Buteo regalis

Ferruginous Hawks are usually between 50-66cm (20-26 in.) in length, have an average wingspan of 134-152cm (53-60 in.) and weigh 980-2030g (2.2-4.5 lb.). They are the largest hawks in North America, and are sexually dimorphic. The female hawk may be up to one-and-a half times larger than the male. "Ferruginous" is derived from the Latin Ferrugo, meaning, "rust", which is the predominant color of this hawk. Adults have a rusty color on their back and shoulders, which extends downward onto the legs. The under-part is a whitish color spotted with rufous. A view of the bird in flight will show that the leg feathers form a V shape against the belly of the hawk. When perched, the gray tips of the hawk's long and broad wings often reach the tip of their white, rust, and gray colored tail. Juvenile Ferruginous Hawks lack the rust colored legs and have less color on their backs (Malik 1987; Clark 1987).

Range mass: 980 to 2030 g.

Widespread and relatively common in appropriate habitats, namely relatively intact native grasslands and shrubsteppe. Reports of local declines, continued loss of habitat, sensitivity to disturbance in a prairie species, and relatively low numbers show this species should be carefully watched and regularly re-evaluated.

Prairies and plains of s Canada to n Mexico.

The ferruginous hawk has the most restricted range of any North American
buteo [5]. Its breeding range extends from eastern Washington north to
southern Alberta, southern Saskatchewan and Manitoba; east to the
Dakotas, Nebraska, Kansas, Oklahoma, and Texas; south to New Mexico and
Arizona; and west to California and Oregon [1,5,6,21]. It winters from
the central and southern parts of its breeding range south to Mexico
[6].

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

2 Cascade Mountains
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

AZ CA CO ID KS MT NE NV NM ND OK OR SD TX UT WA WY AB MB SK YT MEXICO

This species occurs in North America, nesting in 17 states in the USA and three provinces in Canada. It winters in the south USA and north Mexico.

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000 to >2,500,000 square km (about 8000 to >1,000,000 square miles)) 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).

The Ferruginous Hawk can be found in North America, as far north as Canada, south through western and central United States to northern Texas. It winters south to northern Mexico (del Hoyo, et. al. 1940).

Biogeographic Regions: nearctic (Native )

Length: 58 cm

Weight: 1231 grams

Dark phase differs from dark-phase rough-legged hawk (BUTEO LAGOPUS) by absence of dark tail bands in the former. Immature resembles Great Plains form of red-tailed hawk (BUTEO JAMAICENSIS) but has larger white wing patches and lacks dark bar on leading edge of underwing (NGS 1983).

Comments: Open country, primarily prairies, plains and badlands; sagebrush, saltbush-greasewood shrubland, periphery of pinyon-juniper and other woodland, desert. In the southern Great Plains, common at black-tailed prairie dog colonies in winter (Schmutz and Fyfe 1987). Nests in tall trees or willows along streams or on steep slopes, in junipers (Utah), on cliff ledges, river-cut banks, hillsides, on power line towers, sometimes on sloped ground on the plains or on mounds in open desert. Generally avoids areas of intensive agriculture or human activity.

Prefer open grasslands and shrubsteppe communities. Uses native and tame grasslands, pastures, hayland, cropland, and shrubsteppe (Stewart 1975, Woffinden 1975, Powers and Craig 1976, Fitzner et al. 1977, Blair 1978, Wakeley 1978, Lardy 1980, Schmidt 1981, Gilmer and Stewart 1983, Green and Morrison 1983, Konrad and Gilmer 1986, MacLaren et al. 1988, Palmer 1988, Roth and Marzluff 1989, Bechard et al. 1990, Black 1992, Niemuth 1992, Bechard and Schmutz 1995, Faanes and Lingle 1995, Houston 1995, Zelenak and Rotella 1997, Leary et al. 1998). Usually occupy rolling or rugged terrain (Blair 1978, Palmer 1988, Black 1992). High elevations, forest interiors, narrow canyons, and cliff areas are avoided (Janes 1985, Palmer 1988, Black 1992), as is parkland habitat in Canada (Schmutz 1991a).

Landscapes with moderate coverage (less than 50 percent) of cropland and hayland are used for nesting and foraging (Blair 1978; Wakeley 1978; Gilmer and Stewart 1983; Konrad and Gilmer 1986; Schmutz 1989, 1991a; Bechard et al. 1990; Faanes and Lingle 1995; Leary et al. 1998). In North Dakota, hayfields and native pastures were the habitats most often used by both fledglings and adults, whereas cultivated fields rarely were used (Konrad and Gilmer 1986). Fledglings in South Dakota hunted in an area where native hay recently had been cut (Blair 1978). When prey densities were low in big sagebrush (Artemisia tridentata)/grassland habitat, agricultural fields served as important foraging areas (Leary et al. 1998). Foraged extensively in alfalfa (Medicago sativa) and irrigated potato fields in Washington and in alfalfa fields in Idaho during the breeding season presumably because of high prey densities (Wakeley 1978, Leary et al. 1998).

Nest site selection depends upon available substrates and surrounding land use. Ground nests typically are located far from human activities and on elevated landforms in large grassland areas (Lokemoen and Duebbert 1976, Blair 1978, Blair and Schitoskey 1982, Gilmer and Stewart 1983, Atkinson 1992, Black 1992). Lone or peripheral trees are preferred over densely wooded areas when trees are selected as the nesting substrate (Weston 1968, Lokemoen and Duebbert 1976, Gilmer and Stewart 1983, Woffinden and Murphy 1983, Palmer 1988, Bechard et al. 1990). Tree-nesting hawks seem to be less sensitive to surrounding land use, but they still avoid areas of intensive agriculture or high human disturbance (Gilmer and Stewart 1983; Schmutz 1984, 1987, 1991a; Bechard et al. 1990).

In eastern Colorado, nested more frequently in grassland areas than in cultivated areas (Olendorff 1973). In North Dakota, preferred to nest in areas dominated by pasture and hayland (Gilmer and Stewart 1983, Gaines 1985). In southwestern Montana, sagebrush (Artemisia) and grasslands predominated within 100 meters of nests (Atkinson 1992). Ground nests in northern Montana were located in grass-dominated, rolling (more than 10 percent slope) rangeland; in general, cropland and areas with dense (more than 30 percent cover), tall (more than 15.24 centimeters) sagebrush were avoided (Black 1992). In western Kansas, most nests were surrounded by more than 50 percent rangeland and 25-50 percent cropland, although one pair incorporated more than 75 percent cropland in its territory (Roth and Marzluff 1989). The majority of nests (86 of 99) were not in direct view of black-tailed prairie dog (Cynomys ludovicianus) towns, although most nest sites were within 8 kilometers of towns (Roth and Marzluff 1989). In Utah, Idaho, Oregon, and California, preferred native grassland and shrubland habitats over cropland, and preferred areas with no perches (Janes 1985). In Washington, some nests occurred in agricultural fields, but most nests were in areas with higher percentages of grassland, shrubland, and western juniper (Juniperus occidentalis) (Bechard et al. 1990). Nest productivity in Idaho was greater in territories with higher amounts of crested wheatgrass (Agropyron cristatum) fields interspersed with desert shrub than in territories with monotypic stands of crested wheatgrass or shrubland, or with greater amounts of Utah juniper (Juniperus osteosperma), alfalfa, and cropland (Howard 1975). In Nevada, open, rolling sagebrush near the pinyon-juniper interface is the preferred landscape for breeding Ferruginous Hawks (GBBO 2010).

In Alberta, however, cultivated areas (11-30 percent of 4,100 hectare plots) had higher nesting densities than grassland areas with 0-11 percent cultivation (Schmutz 1989). In cultivated areas (20 percent) in northcentral Montana, nests closer to cultivated fields and roads were more successful, presumably because of higher prey densities associated with edge habitats (Zelenak and Rotella 1997). The numbers of fledglings produced in unfragmented rangeland versus a mixture of rangeland and cropland were not significantly different in Nebraska (Podany 1996).

The slope, height, and exposure of nests were mostly similar across the species' range. The mean height of ground nests (on buttes or hills) above the surrounding prairie in South Dakota was less than 10 meters, and nests were oriented toward the south and west, providing access to prevailing winds from the south and west (Blair 1978). Lokemoen and Duebbert (1976) found ground nests in South Dakota were all oriented toward the west. Nests in southwestern Montana were significantly oriented toward the south (Atkinson 1992). Nests on rock outcrops in Montana were built on slopes averaging 62.8 percent and were found on the upper 35 percent of the slope (Atkinson 1992). Ground nests in northern Montana were located either on the top of a small rise or on slopes ranging from 10 to 50 percent (Black 1992). Average height of ground nests below the highest surrounding topographic feature was 10 meters, whereas average height of ground nest sites above the valley floor was 10.4 meters, indicating that nests were placed at mid-elevation sites within the immediate topography (Black 1992). Nests in Wyoming were built on a mean slope of 14.26 degrees, and the mean height of nests was 4.55 meters (MacLaren et al. 1988). In southeastern Washington, 86 percent of nests on outcrops and in western junipers were located less than 10 meters from the ground and had southern or western exposures (Bechard et al. 1990). In Oregon shrubsteppe, nests were in relatively short western juniper trees, were less than 10 meters from the ground, and had large support branches (Green and Morrison 1983). In Washington, Idaho, and Utah, the majority of nests also were less than 10 meters from the ground in western juniper and Utah juniper trees (Woffinden 1975, Fitzner et al. 1977, Woffinden and Murphy 1983). Howard (1975) and Howard and Wolfe (1976) also found Utah juniper trees were important nest substrates in southern Idaho and northern Utah. In Utah, nests were built 2-3 meters from the ground, were most commonly located on the sides or summits of hills, and often had southern or eastern exposures (Weston 1968). Woffinden (1975) found that the majority of nests in Utah were on slopes ranging from 15 to 80 degrees with a mean of 42.5 degrees.

More info for the terms: cover, tree

Wooded foothills interspersed with valleys and large desert expanses
provide optimal nesting sites for the ferruginous hawk because of the
combination of human inaccessibility and ease of surveillance of the
surrounding area. Tree nests are often exposed, providing protection
from ground predators and shade for nestlings [11]. Ground nests are
concealed. In South Dakota, ground nests were always located in
prairies with tall herbaceous cover or prairies that were in a lightly
grazed condition [16]. On the plains of Colorado, ferruginous hawks
used fenceposts, telephone poles, and dead trees as perch sites [11].

More info for the terms: interference, scoria, shrub, swamp, tree

The ferruginous hawk inhabits semiarid to arid western plains and
intermountain regions [6]. It occupies open country with scattered
trees, primarily prairies, plains, and badlands [1,6]. The ferruginous
hawk avoids high elevations, forest interiors, steep, narrow canyons, and
high cliffs [12,21].

Nesting habitat - Ferruginous hawk nesting habitat consists of
communities with isolated trees, woodland edges, buttes, cliffs, and/or
grassland with some relief. Ferruginous hawks generally nest within a
short distance of their food supply [11]. Most ferruginous hawk nesting
studies report a preference for tree nests [16,20,27]. However,
ferruginous hawks will use a wide variety of sites, including riverbed
mounds, cutbanks, small hills, small cliffs, powerline structures, and
haystacks [6].

Tree nests are usually in the upper canopy, from 6 to 55 feet (2-17 m)
above the ground [6]. The nest tree is typically isolated or is in an
isolated small cluster of trees in an exposed location. Juniper is the
most commonly used tree for nesting, but pine (Pinus spp.), willow
(Salix spp.), cottonwood (Populus spp.), swamp oak (Quercus spp.), and
sagebrush have been used [16,21]. In northern Utah and southeastern
Idaho, Howard and Wolfe [10] reported that Utah juniper (Juniperus
osteosperma) provided sites for 95 percent of the observed ferruginous
hawk nests. Desert shrub types and Fairway wheatgrass (Agropyron
cristatum)-seeded areas comprised the dominant vegetation around nest
sites [10]. Of the active ferruginous hawk nests in the Centennial
Valley of the Greater Yellowstone Ecosystem, 70 percent were in willows
along streams [5]. Ferruginous hawks will nest in trees and large
shrubs along the edge of forests and wooded areas that are adjacent to
open areas [11].

Ground nests tend to be on slopes, knolls, and crests of ridges, often
on or lodged between boulders [21]. The ferruginous hawk will accept
both modified and completely artificial nest structures. Use of
artificial structures for nesting appears to occur most often when
natural nesting substrates are scarce or unavailable [11].

Of 71 ferruginous hawk nests on the plains of Colorado, 69 percent were
in trees, 11.3 percent on erosional remnants, 5.6 percent on the ground,
5.6 percent on cliffs, 5.6 percent on creekbanks, and 2.9 percent on
artificial structures [20]. Ground nests in southern Idaho were
constructed in areas of rangeland where no suitable nest trees were
available. They were usually located near a small hill [11]. In
Campbell and Converse counties, Wyoming, the majority of ferruginous
hawk nests were built on the ground, usually on a fairly prominent rock,
eroded creekbank, or sandstone or scoria outcrop. Ground nests were
often built in new locations in successive years [22].

Foraging habitat - The ferruginous hawk generally forages in open
habitats with short vegetation containing abundant prey [11,12]. The
best habitat is occupied by high quality prey on over 75 percent of the
home range. This estimate is based on data that indicate that
ferruginous hawks generally hunt over large portions of their home
range. High quality food is not required over 100 percent of the area
because the effective hunting range is usually smaller than the home
range. Food suitability for the ferruginous hawk is optimum when the
vegetation occurs at a mix of heights and densities which optimizes prey
abundance and minimizes hunting interference [11]. The ferruginous hawk
hunts mainly in early morning and late afternoon from low flights and
perches [5].

Winter habitat - The ferruginous hawk inhabits open terrain from
grasslands to deserts during migration and winter. It is the most
common wintering buteo on wide expanses of treeless terrain [21].

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the terms: cactus, shrub

K023 Juniper - pinyon woodland
K024 Juniper steppe woodland
K031 Oak - juniper woodlands
K032 Transition between K031 and K037
K038 Great Basin sagebrush
K040 Saltbush - greasewood
K041 Creosotebush
K042 Creosotebush - bursage
K043 Paloverde - cactus shrub
K044 Creosotebush - tarbush
K053 Grama - galleta steppe
K054 Grama - tobosa prairie
K055 Sagebrush steppe
K056 Wheatgrass - needlegrass shrubsteppe
K057 Galleta - three-awn shrubsteppe
K058 Grama - tobosa shrubsteppe
K059 Trans-Pecos shrub savanna
K064 Grama - needlegrass - wheatgrass
K065 Grama - buffalograss
K066 Wheatgrass - needlegrass
K067 Wheatgrass - bluestem - needlegrass
K068 Wheatgrass - grama - buffalograss
K069 Bluestem - grama prairie
K074 Bluestem prairie
K075 Nebraska Sandhills prairie
K076 Blackland prairie
K077 Bluestem - sacahuista prairie
K079 Palmetto prairie
K086 Juniper - oak savanna
K088 Fayette prairie

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES21 Ponderosa pine
FRES28 Western hardwoods
FRES29 Sagebrush
FRES30 Desert shrub
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands

The ferruginous hawk inhabits grasslands, sagebrush (Artemisia spp.)
scrub, saltbush (Atriplex spp.)-greasewood (Sarcobatus spp.) scrub, and
the periphery of pinyon (Pinus spp.)-juniper (Juniperus spp.) and other
woodlands [11,21]. The ferruginous hawk is an obligate grassland or
desert-shrub nester [26,33]. Ecotones between pinyon-juniper and
sagebrush scrub are commonly used by the ferruginous hawk in the
semiarid western United States [11].

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

220 Rocky Mountain juniper
222 Black cottonwood - willow
235 Cottonwood - willow
238 Western juniper
239 Pinyon - juniper

Habitat and Ecology

Systems

• Terrestrial

The Ferruginous Hawk is most often found in the interior in lowlands, plateaus, valleys, plains, rolling hills of grass land, agricultural land, ranches, and the edges of deserts (Clark 1987).

Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

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).

More info for the term: presence

The ferruginous hawk feeds primarily on rabbits (Lepus spp. and
Sylvilagus spp.), ground squirrels (Spermophilus spp.), and prairie dogs
(Cynomys spp.), but also takes mice, rats, gophers, birds, snakes,
locusts, and crickets [6,11,21]. Analysis of prey items collected from
nests indicate that jackrabbits (Lepus spp.) often constitute the most
important prey item based on biomass [10,23,27,31,33]. A central Utah
study reported that black-tailed jackrabbits (Lepus californicus) made
up more than 95 percent of ferruginous hawk prey biomass [33].

Significant fluctuations in ferruginous hawk densities may be an
indication of the abundance and diversity of prey species. A decline in
ferruginous hawk numbers in Utah was directly correlated with a drop in
the jackrabbit population [11]. Ferruginous hawk fledgling success and
nesting densities in southern Idaho and northern Utah were closely
correlated with the cyclic black-tailed jackrabbit population [28].
However, in years of low prey abundance, ferruginous hawks will often
switch from primary to alternate prey [21,32]. The nesting success of
some populations of ferruginous hawks in Utah, where jackrabbit numbers
declined dramatically, was attributed to the presence of a broad prey
base [32].

Ferruginous Hawks are carnivorous. They commonly hunt by flying low to the ground over open fields at high speeds, soaring high above, hovering, or swooping down from perches. Hawks use their excellent eyesight to spot their prey on the ground and then attack with talons. Ground squirrels, jackrabbits, and mice, as well as birds, reptiles, and amphibians are common prey for this hunter. Depending on the size of the prey, Ferruginous Hawks will swallow it whole, or tear off pieces of the animal with its beak. The portion of the food that can not be digested is then regurgitated into a food pellet (Zeiner 1990; Clark 1987).

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).

Golden eagles (Aquila chrysaetos), prairie falcons (Falco mexicanus),
great horned owls (Bubo virginianus), coyotes (Canis latrans) and red
foxes (Vulpes vulpes) are predators of ferruginous hawk eggs and
nestlings [29].

Buteo regalis preys on:
Lepus californicus
Lepus townsendii
Geomyidae
Sylvilagus
Spermophilus
Eremophila alpestris
Mammalia
Sturnella neglecta
Numenius americanus
Mustelinae
Spermophilus washingtoni

Based on studies in:
USA: California, Cabrillo Point (Grassland)

This list may not be complete but is based on published studies.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: Probably in the low hundreds, however, until new EOSPECs are put in use, or more nests areas mapped, this is uncertain.

10,000 to >1,000,000 individuals

Comments: Most recent population estimate is 5,842-11,330 compiled by Olendorff (1993). However, Schmutz et al. (1992) estimated 14,000 for the Great Plains alone. Estimated population in Canada in the early 1990s was 2000-4000 breeding pairs (Schmutz, 1994 COSEWIC report, cited by Jensen 1995). Between year movements of population centers and individuals makes estimation of actual abundance difficult.

More info for the terms: cover, shrubs

The ferruginous hawk occurs in the following major fire-dependent plant
associations in the western United States: grassland, semidesert
grass-shrub, sagebrush-grass, and pinyon-juniper [15].

In addition to potentially affecting nest trees, fire may affect the
prey base and hunting efficiency of ferruginous hawks. Many ferruginous
hawk prey species are affected by any disturbance that changes the
balance between understory cover and forage. Regular burning helps to
keep habitats in a suitable condition for many prey species of the
ferruginous hawk and temporarily exposes the prey when cover is reduced
[14]. In the past, fires have contributed to the maintenance of
grasslands by retarding woody growth. The exclusion of fire in this
ecosystem has resulted in encroachment of trees and shrubs which has had
a negative affect on the ferruginous hawk [15,21]. Ferruginous hawks
are favored by fires that reduce pinyon-juniper woodlands. Removing
some of these trees enhances the prey base by improving habitat for
small mammals [10]. Additionally, fires may remove thickets that limit
the hunting efficiency of ferruginous hawks [14]. Low-severity fires
may thin nest trees and enhance hunting nearby.

Age at sexual maturity - Most ferruginous hawks become sexually mature
at 2 years of age [5].

Breeding season - The ferruginous hawk generally returns to breeding
grounds in late March or early April [24] and begin nest construction in
April [5]. Breeding pairs aggressively defend their nesting territory.
Nests are frequently reused by the same pair in subsequent years [24].

Clutch size and incubation - The ferruginous hawk generally lays three
to four eggs in April but this number varies with fluctuating food
supply. The eggs are incubated for 28 to 36 days [5,21]. Incubation is
shared by both sexes [5,21]. The ferruginous hawk generally will not
lay a replacement clutch or renest if disturbed [21].

Fledging - Male nestlings fledge at 38 to 40 days. The females, which
are heavier and develop more slowly, fledge about 10 days later [21].

Fall migration - Migration generally begins in late September through
early October, with the onset of cold weather [21].

Spring migration - Ferruginous hawks usually arrive in the northern tier
of states from late March through early April. The yearling ferruginous
hawks arrive in May through early June [21].

Longevity - The maximum potential longevity for the ferruginous hawk is
about 20 years [21].

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).

Comments: Hunts most frequently near sunrise and sunset (Evans 1982).

Range lifespan
Status: wild: 20 (high) years.

Average lifespan
Status: wild: 284 months.

Maximum longevity: 23.7 years (wild) Observations: Maximum longevity from banding studies is 23.7 years (http://www.pwrc.usgs.gov/BBL/homepage/longvrec.htm).

Ferruginous Hawks tend to breed in open territory, plains, prairies, and badlands. Nests are built on low cliffs, buttes, cut banks, shrubs, or trees, and occasionally on man-made structures or the ground. Sticks 2.5cm (1in.) in diameter, cow dung, bones, and grass are used in construction of nests. Ferruginous Hawks have a clutch of 2-6 eggs that are bluish white, marked with brown. The average size of the egg is 2.4" (61mm). The eggs are fertilized and laid in April, and incubate for approximately 28 days. Young fledge within 38-50 days. The parents share the responsibility of feeding the young until they become independent, usually after 30 to 60 days (Ehrich 1988; Clark 1987).

Average time to hatching: 32 days.

Average eggs per season: 3.

Average age at sexual or reproductive maturity (male)
Sex: male: 730 days.

Average age at sexual or reproductive maturity (female)
Sex: female: 730 days.

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.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There is 1 barcode sequence available from BOLD and GenBank.   Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen.  Other sequences that do not yet meet barcode criteria may also be available.

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Barcode of Life Data Systems (BOLDS) Stats
Public Records: 1
Specimens with Barcodes: 2
Species With Barcodes: 1

Information on state- and province-level protection status of animals in the
United States and Canada is available at NatureServe, although recent
changes in status may not be included.

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Least Concern
• 2004
  Near Threatened

Human agriculture and overgrazing have caused a great deal of disturbance in this hawk's nesting habitat. Many of these hawks have been shot while perched along roadsides. Federal law now protects all raptors, yet Ferruginous Hawks are still a species of special concern. In Washington Ferruginous Hawks are listed as Threatened (Leary 1998; Enrich 1988). They are also listed as near threatened by the IUCN.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: appendix ii

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N4B - Apparently Secure

United States

Rounded National Status Rank: N4B,N4N : N4B: Apparently Secure - Breeding, N4N: Apparently Secure - Nonbreeding

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Widespread and relatively common in the appropriate habitat. Reports of local declines, continued loss of habitat, sensitivity to disturbance in a prairie species, and relatively low numbers show this species should be carefully watched and regularly re-evaluated.

Population

Population Trend

Global Short Term Trend: Relatively stable (=10% change)

Comments: Local declines have been noted (e.g., Woffinden and Murphy 1989), but a widespread decline was not evident as of the early-1990s (USFWS 1992, Olendorff 1993). North American Breeding Bird Survey (BBS) data for the U.S. and Canada indicate a 13.5 percent increase from 1988 to 1989 and an average annual 0.5 percent increase for 1966-1989 (Droege and Sauer 1990). Wintering data from Christmas Bird Counts also indicate an increase in numbers from 1952-1984 (USFWS 1992). Schmutz (1995) reported that the range in Canada has been reduced by half, and that habitat within the range has been severely depleted and total numbers reduced by about 95 percent. Kirk et al. (1995) indicated that populations in Canada apparently are stable in available habitat. Jensen (1995) reported a recent range re-expansion in south-central Canada. Historically, very abundant in eastern Montana but numbers were lowered by the early 1900's (Allen 1874, Cameron 1914).

Major Threats

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: HABITAT LOSS: Some habitat has been lost due to agricultural development. Schmutz and Schmutz (1980) reported that habitat in the breeding range in Canada has been severely depleted by agriculture, disturbance, and forest invasion (see also Jensen 1995), though recent trends suggest relative stability (Schmutz 1995). Loss of grassland is not regarded as an immediate threat (USFWS 1992), but is likely a long-term threat (Olendorff 1993). Ability of native grasslands and shrublands to support viable populations may be compromised by the invasion of exotic annuals, especially cheatgrass (BROMUS TECTORUM) and Russian thistle (SALSOLA IBERICA). However, conversion of large areas of dense shrublands to grasslands may locally benefit Ferruginous Hawks. HUMAN DISTURBANCE: Easily disturbed during the breeding season (Olendorff 1973, Gilmer and Stewart 1983, Schmutz 1984, White and Thurow 1985, Bechard et al. 1990). Abandonment of nests occurs particularly in the early stages of nesting (Davy 1930, Weston 1968, Fitzner et al. 1977, Gilmer and Stewart 1983, White and Thurow 1985). In eastern Colorado, nests in remote locations had greater productivity compared to more accessible nests (Olendorff 1973). In South Dakota, the probability of fledging young was 11.4 percent greater in more remote nests than in nests within 2.47 kilometers of occupied buildings (Blair 1978). In North Dakota, avoided cropland and nesting within 0.7 kilometers of occupied buildings (Gaines 1985). In Alberta, rarely nested within 0.5 kilometers of farmyards (Schmutz 1984). In other instances, more tolerant of human disturbance. Nesting has occurred near active railroads and gravel roads (Rolfe 1896, Gilmer and Stewart 1983, MacLaren et al. 1988). Sensitivity to disturbance may be heightened in years of low prey abundance (White and Thurow 1985). Shooting may also be a threat, especially on the wintering grounds (Harmata 1981, Gilmer et al. 1985). Poisoning of prey species may be a threat both directly to hawks eating poisoned animals and indirectly through reduction of prey base, especially at prey concentration areas such as prairie dog colonies. Noted as an accidental but unsuitable host of the Brown-headed Cowbird (MOLOTHRUS ATER), an obligate brood parasite (Friedmann 1963).

More info for the terms: cover, density, tree

The ferruginous hawk requires large tracts of relatively undisturbed
areas [5]. The conversion of extensive tracts of native vegetation into
monotypic stands for grazing and agriculture may reduce ferruginous hawk
densities and reproductive success. Reductions may be due to decreased
availability of major prey, loss of nest sites, and increased human
disturbance [3,10,11].

The ferruginous hawk is vulnerable to tree removal. Peripheral trees
should be left during tree removal and chaining operations to provide
nest sites. Isolated trees can be protected by fenced enclosures. Loss
of isolated trees can be remediated by artificial nest structures [11].

Maximum consideration should be afforded this species when range
development is planned [3]. Land management practices that dramatically
alter the density and structure of native vegetation can adversely
affect both jackrabbit and alternate prey populations, resulting in a
reduction in breeding ferruginous hawks. Range management practices
that support abundant and diverse prey may provide suitable food
alternatives for the ferruginous hawk during periods of jackrabbit
decline [11].

Conversion of extensive tracts of brushland and native vegetation to
either agriculture or monotypic fields of grass is particularly
disruptive to jackrabbits and cottontails [11,33]. Areas providing an
interspersion of tall cover and open spaces are preferred by
jackrabbits. Moderate amounts of rangeland and agricultural land
support pocket gophers and ground squirrels, which may provide alternate
prey species for the ferruginous hawk [11]. Although overgrazed areas
may temporarily provide vulnerable prey, it is unlikely that such areas
will support an adequate prey base for any length of time [11].
Additionally, severe overgrazing could affect ferruginous hawk nest site
selection by causing a decline in the regeneration of willows [5].

Vegetation management for the ferruginous hawk should emphasize
maximizing the amount of edge and interspersion of shrublands and
grasslands. Where Fairway wheatgrass plantings are planned, a minimum
of 20 percent of the area should be left in scattered islands of shrubby
vegetation. This design can produce optimum habitat for the ferruginous
hawk within 3 or 4 years after treatment [10].

The ferruginous hawk is very sensitive to human disturbance during the
nesting season and may abandon a nest during the pre-egg laying period
and incubation even if it is disturbed only once [5,11]. It is
important to time the implementation of range improvement activities to
avoid nesting periods. Late summer and fall are the optimum seasons for
range improvement practices in areas containing nests [3]. It is also
important to avoid range improvement activities in areas of high
ferruginous hawk foraging use [3,10].

Prescribed fire can be beneficial to ferruginous hawk populations by
providing an increased prey base of species that use burned areas
[3,10,14].

Conservation Actions

Preserve Selection and Design Considerations: LAND PROTECTION: Maintain ownership of public lands that have substantial numbers of hawks (Olendorff 1993). Protect large tracts of native prairie from conversion to monotypic stands of grass or other types of agriculture (Howard and Wolfe 1976, Lardy 1980, Schmutz 1991a, Bechard and Schmutz 1995). Avoid seeding of exotic grasses and cultivating of habitat, where possible (Janes 1985). Leave scattered islands of shrubby vegetation in crested wheatgrass fields so that the islands make up a minimum of 20 percent of the total area (Howard and Wolfe 1976).

Management Requirements: PREY CONSIDERATION: Increase grassland area to increase Richardson's ground squirrel (SPERMOPHILUS RICHARDSONII) abundance in Canada (Houston and Bechard 1984). Improve prey habitat by providing native shrub vegetation and increasing edge (Howard and Wolfe 1976, Bechard and Schmutz 1995). If brush is chained, windrow it to provide cover for prey (Olendorff 1993). When converting land from sagebrush steppe to herbaceous grassland (e.g., to crested wheatgrass), create a mosaic of treated (chained or disced) and untreated areas (Howard and Wolfe 1976). To attract small rodents, maintain or restore sagebrush-grass rangeland, removing pinyon pine (PINUS EDULUS)/Utah juniper stands (Howard and Wolfe 1976). If it is necessary to control lagomorph or rodent populations, try to lower the peaks of cyclic highs rather than completely exterminating them (Olendorff 1993).

REDUCE DISTURBANCE: Do not disturb nest sites from 15 March to 15 July (Howard and Wolfe 1976, Bechard and Schmutz 1995). Close public areas near nest sites to recreation during the breeding season (Lardy 1980) and close public land to firearms where dense populations of Ferruginous Hawks are particularly susceptible to shooting (Olendorff 1993). Establish buffer zones around nest sites and delay energy development until 45 days after fledging (Konrad and Gilmer 1986). White and Thurow (1985) recommended creating a buffer zone of 0.25 kilometers around nest sites. Atkinson (1992) suggested that a minimum distance of 0.45 kilometers be maintained from the nest. Olendorff (1993) suggested buffer zones of 0.25 kilometers for brief disturbances, 0.5 kilometers for intermittent activities, 0.8 kilometers for prolonged activities, and more than 1.0 kilometer for construction or similar activities. Provide information to ranchers, seismic crews, prospectors, and others to avoid disturbance to the nest (Atkinson 1992). Conduct treatments, e.g., chaining, discing, plowing, or burning, during the non-nesting season to avoid direct impacts to the hawks and their prey species during the reproductive season (Olendorff 1993). Generally, avoid treatments between 1 March and 1 August each year, especially during the incubation period when hawks are more prone to abandon nests if disturbed. Mitigate development impacts from mining, pipeline construction, and urbanization (Bechard and Schmutz 1995). Encourage rest-rotation or deferred-rotation grazing systems (Olendorff 1993). Delay grazing to allow for the completion of incubation (Atkinson 1992).

NEST STRUCTURES: Enhance, protect, and create nest substrates through fencing of nest trees, supporting heavy tree nests that are at risk of toppling, and building artificial nesting structures where nest sites are otherwise lacking (Olendorff 1973, Smith and Murphy 1978, Houston 1985, Bechard and Schmutz 1995, Leary et al. 1998). Other successful nest structure management techniques are to remove some of the previous year's nesting material to reduce the chance of toppling, realign the nest over a vertical axis, widen the base of the nest, reinforce the base of the nest using wire netting or other materials, move the nest to a safer location, or provide protection from predators by nailing tin sheathing around the tree base (Craig and Anderson 1979). In converting tree communities to grassland, provide nest sites by leaving individual trees, a mosaic of stands of trees, or a thin scattering of trees (Olendorff 1993). Leave poles and cross-arms of unused electrical lines for hunting perches (Olendorff 1993).

GRAZING: Grazing provides benefits by reducing vegetative cover and making prey more visible (Wakeley 1978, Konrad and Gilmer 1986). Kantrud and Kologiski (1982) found highest densities of Ferruginous Hawks in heavily grazed areas in the northern Great Plains. These areas provided a combination of grazing and soil type (typic borolls) that resulted in abundant prey populations (Kantrud and Kologiski 1982). In South Dakota, preferentially placed ground nests in lightly grazed pasture or idle areas (Lokemoen and Duebbert 1976, Blair 1978, Blair and Schitoskey 1982). In Saskatchewan, preferred grassland habitat exists in large blocks of government pastures located along the Montana and Alberta borders (Houston and Bechard 1984). These blocks of habitat are the only remaining areas with stable populations in Saskatchewan (Houston and Bechard 1984). Livestock, however, can weaken nest trees by excessive rubbing or trampling (Houston 1982, Olendorff 1993). Bock et al. (1993) suggested negative response to grazing in shrubsteppe habitats, based on the ground cover requirements of their prey.

Biological Research Needs: Understanding of the wintering ecology, dispersal, site fidelity (breeding and winter), and possible differences between subpopulations east and west of the Rocky Mountains is needed for conservation planning. Other research needs include basic biology, color polymorphism, nomadism, and relationship between populations of hawks and prey, especially cyclic species. The effects of management actions and strategies on Ferruginous hawks is also poorly known (Bechard and Schmutz 1995).

Global Protection: Few to very many (1 to >40) occurrences appropriately protected and managed

Comments: One protected at Kevin Rim by BLM as an ACEC (Area of Critical Environmental Concern). Eight Key Raptor Areas are managed by BLM in Montana (Centennial Valley, Lima Foothills, Madison river, Sweetwater Breaks, Kevin Rim, Rocky Mountain East Front, Rock Creek-Thoeny Area, and Lone Tree Management Area).

Needs: Protect extensive areas of suitable habitat throughout the breeding and wintering range; protect concentrated prey sources such as prairie dog towns.

Ferruginous Hawks may be a problem for farmers, as they will occasionally prey upon chickens.

Ferruginous Hawks help to keep the rodent population in check.

Stewardship Overview: Conversion of grasslands to intensive cultivation has reduced the amount of preferred habitat that is available and has been implicated in the population decline of the species in some areas (Schmutz 1984, Faanes and Lingle 1995). Agricultural development has restricted the species to areas of greater topographic relief or other areas unsuitable for agriculture (Stewart 1975). Keys to management are providing suitable nest sites, protecting active nest areas from disturbance, and improving habitat for prey. Isolated trees and stringers should be protected from livestock in nesting habitat. Prescribed burning may increase habitat suitability in shrub-dominated areas. Practices that increase exotic plant species number or dominance should be discouraged. Artificial nests have been used to increase number of nesting pairs in areas where suitable sites are scarce (Schmutz 1984).