Species: Buteo regalis

Ferruginous Hawk

Species

Encyclopedia of Puget Sound

A hawk with a rusty back and shoulders, paler head, and white tail washed with pale rust; white patch at the base of the flight feathers on the upper wing surface; dark legs of adult contrast with whitish underparts; uncommon dark phase lacks dark tail bands; averages 58 cm long, 135 cm wingspan (NGS 1983).

Classification

Kingdom

Animalia

Phylum

Craniata

Class

Aves

Order

Falconiformes

Family

Accipitridae

Genus

Buteo

NatureServe

Source:
ELEMENT_GLOBAL.2.103222

Classification

Other Global Common Names

Aguililla Real - buse rouilleuse

Informal Taxonomy

Animals, Vertebrates - Birds - Raptors

Formal Taxonomy

Animalia - Craniata - Aves - Falconiformes - Accipitridae - Buteo

Ecology and Life History

Short General Description

A carnivorous bird (hawk).

Migration

false - true - true - Arrives in northern breeding range (South Dakota) by March-early April, in Utah and Colorado mostly in late February-early March; yearlings arrive later. Adults depart northern end of breeding range by late October; young depart in August. Wintering areas of grassland and desert shrub breeders are mainly separate. (Schmutz and Fyfe 1987). Alberta populations winter mainly in Texas. In southern breeding range, may be short-distance migrant or possibly sedentary (Palmer 1988).

Non-migrant

false

Locally Migrant

true

Food Comments

Mammals are the primary prey during the breeding season, although birds, amphibians, reptiles, and insects also are taken (Weston 1968, Howard 1975, Fitzner et al. 1977, Blair 1978, Smith and Murphy 1978, Gilmer and Stewart 1983, Palmer 1988, De Smet and Conrad 1991, Atkinson 1992). Primary prey in central grasslands are ground squirrels (SPERMOPHILUS SPP.), followed by pocket gophers (THOMOMYS SPP.) and white-tailed jackrabbits (LEPUS TOWNSENDII) (Bechard and Schmutz 1995). Primary prey in western shrubsteppe are jackrabbits (LEPUS SPP.), followed by ground squirrels and pocket gophers (Smith and Murphy 1978, Bechard and Schmutz 1995). White-tailed (CYNOMYS LEUCURUS) and black-tailed prairie dogs(CYNOMYS LUDOVICIANUS)also serve as prey items (Powers and Craig 1976, MacLaren et al. 1988). In Oregon, Janes (1985) found that the highest abundance of major prey species (white-tailed jackrabbits, Townsend's ground squirrels [SPERMOPHILUS TOWNSENDII], and northern pocket gophers [THOMOMYS TALPOIDES]) occurred in native grasslands. Vulnerability of prey also is an important factor in habitat suitability, such that Ferruginous Hawks avoid dense vegetation that reduces their ability to see prey (Howard and Wolfe 1976, Wakeley 1978, Schmutz 1987). Prey vulnerability decreases where taller small-grain crops replace shorter grasses (Houston and Bechard 1984). Intensive agricultural practices, such as annual plowing and biennial fallowing, exclude many prey species (Wakeley 1978, Houston and Bechard 1984). In Alberta, prey abundance increases as the area of cultivation increases up to 30 percent, but abundance is reduced where agriculture is extensive, e.g., more than 30 percent (Schmutz 1989).

Reproduction Comments

Occur on breeding areas from late February through early October (Weston 1968, Olendorff 1973, Maher 1974, Blair 1978, Smith and Murphy 1978, Gilmer and Stewart 1983, Schmutz and Fyfe 1987, Palmer 1988, Bechard and Schmutz 1995). See Palmer (1988) and Hall et al. (1988) for egg dates in different areas. Clutch size usually is two to four. Incubation lasts about 32-33 days, mostly by female; male provides food. Young fledge in 35-50 days (males before females), depend on parents for several weeks more. No evidence that yearlings breed. Renesting within the same year is rare (Woffinden 1975, Palmer 1988) even when clutch is lost. Territory and nest site reoccupancy is common and one of several nests within a territory may be used in alternate years (Davy 1930, Weston 1968, Olendorff 1973, Blair 1978, Smith and Murphy 1978, Palmer 1988, Roth and Marzluff 1989, Schmutz 1991b, Atkinson 1992, Houston 1995). Mate fidelity also is common. (Schmutz 1991b). Clutch size, fledging rate, and/or breeding density tend to vary with prey (especially jackrabbit [LEPUS SPP.] or ground squirrel [SPERMOPHILUS SPP.]) availability.

Ecology Comments

Density and productivity are closely associated with cycles of prey abundance (Woffinden 1975; Powers and Craig 1976; Smith and Murphy 1978, Smith et al. 1981; Gilmer and Stewart 1983; Houston and Bechard 1984; White and Thurow 1985; Palmer 1988; Schmutz 1989, 1991a; Schmutz and Hungle 1989; Bechard and Schmutz 1995). Estimates of home range size vary from 3.14 to 8.09 square kilometers in the Columbia River Basin and Great Basin regions of the western U.S. (Janes 1985). The average home range was 90.3 square kilometers in Washington, and the variability in home range was significantly related to distance from the nest to the nearest irrigated agricultural field (Leary et al. 1998). One male that nested closest to the surrounding agricultural fields had the smallest home range, whereas another male nesting farthest from the agricultural fields had the largest home range. In Utah, mean home range recorded of 5.9 square kilometers (Smith and Murphy 1973). An area of up to 21.7 square kilometers may be required by one pair for hunting in Idaho (Wakeley 1978). Up to 8-10 nests per 100 square kilomters if local conditions are favorable (see Palmer [1988] for density data in several areas). In 11 study areas, mean nearest neighbor distance was 3.4 kilometers (range 0.8-7.2); in six study areas the mean home range size was 7.0 square kilometers (range 3.4-21.7) (Olendorff 1993). Recent studies in Idaho (McAnnis 1990) and Washington (Leary 1996) found average home ranges of 7.6 square kilometers (minimum convex polygon)/19.4 square kilometers (95 percent harmonic mean) and 70 square kilometers (95 percent minimum convex polygon)/31 square kilometers (85 percent adaptive kernel), respectively. First year mortality generally is around 66 percent in the Great Plains region (Schmutz and Fyfe 1987).

Length

Weight

1231

Conservation Status

NatureServe Global Status Rank

Global Status Last Reviewed

1996-11-22

Global Status Last Changed

1996-11-22

Distribution

Conservation Status Map

Global Range

FH - 20,000 to >2,500,000 square km (about 8000 to >1,000,000 square miles) - FGH - BREEDING: eastern Washington, southern Alberta, southern Saskatchewan, extreme southwestern Manitoba (Bechard and Schmutz 1995), south to eastern Oregon, Nevada, northern Arizona, northern New Mexico, Texas panhandle, extreme western Oklahoma, and western Kansas. Recently discovered breeding in California (Small 1994). Historic breeding range in the southwestern U.S. apparently was much greater than at present (Hall et al. 1988). Two subpopulations are recognized (Bechard and Schmutz 1995); one to the east and another to the west of the Rocky Mountains. NON-BREEDING: primarily southwestern and south-central U.S. south to Baja California and central mainland of Mexico; in the U.S., in largest numbers in western Texas, eastern New Mexico, and western Oklahoma (Root 1988). Winters locally in some more northerly breeding areas (Bechard and Schmutz 1995).

Global Range Code

Global Range Description

20,000 to >2,500,000 square km (about 8000 to >1,000,000 square miles)

ELEMENT_GLOBAL.2.103222