Are Red-tailed Hawks and Great Horned Owls diurnal-nocturnal dietary counterparts?
Red-tailed Hawks (Buteo jamaicensis) and Great Horned Owls (Bubo virginianus) have been portrayed as ecological counterparts that take the same kinds of prey by day and night (Bent 1938, Craighead and Craighead 1956, Austing 1964, Austing and Holt 1966, Springer and Kirkley 1978). Both are widespread, common raptors in North America (Johnsgard 1988, 1990), and both occupy a wide range of habitats, often sympatrically. They are similar in size (Red-tailed Hawk mean mass = 1126 g; Great Horned Owl mean mass = 1354 g; Dunning 1984), and both are considered to have generalized diets, i.e., they do not specialize on specific prey types (Errington et al. 1940, Steenhof and Kochert 1985). Coexisting species segregate their feeding niches primarily by differences along…
