Nest Temperatures Predict Nest Emergence of Painted Turtle (Chrysemys picta) Offspring

. Environmental conditions during embryonic development affect morphology, behavior, and survival in turtles. Nest temperature also could affect posthatching traits of offspring, such as emergence behaviors. We monitored thermal conditions in painted turtle (Chrysemys picta) nests along the Mississippi River in Illinois to examine their influence on offspring survival and nest emergence. We recorded hourly temperatures within nest cavities during embryonic development in summer 2016 (n = 34) and after hatching through the following January (n = 15–20). Hatching success and posthatching survival appeared to be largely unaffected by thermal conditions recorded in nests. Emergence of neonates from nests was observed from 19 March through 12 May 2017. Onset of offspring emergence occurred later in the spring for nests with greater exposure to subzero temperatures in winter. For nearly all nests with live offspring, siblings did not emerge en masse, but instead departed the nest across multiple days. Nests with higher mean temperatures during incubation exhibited earlier mean emergence dates in spring, yet emergence duration was positively correlated with thermal maxima experienced in nests in fall and winter. Thus, thermal environments in nests at different times of year apparently elicited variation in spring emergence timing of C. picta hatchlings.