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, M. A. Welsh

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

Two related aspects of hatchling emergence were studied in a population of pig-nosed turtles (Carettochelys insculpta) 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 synchronized with initial river rises associated with the onset of wet-season rains, and is consistent with published criteria for embryonic aestivation. On a diel scale, we generated predictions of two potentially competing models of nocturnal emergence in hatchling turtles based on the knowledge that air temperatures decrease with season during the emergence period. A test of these predictions for C. insculpta produced ambiguous results. However, further analysis indicated that C. insculpta, and probably other nocturnally emerging turtle species, respond to a decline in diel temperature rather than to an absolute temperature. The former would ensure nocturnal emergence, while the latter is experienced during the day as well as at night. Nocturnal emergence may be associated with nesting in open microhabitats.

Original languageEnglish
Pages (from-to)1062-1072
Number of pages11
JournalCanadian Journal of Zoology
Volume79
Issue number6
DOIs
Publication statusPublished - Jun 2001
Externally publishedYes

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