title: Potential sources of intra-population variation in the overwintering strategy of painted turtle (Chrysemys picta) hatchlings.
abstract: Many temperate animals spend half their lives in a non-active, overwintering state, and multiple adaptations have evolved to enable winter survival. One notable vertebrate model is Chrysemys picta, whose hatchlings display dichotomous overwintering strategies: some hatchlings spend their first winter aquatically after nest emergence in the autumn, whereas others overwinter terrestrially within their natal nest with subsequent emergence in the spring. The occurrence of these strategies varies among populations and temporally within populations; however, factors that determine the strategy employed by a nest in nature are unknown. We examined potential factors that influence intra-population variation in the overwintering strategy of C. picta hatchlings over two winters in Algonquin Park, Ontario. We found that environmental factors may be a trigger for the hatchling overwintering strategy: autumn-emerging nests were sloped towards the water and were surrounded by a relatively higher percentage of bare ground compared with spring-emerging nests. Autumn-emerging hatchlings were also relatively smaller. Overwintering strategy was not associated with clutch oviposition sequence, or mammalian or avian predation attempts. Instead, autumn emergence from the nest was associated with the direct mortality threat of predation by sarcophagid fly larvae. Body condition and righting response, measured as proxies of hatchling fitness, did not differ between overwintering strategies. Costs and benefits of overwintering aquatically versus terrestrially in hatchling C. picta are largely unknown, and have the potential to affect population dynamics. Understanding winter survival has great implications for turtle ecology, thus we emphasize areas for future research on dichotomous overwintering strategies in temperate hatchling turtles.
authors.affiliation: Department of Biology, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada.
authors.forename: Julia L
authors.initials: JL
authors.lastname: Riley
authors.affiliation: Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada.
authors.forename: Glenn J
authors.initials: GJ
authors.lastname: Tattersall
authors.affiliation: Department of Biology, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada jlitzgus@laurentian.ca.
authors.forename: Jacqueline D
authors.initials: JD
authors.lastname: Litzgus
mesh_terms: D000818:Animals; D049628:Body Size; D017753:Ecosystem; D005260:Female; D006605:Hibernation / Q000502:physiology*; D009425:Nesting Behavior; D009864:Ontario; D010058:Oviposition; D011235:Predatory Behavior; D058493:Sarcophagidae; D012621:Seasons; D014426:Turtles / Q000502:physiology*; D014867:Water
chemical_list: D014867:Water
keywords: Body condition; Fitness; Freeze tolerance; Maternal effects; Nest environment; Nest predators; Supercooling; Temperature