Dispersal from and fidelity to a hibernaculum in a northern Vermont population of Common Map Turtles, Graptemys geographica

Adult female Common Map Turtles, Graptemys geographica, ranging in carapace length from 160-260 mm were tracked with sonic equipment from November 1997 to November 1998. Seven of the 15 turtles tagged initially in 1997 returned to the same river hibernaculum in 1998. SCUBA observation demonstrated that hibernating females clustered together shell to shell in small and large groups often piled upon one another. They wintered fully exposed (unburied) but frequently positioned themselves against bottom debris (rocks, ledge outcrops, submerged logs). Ice covered the river from December through March. In April, when the ice had thawed, the animals emigrated to their summer home ranges. Range length for 6 females was 1.5-8.0 km along the river course. Total movements outside the hibernaculum ranged from 3.1-15.4 km. Some individuals moved downstream to Lake Champlain (2.7 km) and along the lakeshore as much as 2.2 km from the river's mouth. One individual moved 5.8 km upstream, then headed 9.5 km downstream to the lake before returning to the hibernaculum.