Meeting Abstract

P2.77  Sunday, Jan. 5 15:30  The influence of nest-site choice and nest temperature on hatchling painted turtle survival during hibernation MITCHELL, TS*; WARNER, DA; JANZEN, FJ; Iowa State University; University of Alabama at Birmingham; Iowa State University timmitch@iastate.edu

Many animals are exposed to wide temperature ranges and have behaviorally or physiologically adapted to survive thermal extremes. Yet thermal extremes can still be a major source of mortality and strong selective pressure in many natural populations. Hatchlings of many species of temperate turtles delay emergence from their nest until spring, thus spending their first winter in the maternally-selected, terrestrial nest where they are exposed to subzero temperatures. The mother turtle may be able to influence overwinter environmental conditions in the nest by selecting nest sites with particular attributes, thus ensuring her offspring avoid lethal conditions. We conducted an 8-year study of the hibernation ecology of painted turtles (Chrysemys picta) in western Illinois. Each year we measured vegetation cover above the nest at oviposition, and subsequently monitored nest temperature and hatchling survival over winter. Our study addresses two questions: 1) Does maternal nest-site choice in summer typically influence environmental conditions within the nest over winter? 2) What is the relationship between overwinter nest temperature and hatchling survival in the wild? Our results suggest nest-site choice at oviposition does not influence nest environmental conditions during winter in most years and is therefore unlikely to be under strong selection during this stage. Minimum nest temperature was a strong predictor of hatchling survival over winter suggesting that hatchlings in natural nests are frequently exposed to lethal temperatures. There is likely strong selection in some years on physiological traits that allow hatchlings to tolerate or avoid freezing.