Distribution: The ferruginous hawk, Buteo regalis, breeds in western North America, from south-central Canada to northern Utah and New Mexico (Olendorff 1993). It is absent from spotty locations within the breeding range, such as northeastern Idaho, western Montana, northeastern Wyoming, central Utah, and the Black Hills of South Dakota. The species winters primarily in grasslands and shrub steppes in the western and central United States, as well as in Mexico.
Ecology: The primary food is small mammals. West of the Continental Divide, lagomorphs (rabbits and hares) and pocket gophers are main food items. Although in eastern Utah and western Utah, ferruginous hawks eat large numbers of prairie dogs. East of the Continental Divide, ground squirrels and prairie dogs are typically consumed (Olendorff 1993).
Nesting starts generally in March or April depending on latitude. Nest substrates vary throughout range and shows great flexibility from trees and shrubs (49% of 2,119 nests), cliffs (21%), utility structures (12%), and ground outcrops (10%). Locally use haystacks, abandoned buildings, or ground. Bulky sticks (e.g., sagebrush) are used for nest construction and through time nests become very large (e.g., almost 1.5 m in diameter). Density varies regionally and also temporally as prey densities vary. Fall migration extends from August to late September-early October.
Habitat Requirements: During breeding, flat and rolling terrain in grassland or shrub steppe is most often used. Ferruginous hawks avoid high elevations, forests, and narrow canyons, occurring in grasslands, agriculture lands, sagebrush/saltbush/greasewood shrub lands, and at the periphery of pinyon-juniper forests. Because of a strong preference for elevated nest sites, cliffs, buttes, and creek banks are usually present (Olendorff 1993). During winter, ferruginous hawks use open farmlands, grasslands, deserts, and other arid regions where lagomorphs, prairie dogs, or other major prey items are present (Olendorff 1993).