Patterns of survival at subzero temperatures by hatchling painted turtles and snapping turtles

Abstract Neonatal painted turtles (Chrysemys picta) do not emerge from their nest immediately upon hatching but instead remain inside the nest cavity until the following spring. Because the nest chamber is only 7–12 cm beneath the surface of the ground, hatchlings in northerly populations may be exposed to subzero temperatures during their first winter of life. We studied the pattern of survival by hatchling painted turtles exposed to subzero temperatures in a controlled laboratory experiment and discovered that 50% of the animals in our samples could withstand exposure to approximately −8.6°C for 18 hr. In contrast, hatchling snapping turtles (Chelydra serpentina) died at −2°C. This extraordinary ability for hatchling painted turtles to withstand exposure to subzero temperatures is a key feature in the unusual life history of the species and distinguishes painted turtles from other species occurring at high latitudes.