- 22–27.2 in
- 52.4–55.9 in
- 34.5–73.2 oz
- Larger than a Swainson’s Hawk; smaller than a Golden Eagle
- Ferruginous Rough-leg
- Buse rouileuse (French)
- Aquililla patas asperas (Spanish)
- In winter, groups of 5–10 Ferruginous Hawks congregate in prairie dog towns, striking prey when it emerges. They threaten each other by hopping and flapping their wings, creating a feeding frenzy that may attract more Ferruginous Hawks, along with Golden and Bald Eagles.
- When bison still roamed the west, Ferruginous Hawk nests contained bison bones and hair along with sticks and twigs.
- The bulky sticks of their nests are not easily woven together for tree nesting, so they often build on the remains of pre-existing hawk or crow nests. Conservation managers can take advantage of this, providing artificial nests to help boost populations.
- Ferruginous Hawks and Rough-legged Hawks (plus the Golden Eagle) are the only American hawks to have feathered legs all the way down to their toes.
- Ferruginous means rust-colored, and refers to the reddish back and legs of light-morph birds (which are more common than dark morphs).
- Rivaling the massive Ferruginous Hawk in size is the Upland Buzzard of central Asia, which may be a close relative from the days of the Alaska-Siberia land bridge. Ferruginous Hawk fossils are found across the west and date back to the late Pleistocene.
- The oldest Ferruginous Hawk on record was at least 23 years, 8 months old when it was found in Nevada in 2006.
Ferruginous Hawks are open-country birds that breed in grasslands, sagebrush country, saltbush-greasewood shrublands, and edges of pinyon-juniper forests at low to moderate elevations. Their breeding habitat includes features such as cliffs, outcrops, and tree groves for nesting. West of the Rockies, Ferruginous Hawks spend the winter in grasslands or deserts with abundant rabbits, pocket gophers, or prairie dogs. East of the Rockies they live mostly in grasslands, especially those with abundant prairie dogs.
Ferruginous Hawks have a limited diet of small mammals: rabbits, hares, ground squirrels, prairie dogs, and pocket gophers. West of the continental divide their main prey items are jackrabbits and cottontail rabbits; east of the divide they eat mostly ground squirrels and prairie dogs. Their diet occasionally includes amphibians, reptiles, insects, and birds. They hunt at any time of day using four methods: standing on the ground and striking, detecting prey from a nearby perch, searching on the wing, and (in strong wind) hovering or kiting in place. They sometimes walk, hop, and run on the ground after their prey. On communal feeding grounds in winter, they flush competitors away from their prey by hopping with outstretched wings.
- Clutch Size
- 1–8 eggs
- Number of Broods
- 1 broods
- Egg Length
- 2.3–2.5 in
- Egg Width
- 1.8–2 in
- Incubation Period
- 32–33 days
- Nestling Period
- 38–50 days
- Egg Description
- Creamy white with buff or brown blotches.
- Condition at Hatching
- Helpless, with eyes closed, and covered in down.
The pair builds the nest (or refurbishes an old one) together, with the male bringing most of the materials and the female doing most of the construction. Nest materials include sticks, twigs, old sagebrush stems, plastic and metal debris, and sometimes bones. The nest often measures more than 3 feet high and 3 feet across and may be lined with cow dung, sod, and bark that the female strips from trees. The pair usually completes it in less than a week. If interrupted, they may abandon the site and choose a new one.
The male and female jointly choose a nest site in a lone tree, cliff, utility structure, outcrop, boulder, shrub, knoll, or haystack. Nest height varies considerably, from more than 65 feet high all the way down to ground level. Ground nests are almost always on slopes or hill crests. Elevated nests are built on remains of other species’ nests.
Ferruginous Hawks are usually found alone or in pairs, but in winter they may hunt just a few feet apart from each other and roost in groups of 6–12. They roost on cliffs, haystacks, utility structures, trees, or the ground. They seem to be monogamous (although three adults are sometimes seen at nests) and some may keep their pair bond all year round. Courting pairs soar in wide circles and the male “sky dances” by repeatedly diving and ascending. The pair may then grasp beaks and talons and spiral toward the ground. Ferruginous Hawks often nest in habitat shared by Swainson’s Hawks and Red-tailed Hawks. They are somewhat aggressive during breeding season, chasing and attacking intruders with open talons. Songbirds such as Western Kingbirds nest in the same trees and sometimes attack the hawks, which nevertheless ignore the smaller birds’ young.
Ferruginous Hawk numbers were stable or slightly increased between 1966 and 2015, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 80,000, with 85% spending some part of the year in the U.S., 15% breeding in Canada, and 29% wintering in Mexico. The species rates a 10 out of 20 on the Conservation Concern Score. Ferruginous Hawk is not on the 2016 State of North America's Birds' Watch List. Hunting pressure declined in the twentieth century after the Migratory Bird Treaty Act made it illegal to hunt most species of wild birds. Changes to nesting habitat including agriculture, grazing, small mammal control, mining, and fire may contribute to regional population declines. Ranching, if practiced sustainably (particularly with respect to conserving prairie-dog towns), may be an effective means of conserving Ferruginous Hawk habitat. Other proposed management includes maintaining prey populations and mitigating mining, pipeline construction, and urbanization. In formerly occupied areas where trees are no longer available for nesting, artificial nest platforms help boost populations.
- Bechard, M. J., and J. K. Schmutz. 1995. Ferruginous Hawk (Buteo regalis). Ferruginous Hawk (Buteo regalis). In The Birds of North America Online, No. 172 (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York.
- Crossley, R., J. Ligouri, and B. Sullivan. 2013. The Crossley ID Guide: Raptors. Princeton University Press, Princeton, NJ.
- Dunne, P. 2006. Pete Dunne’s Essential Field Guide Companion. Houghton Mifflin, Boston.
- Ligouri, J. 2011. Hawks at a Distance: Identification of Migrant Raptors. Princeton University Press, Princeton, NJ.
- North American Bird Conservation Initiative. 2016. The State of North
America’s Birds 2016. Environment and Climate Change Canada: Ottawa, Ontario.
- Partners in Flight. 2012. Species assessment database.
- Sibley, D.A. 2014. The Sibley guide to birds, second edition. Alfred A. Knopf, New York.
- USGS Patuxent Wildlife Research Center. 2016. Longevity records of North American Birds.
- USGS Patuxent Wildlife Research Center. 2015. North American Breeding Bird Survey 1966–2015 Analysis.
Short- to medium-distance migrant. Some southern-breeding populations may be sedentary. Migrants generally take routes that do not involve crossing the Rockies. Alberta-to-Texas migrants first move southeast and then south, following grasslands.
Find This Bird
Look for Ferruginous Hawks in the open country of the West, where they may be just a speck soaring high in the sky—albeit a brilliantly white speck, as light-morph Ferruginous Hawks are strikingly pale and distinctive. These birds also perch on telephone poles and also on the ground, where they can be hard to spot. In these wide open spaces, learning to tell their shape at long distances is key to finding them: look for their long, relatively narrow and somewhat pointed wings, much different from a Red-tailed Hawk’s silhouette. Also note their tendency to fly with their wings in a dihedral V shape—slightly raised above the horizontal.