Embryonic aestivation and emergence behaviour in the pig-nosed turtle, Carettochelys insculpta

J. S. Doody, A. Georges, J. E. Young, M. D. Pauza, A. L. Pepper, R. L. Alderman and M. A. Welsh
Canadian Journal of Zoology, 79, 2001, 1062-1072,
Two related aspects of hatchling emergence were studied in a population of pig-nosed turtles (Carettochelysinsculpta) in northern Australia. Using emergence phenology data, nest temperatures, historical weather data, and a developmental model, we tested the hypothesis that delayed hatching occurs in C. insculpta, and that such a delay would allow hatchlings to time their emergence to match the onset of the wet season. Carettochelys insculpta hatchlings emerged, on average, 17 days after dates predicted from a developmental model. Combined with observations of hatchlings remaining in eggs until emergence, these results confirmed delayed hatching in nature. This delay was synchronised with initial river rises associated with the onset of wet-season rains, and is consistent with published criteria for embryonic aestivation.
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