Habitat and temperature selection of Clemmys guttata in a northern population

We used temperature-sensitive radiotransmitters to study habitat use and te mperature selection of spotted turtles (Clemmys guttatu) on an island in Ge orgian Bay, Ontario, Canada. Each of two field seasons was divided into fou r "subseasons": Mating, Nesting, Aestivation, and pre-hibernation, based on seasonal changes in spotted turtle behavior. We observed distinct seasonal shifts in habitat use. In spring (May-June) turtles aggregated in ponds to court and mate. In late June, females nested on open rock outcrops. During July and August, turtles spent about half their time buried in terrestrial forms on rock outcrops and in forests, and were actively swimming and bask ing, and presumably feeding, during the remainder of this subseason. From S eptember to April, turtles hibernated in sphagnum swamps. Using temperature -sensitive radiotransmitters, we determined average body temperatures while turtles were basking (25.3 C) courting and mating (15.1 C) nesting (19.8 C ), foraging and feeding (16.7 C) aestivating (21.8 C) and entering hibernat ion (9.5 C). We also recorded air and water temperatures during these activ ities. Comparisons of body temperatures to air and water temperatures, and observed habitat use, suggested that high summer temperatures and avoidance of desiccation were not the proximate causes of aestivation in this northe rn population.