Ferruginous Hawks are birds of the West and the northern Great Plains, residing in open country. They favor vast expanses of Sagebrush prairie and grasslands in summer, but many move to agricultural or tilled areas in winter. They nest in large trees, on low buttes, power poles, and even sometimes on the ground in remote areas. In summer, they feed mainly on prairie dogs, ground squirrels, and snakes. When perched on power poles, fence posts, and on the ground (especially hilltops) scanning for prey, they appear as a 'hulking' figure. They are unmistakably large and bulky; being on average the largest of the North American buteos. However, the size difference between male and female (which are larger) can be great, with some females over twice the weight of their mate.
Ferruginous Hawks are less common than Red-tailed and Swainson’s Hawks, but highly visible in winter and summer, especially where ground squirrel, prairie dog, or mouse populations are high. They are versatile hunters, adept at stooping from high in the sky, surprising prey in low level direct flight, and also hover and kite in the wind equally as well (if not better) as Red-tailed, Rough-legged, and Swainson's Hawks. In some wintering areas, Ferruginous Hawks roost in groups of up to 100 birds, mixing in with Rough-legged and Red-tailed Hawks. Their call is a quavering, descending, nasal "kreeeeer."
Perched, show broad chest and shoulders, and long wings and tail with the wing tips nearly reaching tail tip.
In a soar, show long, fairly broad wings (slimmer than Red-tailed Hawk) that taper to a point, appearing particularly angular.
When gliding, wing tips extend well past the trailing edge of the wings forming 'M' shape similar to Swainson's Hawks but slightly less pronounced.
In most postures, appear 'chesty' and long-tailed.
Buoyant, teeter from side-to-side similar to Harrier, but less wobbly.
Soar in wide lazy circles.
Wings held in a shallow to pronounced dihedral when soaring. When gliding, wings held in modified dihedral.
Labored, stiff wing beats that are slightly quicker and deeper on the upstroke, and less snappy than Red-tailed Hawk.
Occur in light (common) and dark morph (rare), and two age classes: adult and juvenile. Eyes are yellowish in juvenile, brown in adult, but take several years to fully change. All morphs have whitish flight feathers, lacking distinct barring, with limited black on tips of outer primaries. Yellow gape is prominent compared with other buteos.
Light-morph adult is striking white below with rufous leggings that form a "V" on the belly in flight, rufous marked underwing coverts, some lightly marked and others nearly fully rufous. Some have rufous barring on the belly. From above, brownish-gray with brilliant rusty-orange upperwing coverts that contrast grayish flight feathers and white primary "panels." Tail is whitish, reddish, or grayish mottled.
Light-morph juvenile is bright white underneath, but lightly spotted brown on the legs and belly Some show fairly mottled underwings. Tail has white base and dark distal. Uniformly brown above with bold white primary "panels" and a white base to the tail.
Dark-morph adult is rufous-brown underneath with pale flight feathers. Brown to slate-brown above with faint rufous upperwing coverts. The topside of the tail is typically grayish, or grayish with whitish mottling.
Dark-morph juvenile similar to dark adults but trailing edge of the wings is less bold, underside less colorful, and tail is plain brown, sometimes with white base.
Short or medium-distance migrant. Infrequently seen throughout the West during migration with no true peak time period.
Flights occur later in fall (October through November) at the southern range of their migration, and earlier at the northern part of their range (September through October); the opposite is true for spring migration.
Adults arrive back in spring (mainly March through April) before juveniles, some adults don't migrate at all.
Dinosaur Ridge, CO, and the Wasatch Range, UT are the most reliable sites to witness Ferruginous Hawk migration. The Goshute Mts., NV and Marin Headlands, CA are fairly reliable sites as well.
(Map from Cornell Lab of Ornithology's All About Birds. For dynamic distribution maps, visit the eBird website.)