Ferruginous Hawk

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(New page: Image:FerruginousHawk.jpg '''Common Name:''' Ferruginous Hawk '''Scientific Name:''' Buteo regalis '''Size:''' 22-27.2 inches (56-69 cm); '''Wingspan:''' 52.4-56 inches (133-142 cm)...)
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Revision as of 18:38, 11 June 2015


Common Name: Ferruginous Hawk Scientific Name: Buteo regalis

Size: 22-27.2 inches (56-69 cm); Wingspan: 52.4-56 inches (133-142 cm)

Habitat: North America; breeding range is from western North America from southern Canada between the Great Plains and Rocky Mountains. The year round range occurs in the areas of eastern Utah, Colorado, Arizona and New Mexico. The wintering range includes most of California, central and southwestern Colorado, southern Nevada, Arizona and New Mexico, southwestern Nebraska, western Kansas and Oklahoma and a good portion of Texas and down into Mexico.

Ferruginous Hawks are medium distance migrants that travel individually or in small groups. Northern populations tend to migrate more than southern populations, and migrants do not tend to follow leading or diversion lines. Instead, they demonstrate complex migration patterns such as loop migration. Fall migration begins in August and September and their migration from Alberta Canada takes them east of the Continental Divide and south through the Great Plains including Montana, North Dakota, South Dakota and Nebraska following grassland habitat on their way to their wintering grounds in New Mexico .

An open-country species inhabiting semi-arid grasslands with scattered trees, rocky mounds or outcrops, and shallow canyons that overlook open valleys. They may occur along streams or in agricultural areas in migration.

Status: Least Concern to Threatened. Global population: Unknown amount of adult individuals with an increasing population trend. This species has undergone a large and statistically significant increase over the last 40 years in certain areas of North America (155% increase over 40 years, equating to a 26.3% increase per decade.) These population increases appear to be mostly in California. In almost every other state it is found, the species has declined significantly, causing it to be listed as a State Threatened Species. It also carries a federal “Species of Concern” label. Threats include cultivation, over-grazing and fire degrading habitat throughout its range, and the controlling of small mammal populations (prairie-dog towns and gopher populations) limiting food resources.

Diet: Primarily rodents including Richardson's ground squirrels, white-tailed jackrabbits, black-tailed jackrabbits, ground squirrels, pocket gophers, prairie dogs, and kangaroo rats. Other prey includes snakes, lizards, meadowlarks, grasshoppers, and crickets.

The birds hunt in the early morning or late afternoon. There are four distinct modes of attack; short distance strikes on prey from the ground, aerial hunting from low altitudes, aerial strikes from high altitudes (300 feet), and flying after prey from a perch. Hunting from the ground appears to be the more successful of the four methods. Since these birds inhabit open country, they can stand by a burrow and wait for prey to appear.

Like many raptors, prey is swallowed whole or torn into chunks. The Ferruginous hawk then regurgitates a pellet of fur, feathers, bone, and other non-digestible material.

Nesting: Sexes are alike, females average just a bit larger than males. Two color morphs occur, with intermediates. Light morph: Rust colored back and shoulders; head paler, grayish and streaked, and white tail has pale rust wash on end. Undersides are white with limited streaking and rusty spots; leg feathers rust colored on adults, white on juveniles. Large, white crescent-shaped patches occur on the upper wing surface on the primaries. Beneath the wing, large dark comma-shaped patches occur at the wrists. Dark morph: Entire head and body and wing surfaces are dark brown to cinnamon-colored. The yellow gape (mouth) stripe is visible. Upper surface of wing at the base of the primaries shows the white "window", similar to light morphs.

Juveniles are similar to adult, but have lightly banded tail. The light form lacks rufous legs and back.

They select rocky outcrops, hillsides, rock pinnacles, or trees for nest sites. Nests can be built right on the ground and are built of large twigs or roots. The male collects most of the nesting materials, often tugging at roots or attached stems. The female arranges the material and molds the nest cup of grasses, twigs, old bones, and cow or horse dung. Females lay 3 to 4 white eggs, that are blotched with brown, between the months of February and July. Both adults incubate the eggs which take about 28-32 days to hatch. Eggs are laid at two-day intervals; sometimes there is may be a two-week age difference between the oldest and youngest fledgling.

Young fledge from 38 to 50 days old. The smaller males may leave the nest 10 days earlier than their female siblings. The adults will continue to feed the fledged young, as well as the nestlings. The young remain with their parents for several weeks after fledgling (10-40 days) before dispersing on their own.

Cool Facts: The Ferruginous Hawk is the largest American hawk. Before the elimination of bison in the West, nests of the Ferruginous Hawk were often partially constructed of bison bones and wool.

Some observers have found a difference in the number of eggs laid in a ground nest versus a tree nest, with the tree nest having higher average numbers of eggs per clutch. The number of eggs laid, as well as the number of active nests in an area, may be tied to the abundance of prey. Low prey populations may mean lower reproductive success.

Found in Songbird ReMix Birds of Prey Volume 5: Falcons, Hawks & Eagles

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