Occupancy Modeling for an Imperiled Reptile

Occupancy modeling can be used to determine the chance that a species is present or absent at a habitat patch, based on detection probabilities. We report preliminary findings about occupancy modeling for the Copper-bellied Watersnake (Nerodia erythrogaster neglecta). We conducted this study in the area occupied by the federally threatened populations of this snake, which is also endangered in IN, MI, and OH. We also recorded occupancy data (presence or absence) for two other snake species that are both common in the copperbelly’s range, the Northern Watersnake (Nerodia sipedon sipedon) and the Northern Ribbon Snake (Thamnophis sauritus septentrionalis) in order to compare detection probabilities and occupancy estimates for the species. The data indicate that copperbellies are observed less frequently than other species because they are more rare, not because they are detected less frequently when actually present than other snakes.http://opus.ipfw.edu/stu_symp2015/1028/thumbnail.jp