, Volume 89, Issue 4, pp 321-330

Daily energetics of the Black-capped Chickadee,Parus atricapillus, in winter

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Summary

The Black-capped Chickadee,Parus atricapillus, is a year-round resident of deciduous forests near Ithaca, New York. Chickadees are confronted with high nightly energetic demands, due to their small size (10–12 g) and the subfreezing winter temperatures, which must be met by an adequate energy reserve. The fat stores of Chickadees on midwinter evenings provide slightly more energy then expended overnight, as based on metabolic measurements made in the laboratory.

The Chickadee has a much lower metabolic expenditure overnight than would be predicted for a bird of its size. This is accomplished by regulating nocturnal body temperatures 10–12 °C below normal diurnal body temperature (42 °C). When exposed to 0 °C overnight, Chickadees reduce their hourly metabolic expenditure by 23%.

The nocturnal energetics of the insectivorous Black-capped Chickadee and the granivorous Common Redpoll are compared to illustrate two different strategies for winter residence in the north temperate zone.

This study was conducted while I was supported by a Cornell University teaching assistantship and a National Science Foundation Pre-Doctoral Fellowship. Financial assistance for this study was provided by funds from a National Science Foundation Training Grant (GZ 1377), a National Institutes of Health grant to J. W. Hudson (GM 15889), and a Cornell University Research Grant. I am grateful to J. L. Lincer and D. B. Peakall for use of the Soxhlet fat extraction equipment and to J. W. Hudson and F. H. Pough for thoughtful discussion on the substance of the paper. S. J. Chaplin, M. L. Morton, C. P. Ralph and C. J. Ralph made many helpful comments on the manuscript.