Hypothermic tolerance in an embryonicAmerican kestrel (Falco sparverius)

American Kestrel (Falco sparverius) Science Article 4


Embryos of several bird species tolerate acute hypothermia. However, the extent to which it can be toleratedby wild species living under natural conditions is poorly documented. At a single American kestrel (Falco sparverius)nest 15 days into incubation, we observed a 21-h bout of egg neglect by the parents during which nest (egg)temperature averaged 12.7 deg C. Normal incubation patterns resumed thereafter, and one of three viable eggs hatched32 days after incubation onset, an incubation period 2.5 days longer than the mean in this study. The nestling appearedto develop and fledge normally. Although embryonic tolerance of extended hypothermia is known to occur in someseabirds, its presence in Falconiformes has not heretofore been recorded. Embryonic hypothermic tolerance may beadaptive in species with extended periods of parental absence during incubation

Keith W. Sockman and Hubert Schwabl, Can. J. Zool. 76: 1399-1402 (1998)

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