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    Ferruginous Hawk Life History

    Habitat

    Habitat GrasslandsFerruginous 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.Back to top

    Food

    Food MammalsFerruginous 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.Back to top

    Nesting

    Nest Placement

    Nest TreeThe 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.

    Nest Description

    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.

    Nesting Facts
    Clutch Size:1-8 eggs
    Egg Length:2.3-2.5 in (5.8-6.4 cm)
    Egg Width:1.8-2.0 in (4.6-5 cm)
    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.
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    Behavior

    Behavior Soaring (raptor)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.Back to top

    Conservation

    Conservation Low ConcernFerruginous 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.Back to top

    Credits

    Bechard, Marc J. and Josef K. Schmutz. 1995. Ferruginous Hawk (Buteo regalis), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

    Crossley, Richard, Jerry Liguori and Brian Sullivan. 2013. The Crossley ID Guide: Raptors: Princeton University Press.

    Dunne, Pete. 2006. Pete Dunne's essential field guide companion: Houghton Mifflin Harcourt.

    Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

    Partners in Flight. 2017. Avian Conservation Assessment Database. 2017.

    Sauer, J. R., D. K. Niven, J. E. Hines, Jr. Ziolkowski, D. J., K. L. Pardieck, J. E. Fallon and W. A. Link. The North American breeding bird survey, results and analysis 1966-2015 (Version 2.07.2017). USGS Patuxent Wildlife Research Center 2017.

    Sibley, David Allen. 2014. The Sibley guide to birds, second edition. Alfred A Knopf, New York.

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