Weather-Dependent Foraging Success and Sibling Aggression in Red-Tailed Hawks in Central Washington

Abstract

Most birds have evolved clutch sizes and related breeding behaviors which permit adults to maximize their genetic contribution to future generations. In many cases, this enhancement is equivalent to (or indistinguishable from) rearing the largest brood(s) of healthy young possible in each breeding season. Data on the behavior and breeding biology of many large predatory birds seem inconsistent with such a view. Weather-dependent delivery of prey by red-tailed hawks (B. jamaicensis) to unfledged young and sibling aggression at a nest in central Washington are reported. Food availability probably affects the number of healthy young the parents are capable of rearing.