Amphibian populations, including those of lungless salamanders (Plethodontidae), are susceptible to population declines, especially considering current and predicted climate change. Like many organisms, plethodontid salamanders exhibit reproductive plasticity to maximize population growth in response to environmental conditions. A better understanding of the external causes of reproductive plasticity can provide more accurate population models through the explicit incorporation of such drivers. To this end, we sampled Southern Pygmy Salamanders (Desmognathus wrighti) along a 1345-m elevational gradient in Great Smoky Mountains National Park, USA, to determine the effects of body size and elevation on reproductive investment. Using Bayesian mixed effects models, we assessed whether body size, elevation, or a combination of these factors best explained the probability an individual was gravid, the number of ova in gravid females, and the number of testis lobes in mature males. We found that the interaction of body size and elevation best explained each reproductive measure. Larger females were generally more likely to be gravid, with annual reproduction in fully mature females at low to mid-elevations and roughly biennial reproduction at high elevations. We also found a positive relationship between body size and ova counts at low and mid-elevations, but despite a reduction in reproductive frequency at higher elevations, we found no effect of body size on ova count. In addition, the addition of testis lobes, which has commonly been used as a proxy of age in plethodontid salamanders, occurred at larger body sizes with increasing elevation. Our findings support previous work showing a relationship between body size and reproductive ecology in desmognathine salamanders while providing insight into the complexity of this relationship in the context of elevational clines. Reproductive ecology significantly influences population dynamics; thus, further refinement of these observed patterns and their underlying causes is necessary to advance plethodontid salamander population ecology.

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.

With the conservation status of Macrochelys (alligator snapping turtles) being examined at the national level, our objective was to compile categorical data on threats from anthropogenic interactions. We included information from (1) author-collected anecdotes on human-turtle interactions and (2) radiographs to assess the prevalence of ingested fishing hooks. We placed 173 interactions involving 192 incidents into 9 IUCN threat categories and found bycatch involving fish hooks to be 4 times more numerous than the second-most numerous threat, turtle persecution. Fishing bycatch resulted in a high proportion of turtle mortalities (39%), and bycatch incidents in several cases preceded the highest-mortality threat (53%), persecution of individuals involving shooting or blunt trauma. We recommend fishing bycatch-mitigation measures and educational efforts to help conserve Macrochelys.

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.

Herein we briefly provide a background context for and summary overview of the articles comprising this special issue of the Southeastern Naturalist on Macrochelys spp. (alligator snapping turtles). We also make a case for standardization in collecting and reporting morphometric data on these species, clarify the current taxonomic status within the genus, provide updated information on the distribution of Macrochelys in the US, and include a current bibliography and categorical analysis over time of the rapidly growing collection of literature focused on these iconic turtles.

Understanding feeding performance can inform feeding ecology and niche dynamics. Macrochelys temminckii (Alligator Snapping Turtle) and Chelydra serpentina (Common Snapping Turtle) are closely related, sympatric species with documented interactions. To understand ontogenetic and interspecific differences in bite performance, we measured bite force in an ontogenetic series of 62 Alligator Snapping Turtles and 33 Common Snapping Turtles. Within species, bite force positively correlated with size but scaled differently by species. Alligator Snapping Turtles produced higher maximum bite forces overall throughout ontogeny than Common Snapping Turtles, although Alligator Snapping Turtles reach significantly larger maximum sizes than Common Snapping Turtles, thereby enabling them to produce higher maximum bite forces. Differences in bite force between these species provide biomechanical context for distinctions in the ecologies of both species.

The lingual lures of Macrochelys (alligator snapping turtles) are believed to be the only prey-capturing lures within the mouths of modern reptiles. To date, no formal assessment of lure condition in Macrochelys has been published, and few researchers record lure data. Herein, we report damaged or missing lures from 25 Macrochelys temminckii (Alligator Snapping Turtle; 7 adults, 18 juveniles) from a sample of more than 2000 lure assessments in 4 states, indicating this is a rare occurrence. We also describe lingual lure color observed in these assessments and introduce standardized terminology and color categories. We suggest researchers record data on the condition and coloration of the lingual lure to further our understanding of this ecological and evolutionary adaptation.

Few studies have characterized the prevalence of intraerythrocytic parasites in free-ranging chelonian populations or their occurrence across habitats. It is hypothesized that chelonians in different habitats have different exposures to vectors and thus differences in hemoparasite presence. This study explored the prevalence and intensity of intraerythrocytic parasites by examining blood smears from four species of Illinois turtles: wild Blanding's turtle (Emydoidea blandingii), eastern box turtle (Terrapene carolina carolina), ornate box turtle (Terrapene ornata ornata), and prerelease head-started alligator snapping turtle (Macrochelys temminckii). Intraerythrocytic parasites were identified in all examined species except for the alligator snapping turtle. For all age classes, Blanding's turtles had both the highest prevalence of hemoparasites and the highest intensity of infection of all sampled species, whereas adult Blanding's turtles had a significantly higher prevalence than juveniles (P < 0.05). Because this is the first study of hemoparasites in Illinois chelonians, further research is needed to identify the specific species of intraerythrocytic parasite, the potential vectors, and the effect that these hemoparasites have on the health of chelonians.

The alligator snapping turtle (Macrochelys temminckii) is the largest freshwater turtle species in North America and is classified as state endangered in Illinois. Head start programs that include health assessments and pathogen detection are being conducted to restore this species to its historic range. Physical examinations and oral and cloacal swabs were collected from 97 head start alligator snapping turtles prerelease and from 58 recaptured turtles postrelease in 2014. Conventional polymerase chain reaction and sequencing targeting the RNA polymerase beta subunit gene and the 16S-23S ribosomal RNA intergenic spacer detected a single prerelease individual with Mycoplasma sp. with closest relation to Mycoplasma spp. of other freshwater turtles. This individual did not display any clinical signs at the time of release or sampling. Mycoplasmosis has been characterized as a disease of conservation concern in tortoises and may represent a threat to small and fragmented chelonian populations. Findings of this study indicate that Mycoplasma sp. DNA is present in an Illinois alligator snapping turtle, and future investigation into the impact of this infection may support conservation efforts.

Herpesviruses are significant pathogens of captive-reared and free-ranging chelonians worldwide. Lesions associated with chelonian herpesvirus infection are species dependent and include stomatitis in tortoises, hepatic necrosis in pond turtles, and fibropapillomas in sea turtles, among other conditions. Herpesviruses also have been detected in several free-ranging freshwater turtle species with no clinical signs of illness at a prevalence from 2 to 56%. The alligator snapping turtle (Macrochelys temminckii) is a freshwater turtle species endemic to the United States that has experienced declines throughout its range. Reintroduction of this species is currently underway in several states. As part of a health surveillance program, in concert with reintroduction efforts, we investigated the presence of herpesvirus in captive and free-ranging alligator snapping turtles. Using conventional consensus polymerase chain reaction, we tested combined oral/cloacal swab DNA samples (n = 197) from head-started alligator snapping turtles prerelease and postrelease in southern Illinois (n = 153), prerelease samples from adult turtles confiscated from Florida (n = 18), and prerelease samples from captive-reared individuals from northern Louisiana (n = 26). Herpesvirus DNA was not detected in any sample. Possible explanations for these results include lack of exposure, latency in tissues not sampled, and viral quantities below the level of detection of the assay. Continued surveillance for this and other pathogens is helpful in characterizing potential disease risks from captive-reared reintroduction programs and will enhance future conservation efforts of this species.

AbstractBackgroundImperfect detection of hard‐to‐sample organisms has motivated the development of novel monitoring techniques. Environmental DNA (eDNA) can provide a sensitive, relatively low‐cost sampling method in aquatic systems, but biotic and abiotic factors can affect its reliability.AimsWe used a reintroduced population of radio‐tracked alligator snapping turtles (Macrochelys temminckii) to test the efficacy and ecology of eDNA in a lotic system.Materials & MethodsWe collected samples at turtle locations as well as random up‐ and downstream sites. Using a novel eDNA assay, we modeled occupancy and detection of eDNA using turtle biomass and remotely sensed UV exposure and also tested the relationship between these parameters and eDNA concentration.ResultsWe found eDNA occupancy was best explained by upstream biomass and detection probability decreased with greater upstream UV exposure. The concentration of eDNA in a sample was not significantly affected by biomass measures, but decreased with higher upstream UV exposure, and the effect was significant.DiscussionOur results show that UV exposure can affect aquatic eDNA sampling in situ with free‐ranging animals. The use of radiotelemetry allowed for higher control when modeling eDNA persistence and transport in a natural setting relative to laboratory, enclosure, or mesocosm studies.ConclusionWe propose using wildlife tracking techniques to provide added realism to studies of eDNA dynamics.

The acute phase response is a highly conserved reaction to infection, inflammation, trauma, stress, and neoplasia. Acute phase assays are useful for wildlife health assessment, however, they are infrequently utilized in reptiles. This study evaluated erythrocyte sedimentation rate (ESR) in eastern (Terrapene carolina carolina) and ornate box turtles (Terrapene ornata ornata) and hemoglobin-binding protein (HBP) in T. ornata. Erythrocyte sedimentation rate in 90 T. carolina and 105 T. ornata was negatively associated with packed cell volume and was greater in unhealthy turtles (p < 0.05). Female T. ornata had higher ESR values than males (p < 0.05). Measurement of ESR with a microhematocrit tube proportionally overestimated values from a commercial kit (Winpette), though both methods may retain utility with separate reference intervals. Hemoglobin-binding protein concentration in 184 T. ornata was significantly increased in adults and unhealthy turtles (p < 0.05). Erythrocyte sedimentation rate values were similar between seasons and populations, and HBP values were consistent between years, indicating that these analytes may have more stable baseline values than traditional health metrics in reptiles. This study demonstrates that ESR and HBP are promising diagnostics for health assessment in wild box turtles. Incorporating these tests into wild herptile health assessment protocols may support conservation efforts and improve ecosystem health monitoring.

We tracked yearly variation in breeding phenology in relation to weather parameters in a common European toad population from the southeastern part of its range. Phonological data were collected from 2001 to 2003 and from 2011 to 2017 and compared to open-access daily weather data from a nearby weather station. Data analysis revealed no significant effect of weather on initiation of breeding and a negative relationship between mean daily humidity and mean cloud cover on the duration of breeding season (P = 0.03). Further analysis showed a decreasing trend in breeding season humidity in the past 70 years. Our results predict a tendency toward longer toad breeding seasons in years with drier winter/spring. A projected decrease in humidity in this region could prolong toad breeding season, potentially exposing adults to higher predation. Therefore, the scenario of further decline in our study population should be considered and conservation measures planned accordingly.

Reptiles are declining worldwide yet our understanding of their immune function lags far behind other taxa. The innate immune system is the primary mode of defense in reptiles, and the serum complement cascade is its major component. We assessed serum complement activity of plasma in two closely related aquatic turtle species, the common snapping turtle (CST; Chelydra serpentina) and alligator snapping turtle (AST; Macrochelys temminckii). We used a sheep red blood cell (SRBC) hemolysis assay to assess serum complement activity. Although the antibacterial activities of the plasma of these turtle species are similar, the hemolytic activity was much stronger in CST than AST. Treatment with inhibitors of the serum complement cascade indicated differences in the mechanisms of complement activation between the turtle species. We subjected plasma from both turtle species to mannan affinity chromatography and analyzed the eluate with SDS-PAGE, which revealed that plasma from the CSTs contained only small amounts of one C-type lectin protein while the AST plasma contained high concentrations of two C-type lectins (31.0 and 35.9 kDa). Edman degradation analyses confirmed that the two AST proteins contained identical N-terminal sequences. Thus, the CST appears to rely more heavily on the alternative mechanism of serum complement activation, while the AST appears to rely more on the lectin-mediated pathway, which is a pattern recognition response to prokaryotes not activated by the SRBCs. These results are unique in that the use of serum complement pathways are generally assumed to be conserved within clades.

Population-level data are urgently needed for amphibians in light of the ongoing amphibian extinction crisis. Studies focused on population dynamics are not only important for rare species but also for common species which shape ecosystems to a greater degree than those that are rare. Some of the greatest global amphibian species diversity is found in Madagascar, yet there are few studies on the ecology of frog species on the island. We carried out a mark-recapture study on the widespread frog Mantidactylus betsileanus (Mantellidae: Mantellinae: Mantidactylus) at two adjacent rainforest sites in east-central Madagascar to assess its population size and structure. To do so, we validated and implemented an individual identification protocol using photographs of the ventral patterns of frogs and identified individuals with photographic-matching software. Using this rapid, non-invasive survey method, we were able to estimate a density of 26 and 28 frogs per 100 m(2) at each of the two sites sampled. Our results show the rainforests near the village of Andasibe, Madagascar support remarkably high amphibian abundance, helping illustrate the significant ecological role of frogs in this ecosystem. Further, individual frog markings allowed us to develop more precise estimates than traditional survey methods. This study provides a blueprint to augment existing population studies or develop new monitoring programs in Madagascar and beyond.

Innate immunity provides a fast-acting and nonspecific defense against microbial infection, and appears to have particular importance in the immune response of ectothermic vertebrates. Chelonians are a globally distributed and diverse group, yet little is known about their basic immune function. The chelonian family Chelydridae is made up of two genera (Chelydra and Macrochelys), represented in our study by the widespread common snapping turtle ( Chelydra serpentina; CST) and the southeast USA endemic alligator snapping turtle ( Macrochelys temminckii; AST). Our goal was to quantify the innate immune response of the family Chelydridae, using the antibacterial activity of plasma as a measure of immune function. Our results show that the plasma of both species has strong antibacterial properties, but CST plasma kills a higher percentage of bacteria than AST plasma. In addition, while both species showed the highest antibacterial activity at 25 to 30°C, CST plasma retained its antibacterial properties at lower and higher temperatures than AST plasma. Our results indicate that, like many ectotherms, Chelydridae have a relatively strong innate immune response. The stronger, more robust immune response of CSTs compared with ASTs is likely correlated to the differences in geographic ranges but may also have implications for each species' tolerance to anthropogenic habitat degradation and global climate change.

Many reptiles require ultraviolet-B radiation between 290 and 315 nm (UV-B) to synthesize vitamin D3 and process dietary calcium. In captivity, exposure to too little or too much UV-B can result in health problems such as metabolic bone disease. While it is recognized that UV-B is necessary to successfully maintain many reptiles in captivity, the actual levels of UV-B that species are exposed to in nature is poorly known. We measured the UV-B exposure of two species of chameleon (Calumma brevicorne and C. nasutum) in the field in Madagascar over a period of four months. We found that both species were exposed to less UV radiation than that which was available in full sun. Only on rare occasions were chameleons observed in areas with a UV Index (UVI) greater than 3.0, and the median UVI for both species was only 0.3. There was no daily temporal pattern in UV exposure for C. nasutum, but C. brevicorne was found in areas with lower UV levels in the late afternoon when compared to late morning. Additionally, C. nasutum males showed higher UV exposure than females in late morning. Our results suggest that both C. brevicorne and C. nasutum can be classified as Ferguson Zone 1 species, and should be provided with a UV-B gradient in captivity that offers access to UV-B radiation as well as adequate shaded refuge.