Body temperature and growth of nestling Northwestern Crows, Corvus caurinus

Abstract

Nestling Northwestern Crows (Corvus caurinus) cannot maintain a steady body temperature on their own at hatching. The temperature of 1-day-old nestlings within 1 min after they were removed from the nest, but kept together and exposed to a mean ambient temperature of 10.6 °C, fell to 34.3 °C, but remained at 40–41 °C after 17 days of age. A steady improvement in thermogenesis was also apparent in single nestlings at the end of 21 min of exposure to ambient temperature, rising from 19 °C on day 1 to 40.6 °C on day 22. Adult females provide the heat that the young initially cannot provide for themselves, but at day 15, females essentially stop brooding to participate fully in gathering food. For the young, the cessation of daytime brooding coincides approximately with the eruption of feathers from their sheaths, the attainment of effective endothermy, the start of maximum daily growth rate of the feathers, and the point of inflection of the growth curve.