Growth 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.
The Autecology of a Male Eastern Massasauga
Click the animated gif above to enlarge and view slide show
Three new species of Mantellid frog from Madagascar
Three new species of frogs from Madagascar were described in a paper co-authored by PACE Lab PhD candidate Devin Edmonds, led by researchers at Zoological Institute at Technische Universitat Braunschweig.
The group of frogs, Genus Guibemantis, subgenus Pandanusicola, spend their lives in the Pandanus (screw-pine) trees, which are common in the Andasibe area of Madagascar. They live and reproduce in water that pools in the leaves of the trees. While surveying the trees, the researches observed frogs that did not look like any known species Genetic testing revealed 4 new species for the region, 3 of which were new to science.
Read an article in the Miami Herald
Read the full paper at
Hugh Gabriel, Laila-Denise Rothe, Jörn Köhler, Sandratra Rakotomanga, Devin Edmonds, Pedro Galán, Frank Glaw, Richard M. Lehtinen, Andolalao Rakotoarison and Miguel Vences. 2024. Unexpected Diversity and Co-occurrence of phytotelmic Frogs (Guibemantis) around Andasibe, one of the most intensively surveyed Amphibian Hotspots of Madagascar, and Descriptions of Three New Species. Zootaxa. 5397(4); 451-485. DOI: 10.11646/zootaxa.5397.4.1
New paper analyzing long term data on Ornate Box Turtle survival
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:
New paper on more efficiently detecting 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
INHS PaCE Lab members present at The Wildlife Society meeting
Two members of the INHS PaCE Lab presented at The Wildlife Society annual conference November 5-9 in Louisville, KY.
UBAP program leader and ornithologist Anastasia Rahlin presented a poster “Using Point of Care devices to assess Marsh and Sedge Wren food limitation”
Abstract:
Food limitation affects wildlife health and survival, may stem from differences in body condition or habitat quality between sites, and may be exacerbated by extreme weather events. Blood metabolites have previously been used as a food limitation index in birds. To assess changes in blood metabolites in marsh and sedge wrens, we used Point of Care devices to measure blood glucose, ketones, and triglyceride levels as short and long-term food limitation indices. We collected blood samples from wrens in May-August 2022 and 2023 in two Illinois DNR state parks and one dedicated conservation area in the Chicagoland Wilderness region over the duration of the breeding season. Our data indicate short-term food limitation may increase as the breeding season progresses for both Marsh and Sedge Wrens. Ongoing modeling will test whether body condition (age, fat and muscle scores), habitat quality (wetland extent and composition), or extreme weather (drought or flooding) best predicts glucose, ketone, and triglyceride levels over the course of the breeding season. Our findings will provide insights into physiological responses of sedge and marsh wrens to food limitations, and highlight the utility of using POC devices to rapidly measure blood metabolites in the field with minimal impacts to study species. An additional goal of this research is to use blood metabolite data to identify high-quality sites for migratory birds; our data will be used to evaluate the effectiveness of conservation areas at providing high-quality habitat. This work will inform wetland and wet meadow management strategies for migratory birds.
Abstract:
Forested ephemeral wetlands (FEW) support diverse communities of habitat specialist species across the eastern United States, including wetland-breeding amphibians (WBA). Due to their reliance upon FEW for breeding habitat, the location of FEW on the landscape influences population dynamics and distribution of WBA. Generally, FEW are difficult to detect due to their small size and position under the canopy, however, recent technological advances provide the ability to remotely detect FEW with great accuracy. Improved FEW detection methods enable a better understanding of how FEW characteristics and distribution influence WBA presence and abundance. We counted egg masses of two widespread WBA species, Spotted Salamanders and Wood Frogs, at 231 FEW on public lands in southern Illinois using a double observer methodology from 2020–2023. We then used local and landscape characteristics to predict egg mass abundance for each species. We found egg mass counts were highly correlated between observers for each species, but the presence and abundance of egg masses were not highly correlated between the two species. For Spotted Salamanders, we found a positive effect of wetland size on egg mass abundance but found no effect of canopy cover within a 200 m buffer. Conversely, for Wood Frogs we found no effect of wetland size, but egg mass abundance was positively associated with canopy cover within 200 m of FEW. Results from this study will provide a foundation for the estimation of WBA across broad geographic scales using discrete maps of FEW.
New paper on Baron’s mantella frog, co-authored by Devin Edmonds
INHS PaCE Lab PhD candidate Devin Edmonds co-authored a recent paper on habitat features of Baron’s Mantella Frog. Tantely Rasoarimanana (Université d’Antananarivo) and Olivier Marquis (Paris Zoo) led the collaboration with the NGO Man and the Environment. The study aimed to identify what microhabitat features explain the presence of Baron’s mantella frog (Mantella baroni) and also estimate their population sizes in Vohimana Reserve, eastern Madagascar. We found that leaf litter depth and the number of small trees in a quadrat were important habitat features; deeper leaf litter and fewer small trees explained if M. baroni was present.
New paper on timing prescribed fires to avoid Ornate Box Turtle mortality
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
New paper on Alligator Snapping Turtle movement by ARC program leader Ethan Kessler
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.
New publication from aquatic ecologist Hugo Ruellen
INHS PaCE Lab’s aquatic ecologist, Hugo Ruellen is lead author on a recent publication stemming from his M.Sc. research on freshwater mussels: “Predicting suitable habitat for surrogate species of critically imperiled freshwater mussels to aid in translocations.”
Mussel translocations have been used to mitigate the impacts of in-stream construction projects, including bridge replacements. This work developed a model to predict suitable habitat for mussels. “Knowing where and how much suitable habitat is present in rivers is essential to the conservation and long-term persistence of endangered freshwater mussel species, and habitat suitability models such as these are important tools for achieving these goals.”
Ruellan, Hugo Y., Kirk W. Stodola, Alison P. Stodola, and Jeremy S. Tiemann. 2023. Predicting suitable habitat for surrogate species of critically imperiled freshwater mussels to aid in translocations. Freshwater Science 42(3): 296-314. https://doi.org/10.1086/726740