Avian Nutritional Ecology

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Nutritional requirements vary through the seasons in free- living animals, and must be fulfilled from food supplies that also vary in both quantity and quality. The study of the ways (physiological, morphological, behavioral) in which such animals match supply and demand or cope with shortage is often called "nutritional ecology." This project concerns four aspects of the nutritional ecology of an archetypical omnivorous bird, the White-crowned Sparrow: (1) By what metabolic and behavioral responses do small birds minimize or tolerate nutritional privation? What are the differences in the limits of acute and chronic privation? (2) Do the caloric and amino-acid costs of molt (a process representing a nutritional bottleneck in the annual cycle) vary with photoperiod (and hence with latitude)? (3) What accounts for the very low caloric efficiency of molt (5-10%) compared with that of other forms of production (40- 80%)? (4) Do molting birds renovate their skeleton together with their plumage? If so, does this help explain the apparently large cost and low efficiency of molt? The answers to these questions will provide a basis for understanding better the labile nutritional requirements of animals in the wild.