Microgeographic Variation in Bog Turtle Nesting Ecology

Bog Turtles (Glyptemys muhlenbergii) are cryptic habitat specialists, requiring spring-fed bogs, fens, and wet meadows, and are among the most imperiled turtles in North America. Despite the sensitive conservation status of this species, data on nesting ecology remain scant. We used radiotelemetry to collect information on the nesting ecology and nest success of Bog Turtles at two sites in Maryland. We had three main objectives: 1) to determine elements of reproductive biology critical to population viability, 2) to investigate rates of nest and egg success, and 3) to compare these variables between two proximate geographic localities. We documented a total of 41 nests across both sites and study years, all between 8 and 22 June of each year. In some cases, turtles used the same nest sites between years, and nests were in moist soil, moss, sedge tussocks, and mats of vegetation. Nesting turtles were typically observed in the late afternoon and evening, between 1557 and 2222 h. Clutch sizes averaged 3.52 +/- 1.08 eggs across both sites and years. Nesting success was significantly different between sites, and most nests that did produce surviving hatchlings experienced at least partial depredation before hatching. We stress the importance of collecting site-specific nesting data for this species, and suggest that nest protection may be a useful tool for increasing rates of nest success at some sites.