releases. We screened 37 individuals for adenovirus, herpesvirus, ranavirus, and mycoplasma using conventional and quantitative PCR. Two species (Painted Turtle [Chrysemys picta] and Red-eared Slider [Trachemys scripta elegans]) were adenovirus-positive, with the virus strain being 99% similar to Sulawesi Tortoise adenovirus. No mycoplasma, Ranavirus, or herpesvirus was detected. Moreover, the Red-eared Slider is likely a natural host of Sulawesi Tortoise adenovirus (STAdV-1). The study forms a baseline for long-term demographic monitoring and health assessments of the turtle assemblage.
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New paper on Timber Rattlesnake hibernacula

Timber Rattlesnake at hibernacula

PhD candidate Andrew Jesper has a new paper out today on determining suitable hibernacula for the state threatened Timber Rattlesnake. The initial habitat suitability model was developed based on known hibernacula across the state of Illinois. The model was refined over a series of surveys based on the model and updating the model based on information from the surveys. Habitat suitability models inform land conservation decisions, enabling prioritization of areas most likely to support suitable hibernacula.

ABSTRACT: The dependency on hibernacula for extended periods presents terrestrial reptiles with the challenge of locating thermally adequate hibernacula each winter. Defining the habitat characteristics of hibernacula is crucial for understanding the overwintering requirements and distributions of hibernacula-dependent reptiles, alongside identifying habitats which warrant special conservation concern. Our objectives were to identify the overwintering habitat characteristics of the imperiled timber rattlesnake Crotalus horridus in Illinois, USA, and to determine the distribution of likely hibernacula habitats throughout the state. Due to the initial sparsity of hibernacula records in Illinois, we adopted an iterative habitat suitability modeling process consisting of 3 distinct rounds of Maxent construction and revision. Each round was informed with updated information from model-guided surveys or by building rapport with in-state naturalists and researchers who knew of additional hibernacula locations. We created our final model using 36 hibernacula and identified slope angle (indicative of rock outcrops and shallow soils), topographical position index, forest patch area, and aspect (decomposed into 2 linearized variables: southness and eastness) as important drivers of C. horridus hibernacula habitat in Illinois. Together, the 5 variables and site surveys suggest the suitable overwintering habitat for C. horridus in Illinois is located on south- to southwest-facing outcrops on upper slopes and ridges of larger forest patches. Such habitat is distributed primarily in southern Illinois and throughout the Mississippi River and Illinois River border counties. Our study adds to the current understanding of the species’ overwintering requirements and provides a foundation for future ecological studies, management, and survey efforts throughout Illinois.

Read the full paper in: Jesper, A. C., S.A. Eckert, S.R. Ballard, J.A. Crawford, and M.J. Dreslik. 2024. Distribution and drivers of critical hibernacula for the timber rattlesnake Crotalus horridus in Illinois, USA. Endangered Species Research Volume 53, page 467

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New publication on Timber Rattlesnake movement

PACeLab PhD Candidate Andrew Jesper co-authored a new paper with his undergrad research advisor Scott Eckert at Principia College. Jesper and Eckert radio-tracked 29 individual Crotalus horridus (13 female, 16 male) in Jersey County, Illinois.

On average, males move greater daily distances and occupy larger home ranges than females, particularly during the summer when Timber Rattlesnakes find mates. Females dispersed shorter distances from their hibernacula than males. Several snakes were tracked over multiple years, and returned to their same general range each summer. This site fidelity may limit the success of translocating adult individuals.

 

 

Abstract

Understanding the home range of imperiled reptiles is important to the design of conservation and recovery efforts. Despite numerous home range studies for the Threatened timber rattlesnake (Crotalus horridus), many have limited sample sizes or outdated analytical methods and only a single study has been undertaken in the central midwestern United States. We report on the home range size, site fidelity, and movements of C. horridus in west-central Illinois. Using VHF telemetry, we located 29 C. horridus (13 female, 16 male) over a 5-year period for a total of 51 annual records of the species’ locations and movements. We calculated annual home ranges for each snake per year using 99%, 95%, and 50% isopleths derived from Brownian Bridge utilization distributions (BBMM), and we also report 100% minimum convex polygons to be consistent with older studies. We examined the effects of sex, mass, SVL, and year on home range sizes and reported on movement metrics as well as home range fidelity using both Utilization Distribution Overlap Index (UDOI) and Bhattacharyya’s affinity (BA) statistics. The home range sizes for male and non-gravid C. horridus were 88.72 Ha (CI 63.41–110.03) and 28.06 Ha (CI 17.17–38.96) for 99% BBMM; 55.65 Ha (CI 39.36–71.93) and 17.98 (CI 10.69–25.28) for 95% BBMM; 7.36 Ha (CI 5.08–9.64) and 2.06 Ha (CI 1.26–2.87) for 50% BBMM; and 78.54Ha (CI 47.78–109.30) and 27.96 Ha (CI 7.41–48.51) for MCP. The estimated daily distance traveled was significantly greater for males (mean = 57.25 m/day, CI 49.06–65.43) than females (mean = 27.55 m/day, CI 18.99–36.12), particularly during the summer mating season. Similarly, maximum displacement distances (i.e., maximum straight-line distance) from hibernacula were significantly greater for males (mean = 2.03 km, CI 1.57–2.48) than females (mean = 1.29 km, CI 0.85–1.73], and on average, males were located further from their hibernacula throughout the entirety of their active season. We calculated fidelity to high-use areas using 11 snakes that were tracked over multiple years. The mean BBMM overlap using Bhattacharyya’s affinity (BA) for all snakes at the 99%, 95%, and 50% isopleths was 0.48 (CI 0.40–0.57), 0.40 (0.32–0.49), and 0.07 (0.05–0.10), respectively. The mean BBMM overlap for all snakes using the Utilization Distribution Overlap Index (UDOI) at the 99%, 95%, and 50% isopleths was 0.64 (CI 0.49–0.77), 0.32 (CI 0.21–0.47), and 0.02 (CI 0.01–0.05)), respectively. Our results are largely consistent with those of other studies in terms of the influence of sex on home range size and movements. The species also exhibits strong site fidelity with snakes generally using the same areas each summer, though there is far less overlap in specific (e.g., 50% UDOI) high-use areas, suggesting some plasticity in hunting areas. Particularly interesting was the tendency for snakes to disperse from specific hibernacula in the same general direction to the same general areas. We propose some possible reasons for this dispersal pattern.

Read the full article: Eckert, S.A., Jesper, A.C. Home range, site fidelity, and movements of timber rattlesnakes (Crotalus horridus) in west-central Illinois. Anim Biotelemetry 12, 1 (2024). https://doi.org/10.1186/s40317-023-00357-8

 

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New paper analyzing long term data on Ornate Box Turtle survival

box turtle
Ornate Box Turtle Photo by D. Edmonds

PaCE Lab doctoral candidate Devin Edmonds has a new paper in the journal Wildlife Biology: “Evaluating Population Persistence of Ornate Box Turtles (Terrapene ornata) at the Northeast Edge of their Distribution.”

This work analyzed 34 years of data from one site and 8 years of data from another to estimate female and juvenile survival and population growth over time. Being able to look at a population over a long period of time provides a better understanding of the population. This study also highlighted the need to protect adult female Ornate Box Turtles if the populations are to persist.

This work was co-authored with members of the Wildlife Epidemiology Lab.

 

Abstract: Turtles and tortoises are among the most threatened vertebrate groups. Their life history is characterized by delayed sexual maturity and a long lifespan, making populations susceptible to decline following perturbations. Despite the urgent conservation need, we are missing estimates of basic demographic traits for many species and populations. The ornate box turtle (Terrapene ornata) is a species lacking crucial demographic data. Many populations are isolated in fragmented habitats, especially in the eastern portion of their range. We carried out long-term capture-mark-recapture surveys on two isolated populations in northern Illinois to estimate population vital rates and project population persistence with deterministic stage-based matrix models. Using 34 years of data, we estimated adult female survival = 0.974 (95% CI: 0.946–0.988) and juvenile survival = 0.867 (95% CI: 0.688–0.951) at our most intensively surveyed site. At a second site using 8 years of data, we estimated adult female survival = 0.897 (95% CI: 0.783–0.954) and juvenile survival = 0.844 (95% CI: 0.551–0.960). Despite seemingly high annual survival rates, populations declined under population projections using mean vital rates. Population growth was most sensitive to adult survival, with increasing sensitivity under more pessimistic scenarios. Our results highlight the importance of long-term demographic studies for threatened species and demonstrate protecting adult female ornate box turtles is critical for ensuring populations persist at the northern edge of their distribution.

Read the full paper:

Edmonds, D.,  L. Adamovicz, M. Allender, A. Colton, R. Nyboer, and M. Dreslik. 2023. Evaluating population persistence of ornate box turtles (Terrapene ornata) at the Northeast edge of their distribution. Wildlife Biology 2023:e01183. doi: 10.1002/wlb3.01183

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New paper on more efficiently detecting Kirtland’s Snake

kirtland's snake
Kirtland’s Snake

Recent PaCE Lab graduate Tyler Stewart published a paper on his M.Sc. work creating a species distribution model for the rare and cryptic Kirtland’s Snake, Clonophis kirtlandii. He found that surveys Mid-May to early July when there was high cloud cover, moderate air temperature, and low relative humidity enhanced the detection probability of this species.

 

Abstract

Snakes are difficult to study due to their cryptic coloration, minimal movements, and use of inaccessible habitats. Although well‐timed surveys during a species’ active season can result in higher detection rates and conserve survey resources (i.e., time and money), survey effort may not ensure the detection of rare and cryptic species. Thus, in such instances, a strategic species‐ specific sampling design is needed. The Kirtland’s snake (Clonophis kirtlandii) is a rare, cryptic species assumed to be experiencing range‐wide declines. Naturalists have noted the disappearance of Kirtland’s snakes from various habitats since the early 1970s. The primary objective of our study was to determine detection of Kirtland’s snakes and the environmental and temporal factors influencing detection. We calculated the effort needed to detect individuals at sites by estimating detection probabilities of 3 known Kirtland’s snake populations in Illinois from 2019 to 2021. Based on 77 Kirtland’s snake detections over 226 site visits (34.1%) across 3 study sites, we found that high cloud cover, moderate air temperature, and low relative humidity enhanced the detection probability of this species. The middle of May to the beginning of July was the best time to conduct surveys when detection rates were highest. As our results suggested, it is imperative to establish strategic monitoring programs maximizing conservation resources to document populations for conservation action and range shifts for species of conservation concern, such as Kirtland’s snakes.

Stewart, T. A., A.R. Kuhns, C.A. Phillips, J.A. Crawford, and M.J. Dreslik.  2023. Estimating the effort required to detect Kirtland’s snakes (Clonophis kirtlandii). Wildlife Society Bulletin. http://doi.org/10.1002/wsb.1498

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New paper on timing prescribed fires to avoid Ornate Box Turtle mortality

Ornate Box Turtle photo by D. Edmonds

PhD candidate Devin Edmonds is lead author on a paper published this week in Journal of Wildlife Management. Recognizing the importance of fire for prairie management, Edmonds et al. examined the behavior and physiology of Ornate Box Turtles to predict when turtles would be underground, sheltered from fire.

 

Abstract

Fire is a vital management tool for maintaining prairie ecosystems. Prescribed burns control invasive species, regulate succession, stimulate plant growth, and are a cheap and effective method for removing excess biomass; however, fire can also inadvertently cause wildlife mortality, placing land managers in a challenging situation. Turtles are especially at risk of mortality from fire because of their low mobility and population sensitivity to reductions in adult survival. We studied ornate box turtles (Terrapene ornata) at 3 sites in Illinois, USA, from 2019–2022 to determine the best predictors of above-ground activity so land managers can conduct prescribed burns when turtles are underground. We used turtle shell temperature, air temperature, soil temperature, and precipitation data to develop a predictive model of above-ground activity. The best model for predicting above-ground activity included an interaction between day of year and current air temperature. Earlier in spring and later in fall, above-ground activity is more likely at higher air temperatures compared to later in spring and earlier in fall when the same likelihood of above-ground activity is predicted at lower air temperatures. In spring, we recommend burning in Illinois ornate box turtle habitat before 1 April when air temperature is <10°C and in fall after 1 November when air temperature is <15°C. Above these temperature thresholds, there is a >5% likelihood that turtles in northern populations are above ground.

Read the full paper:

Edmonds, D. A., Bach, E. M., Colton, A. L., Jaquet, I. S., Kessler, E. J., and Dreslik, M. J.. 2023. Avoiding mortality: timing prescribed burns in ornate box turtle habitat. Journal of Wildlife Management e22510. https://doi.org/10.1002/jwmg.22510

Read more from Elizabeth Bach and Devin Edmonds on the Grassland Restoration Network blog: Ornate box turtle emergence

 

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New paper on Alligator Snapping Turtle movement by ARC program leader Ethan Kessler

Translocated Alligator Snapping Turtle with radio transmitter attached

A paper just out this week  in the Journal of Wildlife Management, “Movement behavior and passive dispersal of a reintroduced population of alligator snapping turtles” found that translocated AST behaved similarly to wild populations, and is largely passive. This can have conservation implications as reintroduced animals may be transported downstream by high flows.

 

Abstract

Maladaptive movement behavior is a leading cause of failure for reptile reintroductions, thus characterizing movement for translocated populations is important to project success. From 2014–2016 we radio-tracked 183 immature reintroduced alligator snapping turtles (Macrochelys temminckii) using very high frequency telemetry in a stream in southern Illinois, USA. We assessed environmental, temporal, morphometric, and microhabitat factors influencing movement, including post-release dispersal from reintroduction sites, movement probability, and step length. We used directional statistics to investigate the effects of precipitation and age on directional movement in the stream. Numerous factors influenced active movement, including ambient temperatures, time since release, use of log jams, turtle size, and age. Precipitation had an age-biased effect on movement. Directional analyses suggested that movement was largely passive as turtles were swept downstream with increased discharge. Overall, the behavior of reintroduced alligator snapping turtles was similar to that reported in wild populations. Passive downstream transport has implications for reintroduced and natural populations as a force for unintentional emigration in channelized streams under current conditions and future high flow regimes.

Read the full paper here.

Kessler, Ethan J. and Michael J. Dreslik. 2023. Movement behavior and passive dispersal of a reintroduced population of alligator snapping turtles. Journal of Wildlife Management. https://doi.org/10.1002/jwmg.22511