Environmental DNA surveys help to identify winter hibernacula of a temperate freshwater turtle

Background and aims Overwintering is a critical part of the annual cycle of animals living at high latitudes, and selection of overwintering sites (hibernacula) is important to population persistence. Identifying the overwintering sites of aquatic species is challenging in areas where water bodies are frozen for significant parts of the year. We tested whether environmental DNA (eDNA) approaches could help to locate them. Materials and methods We conducted environmental DNA surveys of underwater overwintering sites of the northern map turtle ( Graptemys geographica ), a species of conservation concern in Canada. We collected water samples under the ice in winter across a mid‐sized temperate lake and used quantitative PCR with a species‐specific probe to quantify concentrations of map turtle eDNA. Results and discussion We found localized eDNA signals consistent with known overwintering sites and one previously suspected site. The latter was further confirmed using underwater remote operated vehicle (ROV) visual surveys. Conclusions Our study confirms that eDNA can offer insights on a critical part of the annual cycle of aquatic species, for which we know very little.