Influence of temporary emigration on wood turtle (Glyptemys insculpta) detectability, with implications for abundance estimation.

Reliable population estimates are important for making informed management decisions about wildlife species. Standardized survey protocols have been developed for monitoring population trends of the wood turtle (Glyptemys insculpta), a semi-aquatic freshwater turtle species of conservation concern throughout its distribution in east-central North America. The protocols use repeated active search surveys of defined areas, allowing for estimation of survey-specific detection probability (p) and site-specific abundance. These protocols assume population closure within the survey area during the survey period, which is unlikely to be met as wood turtles are a highly mobile species. Additionally, current protocols use a single-pass design that does not allow for separation of availability (pa) and detectability (pd). If there are systematic influences on pa or pd that are not accounted for in the survey design or data analysis, then resulting abundance estimates could be biased. The objectives of this study were to determine if pa is a random process and if pa and pd are influenced by demographic characteristics. We modified the wood turtle survey protocol used in the upper Midwest to include a double-pass design, allowing us to estimate pa and pd using a robust design capture-recapture model. The modified protocol was implemented at 14 wood turtle monitoring sites in Minnesota and Wisconsin between 2017 and 2022. Our results indicated that pa was non-random and that pd increased with turtle carapace length. Our study suggests that model assumptions for current wood turtle population models may be violated, likely resulting in an overestimation of abundance. We discuss possible protocol and modeling modifications that could result in more accurate wood turtle abundance estimates.

Climatic and geographic predictors of life history variation in Eastern Massasauga (Sistrurus catenatus): A range-wide synthesis.

Elucidating how life history traits vary geographically is important to understanding variation in population dynamics. Because many aspects of ectotherm life history are climate-dependent, geographic variation in climate is expected to have a large impact on population dynamics through effects on annual survival, body size, growth rate, age at first reproduction, size-fecundity relationship, and reproductive frequency. The Eastern Massasauga (Sistrurus catenatus) is a small, imperiled North American rattlesnake with a distribution centered on the Great Lakes region, where lake effects strongly influence local conditions. To address Eastern Massasauga life history data gaps, we compiled data from 47 study sites representing 38 counties across the range. We used multimodel inference and general linear models with geographic coordinates and annual climate normals as explanatory variables to clarify patterns of variation in life history traits. We found strong evidence for geographic variation in six of nine life history variables. Adult female snout-vent length and neonate mass increased with increasing mean annual precipitation. Litter size decreased with increasing mean temperature, and the size-fecundity relationship and growth prior to first hibernation both increased with increasing latitude. The proportion of gravid females also increased with increasing latitude, but this relationship may be the result of geographically varying detection bias. Our results provide insights into ectotherm life history variation and fill critical data gaps, which will inform Eastern Massasauga conservation efforts by improving biological realism for models of population viability and climate change.

Detection of Ophidiomyces, the Causative Agent of Snake Fungal Disease, in the Eastern Massasauga ( Sistrurus catenatus ) in Michigan, USA, 2014.

Snake fungal disease (SFD), caused by Ophidiomyces ophiodiicola, threatens free-ranging snake populations across the US. We assayed 112 swabs from 102 individual eastern massasaugas ( Sistrurus catenatus ) at three locations in Michigan in 2014 for Ophidiomyces using quantitative PCR (qPCR). We observed a 12.7% qPCR prevalence of skin lesions. Individuals at each site had lesions, and occurrence of skin lesions was not significantly different between sites. We detected Ophidiomyces DNA at each of the three sites in five individuals (4.9%). We found no difference in detection probabilities between sites; however, snakes with dermatitis had higher Ophidiomyces DNA detection probabilities (P=0.15±0.08 SE) than snakes without dermatitis (P=0.02±0.01 SE, P=0.026). The emergence of SFD mortalities has potentially serious consequences for the viability of the eastern massasauga in Michigan. Future work should track temporal patterns in vital rates and health parameters, link health data to body condition indices for individual snakes, and conduct a "hotspot" analysis to examine health on a landscape scale.

PLASMA ELECTROPHORETIC PROFILES IN THE EASTERN MASSASAUGA (SISTRURUS CATENATUS) AND INFLUENCES OF AGE, SEX, YEAR, LOCATION, AND SNAKE FUNGAL DISEASE.

The purpose of this study was to establish reference intervals of the protein electrophoretic fractions and the acute-phase proteins hemoglobin binding protein (as determined by the haptoglobin assay) and C-reactive protein (CRP) and assess any possible correlations between varying age class, sex, location (Illinois or Michigan), year, or presence of snake fungal disease (SFD). Banked plasma samples were assayed from 130 eastern massasaugas from 2009 to 2014 in Illinois and Michigan. Snakes from Michigan had higher total protein (mean: 5.50 g/dl), albumin/globulin ratio (0.42), albumin (1.59 g/dl), and gamma globulins (0.55 g/dl) than from snakes in Illinois (4.72 g/dl, 0.29, 1.03 g/dl, 0.38 g/dl, respectively). Snakes in Illinois (22.19 g/ml) had higher CRP than snakes in Michigan (10.89 mg/ml). Adults had higher gamma globulins (0.47 g/dl) than juveniles (0.28 g/dl). Males had higher alpha-2 globulins (0.98 g/dl) and CRP (21.4 mg/ml) than females (0.85, 11.6, respectively). There were no significant differences in absolute plasma proteins in SFD-positive snakes, but the percentage of gamma globulins was significantly higher in positive snakes. Future research in this area can now build on this data to determine changes in population health over time or due to specific environmental or disease threats.