Evidence for Nest-Site Fidelity but Not Natal Homing in Bog Turtles (Glyptemys muhlenbergii)

Abstract

To mitigate habitat loss and increase the reproductive success of threatened Bog Turtles (Glyptemys muhlenbergii), managers often improve or restore open-canopy nesting habitats within or adjacent to occupied habitat. Restoring nesting habitat, however, does not guarantee that Bog Turtles will use these restored habitats; inertial mechanisms such as nest-site fidelity and natal homing may prevent female Bog Turtles from discovering and using restored habitats for many years or even generations. The objective of this study was to improve understanding of the role behavioral inertia may play in female Bog Turtle nest-site selection. From 2008 to 2012, at nine fens in New York and Massachusetts, we compared the average distance between previous and subsequent nests with null distributions assuming no nest-site fidelity. We also assessed whether pairwise genetic relatedness of nesting females was positively associated with geographic distance between nests. We found evidence for strong but incomplete fidelity to nesting-habitat patches within a wetland, likely driven by behavioral inertia. Individuals nesting closer together were not more closely related, and first-degree female relatives did not consistently nest within the same nesting-habitat patch, suggesting that Bog Turtles do not exhibit natal homing. Our results suggest that Bog Turtle populations may be slow to respond to newly restored nesting areas because of behavior inertia. However, testing this hypothesis will require long-term monitoring of habitat-restoration efforts coupled with further investigations of Bog Turtle nest-site selection.