Dietary shifts of sympatric buteos during a prey decline

摘要: Diets of nesting Red-tailed Hawks (Buteo jamaicensis) and Ferruginous regalis) were sampled before after a decline in the hawks' principal prey species. pairs that shared their foraging ranges with interspecifics contrasted those whose home did not overlap interspecifics. Current theory predicts diets should diverge during shortages be especially reduced Species composition two diverged shortage, but divergence was most pronounced hawks share In contrast to predictions, species converged on similar-sized shortage. Available data differences habitat availability at sample sites explain deviations from predicted response. Although our findings diet shifts differ other studies, implications are consistent observations others who have studied assemblages mammal-feeding raptors. We conclude we directly affected by interspecific competition do necessarily imply is occurring.