Influences of aquatic and terrestrial habitat characteristics on abundance patterns of adult wood turtles

Wood turtles (Glyptemys insculpta) are a species of conservation concern throughout their geographic distribution. Several studies have investigated individual-level habitat selection of wood turtles in the Upper Midwest in the United States, but the effects of habitat characteristics on abundance are poorly understood. This information is needed to improve landscape-level habitat management and conservation initiatives for the species. Our study aimed to identify important aquatic and terrestrial habitat characteristics and quantify their influence on abundance dynamics of adult wood turtles in the Laurentian Mixed Forest Province ecoregion of Wisconsin and Minnesota, USA. We collected standardized population survey data at 57 sites within the ecoregion between 2016 and 2022. We used N-mixture models with a multi-stage model selection procedure to assess the influence of aquatic and terrestrial predictors on abundance, including several 3-dimensional forest structure metrics derived from airborne Light Detection and Ranging (LiDAR) data. Several aquatic and terrestrial habitat characteristics influenced local abundance patterns of adult wood turtles. The most influential aquatic predictors were stream velocity and stream width, and the most influential terrestrial predictors were mean return height and vertical coefficient of variation of height. Abundance was high at sites containing comparatively narrow streams with moderate velocities. The most supported terrestrial predictors were derived from LiDAR and indicate that complex forest structures support larger wood turtle populations. Our results can be used in forest management strategies to improve habitat quality for wood turtles, such as selective tree harvesting to increase structural diversity, and potentially identify robust populations in under-surveyed areas.