Nesting Populations of Red-Tailed Hawks and Great Horned Owls in Central Ohio
Abstract
Nesting populations of Red-tailed Hawks (Buteo jamaicensis) and Great Horned Owls (Bubo virginianus) were studied from 1974 through 1976 on a 510-km2 (197-sq.-mi.) area located in Delaware County, Ohio.
In 1976, 59 nesting pairs of Great Horned Owls, 6 non-nesting pairs, and 9 unpaired individuals were located, while 78 nesting pairs of Red-tailed Hawks, 7 non-nesting pairs, and 7 unpaired individuals were located. Density of Great Horned Owls was one nesting pair per 8.2 km2 (3.16 sq. mi.) of usable habitat, and density of Red-tailed Hawks was one nesting pair per 6.2 km2 (2.39 sq. mi.). The rate of nonbreeding for Great Horned Owls and Red-tailed Hawks was 15 percent and 12 percent, respectively. Productivity of Great Horned Owls averaged 2.0 eggs per observed clutch, 1.9 nestlings per hatched clutch, 1.7 fledglings per successful nest, and 1.2 young fledged per nesting attempt. Red-tailed Hawk productivity averaged 2.0 eggs per observed clutch, 2.12 nestlings per hatched clutch, 1.96 fledglings per successful nest, and 1.29 young fledged per nesting attempt. Nest failure rate for Great Horned Owls was 25 percent. Red-tailed Hawk nest failure rate was 34 percent, and nestling mortality was 19.7 percent. Causes of Red-tailed Hawk nest failures were largely undetermined although predation by Great Horned Owls was often suspected.
