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Influence of nearby basking opportunities on Eastern Massasauga hibernacula selection

Sunnucks, Emily

LaGrage, Seth

Dreslik, Michael J.

Illinois Natural History Survey

University of Illinois Urbana-Champaign

Champaign, Illinois USA

Identifying and designating critical habitat is vital to the long-term survival of threatened and endangered species. However, evaluating habitat requirements can be challenging for species whose habitat choices are seasonally or ontogenetically influenced, such as snakes. In particular, data regarding hibernacula selection remains limited for many snake species. Using 21 years of spring emergence data, we studied the influence of environmental characteristics on hibernacula selection in the Eastern Massasauga. Specifically, we tested the significance of nearby basking opportunities by calculating vegetation height, vegetation density, and solar radiation using high-resolution Lidar (Light Detection and Ranging) data. Values for emergence sites were compared to those from randomly generated points within the study extent. We found emergence locations significantly differed from the random points for all variables; however, only vegetation density demonstrated a significant effect. Vegetation density was higher in areas where hibernacula occurred, suggesting available cover may be more important than basking during ingress and egress. Based on our study, we would suggest continuing habitat management to include areas of dense vegetation. However, future research should consider incorporating other sites with more terrain and canopy variation to properly assess the effect of solar radiation and vegetation height on hibernacula selection.