The Heat Budget of Incubating Mountain White-Crowned Sparrows (Zonotrichia leucophrys oriantha) in Oregon

Abstract

A general model of animal heat exchange is modified for the special case of an incubating bird and applied to data describing the microclimate and nest/clutch/parent complex of the mountain white-crowned sparrow in southeastern Oregon. Heat exchange is mainly dependent upon meteorological factors and the measured thermal resistances of the nest and the bird's body. It is relatively insensitive to variation in a number of less exactly quantified factors, such as the thermal resistances of the eggs and the brood patch. Resting energy expenditure is estimated for a typical 24-h cycle and found to average 15% lower in an incubating female than in a bird perching outside of the nest but exposed to the same microclimate.