Nest Sites and Habitats of Sympatric Hawks (Buteo spp.) in Washington
Nest sites and nest habitats used by Red-tailed (Buteo jamaicensis), Ferruginous (B. regalis), and Swainson's (B. swainsoni) hawks in Washington state were quantitatively described. Discriminant function analysis showed that each species used specific nesting areas with significant variation among species in the distance to water, distance to human disturbance, nest tree diameter, nest height, nest exposure, type of nest structure, and percentages of grass, shrub, and juniper habitats surrounding nests. Red-tailed Hawks nested closest to water, in the tallest and oldest trees, and in areas with large amounts of shrub and grassland habitat. Ferruginous Hawks nested at lower elevations in locations that were farthest from water and at heights of less than 10 m. Swainson's Hawk nests were closest to roads and human structures and nearly half were in areas where the surrounding habitat was dominated by wheat fields.
Bechard, Marc J.; Knight, Richard L.; Smith, Dwight G.; and Fitzner, Richard E.. (1990). "Nest Sites and Habitats of Sympatric Hawks (Buteo spp.) in Washington". Journal of Field Ornithology, 61(2), 159-170.