Multiscale habitat selection of an imperiled stream-dwelling turtle

Abstract

Comprehensive knowledge of habitat requirements is vital to the conservation of species. The dynamic environments inhabited by stream-dwelling taxa are particularly complex and challenging to describe. We investigated habitat selection across multiple spatial scales to identify key habitat characteristics of the flattened musk turtle (Sternotherus depressus), which is a federally threatened species that is poorly studied and imperiled by habitat destruction. From 2013 to 2018, we conducted trapping, visual encounter, and habitat surveys while employing radio telemetry and side scan sonar to explore habitat selection at the population, within home range, and microhabitat levels. Study sites comprised relatively small, second- to fourth-order streams in Alabama, USA. Turtles selected bedrock or rock substrates across multiple scales, while snail prey affected selection only at the within-home-range scale. At the within-home-range scale, turtles selected deeper water. Though inconclusive because 95% confidence intervals overlapped 0, relationships trended toward support for larger streams and more bedrock substrate at the population scale. Results demonstrate that spatial hierarchy of habitat use is relevant to management of riverine turtles. By replicating our habitat survey methods in other streams throughout the flattened musk turtle range, data from this study will aid in identifying areas to focus conservation efforts and provide quantifiable goals for restoration projects. Our research identifies the crucial role of rock and bedrock structures, though these habitat features are threatened by anthropogenic sedimentation.