COS 140-1 - Diel and seasonal aquatic–terrestrial habitat selection patterns for a northern population of wood turtles

Abstract: Many wildlife species exhibit complex spatiotemporal activity and habitat use patterns to meet their biological needs. Characterizing these patterns and the influence of environmental conditions on movement dynamics can improve our understanding of habitat requirements and inform predictions of how species will respond to environmental changes. Wood turtles (Glyptemys insculpta) are unique semiaquatic freshwater turtles that require streams for hibernation and thermoregulation but heavily use terrestrial environments during the active period. Previous wood turtle space use studies have mainly focused on delineating location and size of activity areas and assessing terrestrial habitat selection during daylight hours. Recent advances in GPS technology allow for tracking spatial dynamics over long periods with fine temporal resolution. The objectives of our study were to characterize diel aquatic–terrestrial habitat selection patterns of adult male and female wood turtles across the active period, and to quantify the influence of air temperature on selection of aquatic, open canopy terrestrial, and closed canopy terrestrial habitat classes. Between 2015 and 2016, we tracked locations of 23 wood turtles in northeastern Minnesota at 10-minute intervals from May to September using GPS loggers coupled with temperature sensors placed on the turtles and in our focal habitat classes, and used these data to assign turtles to a habitat class at each time step. We used binomial generalized linear mixed models and a model selection approach to assess the influence of six predictors of turtle presence on land, and found that day of year, hour of day, and sex were influential predictors. Both sexes showed a strong pattern of using terrestrial environments during the day and aquatic environments at night, with greater nighttime terrestrial activity by females and in mid-summer. Additional analyses will be performed to quantify the influence of temperature on habitat class selection. Our finding that wood turtles routinely return to streams at night in the warmest months of the year was unexpected and furthers our understanding of how this species uses the environment. We anticipate that temperature will have a strong influence on habitat selection and could explain differences in diel activity patterns across the distribution of the species.