PACKARD, M.J.*; PACKARD, G.C.: Why Hatchling Painted Turtles Overwinter in Their Nest
We placed hatchling painted turtles (Chrysemys picta) individually into pint-volume canning jars containing damp soil or artificial pond water and then exposed the animals to 4oC in a simulated hibernation lasting 70 days. Our goal was to gain new insight into why baby painted turtles remain inside the natal nest for the first winter of their life and thereby expose themselves to potentially lethal conditions of ice and cold. The usual explanation for this behavior holds that hatchlings remaining in their nest over the winter minimize their exposure to predators at a time of year when the potential for growth is low. However, few of the turtles in our experiment survived 70 days of immersion in pond water whereas all the animals survived for 70 days in soil. Hatchlings in pond water may have succumbed to osmo-ionic imbalance, insufficiency of gas exchange, or some unidentified factor. Nevertheless, the overwintering behavior of neonatal painted turtles may be related to limitations of their physiology and not to some reduction in the risk of predation. Supported by NSF (IBN-9612562).
