Buteo regalis - (Gray, 1844)
Ferruginous Hawk
Other English Common Names: ferruginous hawk
Taxonomic Status: Accepted
Related ITIS Name(s): Buteo regalis (Gray, 1844) (TSN 175377)
French Common Names: buse rouilleuse
Spanish Common Names: Aguililla Real
Unique Identifier: ELEMENT_GLOBAL.2.103222
Element Code: ABNKC19120
Informal Taxonomy: Animals, Vertebrates - Birds - Other Birds
Image 10666

© Dick Cannings

 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Aves Accipitriformes Accipitridae Buteo
Genus Size: D - Medium to large genus (21+ species)
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Concept Reference
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Concept Reference: American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Concept Reference Code: B98AOU01NAUS
Name Used in Concept Reference: Buteo regalis
Conservation Status
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NatureServe Status

Global Status: G4
Global Status Last Reviewed: 06Apr2016
Global Status Last Changed: 22Nov1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: 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.
Nation: United States
National Status: N4B,N4N (05Jan1997)
Nation: Canada
National Status: N3B,N3N,NUM (01Dec2017)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Arizona (S2B,S4N), California (S3S4), Colorado (S3B,S4N), Idaho (S3B), Kansas (S2B,S4N), Minnesota (SNA), Montana (S3B), Navajo Nation (S2S3B,S3N), Nebraska (S2), Nevada (S2), New Mexico (S2B,S4N), North Dakota (SU), Oklahoma (SU), Oregon (S3B), South Dakota (S4B), Texas (S2B,S4N), Utah (S3B), Washington (S2B), Wyoming (S4B,S5N)
Canada Alberta (S2S3B), British Columbia (SNRN), Manitoba (S1S2B), Saskatchewan (S4B,S4M)

Other Statuses

Canadian Species at Risk Act (SARA) Schedule 1/Annexe 1 Status: T (23Feb2010)
Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Threatened (25Apr2008)
Comments on COSEWIC: Reason for designation: This large hawk is found primarily on natural grasslands in southern Alberta, Saskatchewan and Manitoba and is a specialist predator on Richardson's Ground Squirrels. It suffered a 64% decline in population from 1992 to 2005; since Alberta comprises the majority of the Canadian range, this implies a decline of at least 30% across the prairies over that time period. The loss, degradation and fragmentation of its native grassland habitat are the most serious threats to the population.

Status history: Designated Threatened in April 1980. Status re-examined and designated Special Concern in April 1995. Status re-examined and designated Threatened in April 2008.

IUCN Red List Category: LC - Least concern
Convention on International Trade in Endangered Species Protection Status (CITES): Appendix II

NatureServe Global Conservation Status Factors

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

Number of Occurrences: 81 to >300
Number of Occurrences Comments: Probably in the low hundreds, however, until new EOSPECs are put in use, or more nests areas mapped, this is uncertain.

Population Size: 10,000 to >1,000,000 individuals
Population Size 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.

Overall Threat Impact 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).

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend 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).

Other NatureServe Conservation Status Information

Inventory Needs: Obtain up-to-date information on range-wide distribution and abundance including during the non-breeding season.

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

Distribution
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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).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
NOTE: The maps for birds represent the breeding status by state and province. In some jurisdictions, the subnational statuses for common species have not been assessed and the status is shown as not-assessed (SNR). In some jurisdictions, the subnational status refers to the status as a non-breeder; these errors will be corrected in future versions of these maps. A species is not shown in a jurisdiction if it is not known to breed in the jurisdiction or if it occurs only accidentally or casually in the jurisdiction. Thus, the species may occur in a jurisdiction as a seasonal non-breeding resident or as a migratory transient but this will not be indicated on these maps. See other maps on this web site that depict the Western Hemisphere ranges of these species at all seasons of the year.
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AZ, CA, CO, ID, KS, MN, MT, ND, NE, NM, NN, NV, OK, OR, SD, TX, UT, WA, WY
Canada AB, BC, MB, SK

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: WILDSPACETM 2002


U.S. Distribution by County Help
State County Name (FIPS Code)
AZ Apache (04001), Coconino (04005), Mohave (04015), Navajo (04017), Yavapai (04025)
CA Alameda (06001), Contra Costa (06013), Imperial (06025), Kern (06029), Los Angeles (06037), Merced (06047), Monterey (06053), Napa (06055), Orange (06059), Riverside (06065), Sacramento (06067), San Diego (06073), San Joaquin (06077), San Luis Obispo (06079), Santa Barbara (06083), Siskiyou (06093), Solano (06095), Sonoma (06097), Ventura (06111)
CO Adams (08001), Alamosa (08003), Arapahoe (08005), Baca (08009), Bent (08011), Boulder (08013), Broomfield (08014), Cheyenne (08017), Conejos (08021)*, Costilla (08023), Crowley (08025), El Paso (08041), Elbert (08039), Garfield (08045), Huerfano (08055), Jefferson (08059), Kiowa (08061), Kit Carson (08063), Larimer (08069), Las Animas (08071), Lincoln (08073), Logan (08075), Mesa (08077), Moffat (08081), Otero (08089), Park (08093), Prowers (08099), Pueblo (08101), Rio Blanco (08103), Washington (08121), Weld (08123), Yuma (08125)
ID Ada (16001), Adams (16003), Bannock (16005), Bear Lake (16007), Bingham (16011), Blaine (16013), Bonneville (16019), Butte (16023), Camas (16025), Canyon (16027), Caribou (16029), Cassia (16031), Clark (16033), Custer (16037), Elmore (16039), Franklin (16041), Fremont (16043), Gem (16045), Gooding (16047), Idaho (16049)*, Jefferson (16051), Jerome (16053), Latah (16057), Lemhi (16059), Lincoln (16063), Madison (16065), Minidoka (16067), Nez Perce (16069), Oneida (16071), Owyhee (16073), Payette (16075), Power (16077), Teton (16081), Twin Falls (16083), Valley (16085), Washington (16087)
KS Cheyenne (20023), Finney (20055), Gove (20063), Greeley (20071), Lane (20101), Logan (20109), Meade (20119), Morton (20129), Scott (20171), Sherman (20181), Trego (20195), Wallace (20199), Wichita (20203)
MT Beaverhead (30001), Blaine (30005), Broadwater (30007), Carter (30011), Cascade (30013), Chouteau (30015), Custer (30017), Daniels (30019), Dawson (30021), Fallon (30025), Fergus (30027), Gallatin (30031), Garfield (30033), Glacier (30035), Golden Valley (30037), Hill (30041), Jefferson (30043), Judith Basin (30045), Lewis and Clark (30049), Liberty (30051), Madison (30057), McCone (30055), Meagher (30059), Musselshell (30065), Park (30067), Petroleum (30069), Phillips (30071), Pondera (30073), Powder River (30075), Prairie (30079), Roosevelt (30085), Rosebud (30087), Sheridan (30091), Stillwater (30095), Teton (30099), Toole (30101), Valley (30105), Wheatland (30107), Wibaux (30109), Yellowstone (30111)
ND Stark (38089), Walsh (38099)*
NE Banner (31007), Box Butte (31013), Cherry (31031), Cheyenne (31033), Dawes (31045), Dundy (31057), Grant (31075), Hayes (31085), Hooker (31091), Kearney (31099), Kimball (31105), Lincoln (31111), Morrill (31123), Sheridan (31161), Sioux (31165)
NM Catron (35003), Colfax (35007), Curry (35009), Dona Ana (35013), Mckinley (35031), Otero (35035), Quay (35037), San Juan (35045), Santa Fe (35049), Socorro (35053)
NV Churchill (32001), Elko (32007), Eureka (32011), Humboldt (32013), Lander (32015), Lincoln (32017), Nye (32023), Pershing (32027), White Pine (32033)
OK Beaver (40007), Cimarron (40025), Comanche (40031), Ellis (40045), Grady (40051), Grant (40053), Harper (40059), Jefferson (40067), McClain (40087), Texas (40139), Tillman (40141), Washita (40149), Woods (40151)
OR Baker (41001), Gilliam (41021)*, Harney (41025), Malheur (41045), Morrow (41049), Umatilla (41059), Union (41061), Wallowa (41063)
SD Beadle (46005), Bennett (46007)*, Brown (46013), Butte (46019), Corson (46031), Fall River (46047), Faulk (46049), Hand (46059), Harding (46063), Hyde (46069), Lyman (46085), McPherson (46089), Meade (46093), Pennington (46103), Perkins (46105), Potter (46107), Roberts (46109), Spink (46115), Stanley (46117), Sully (46119), Walworth (46129)
TX Lubbock (48303), Moore (48341)
UT Beaver (49001), Box Elder (49003), Carbon (49007), Davis (49011)*, Duchesne (49013), Emery (49015), Grand (49019), Iron (49021), Juab (49023), Kane (49025)*, Millard (49027), Morgan (49029)*, Piute (49031), Rich (49033), Salt Lake (49035)*, Sanpete (49039), Sevier (49041)*, Summit (49043)*, Tooele (49045), Uintah (49047), Utah (49049), Wasatch (49051)*, Washington (49053), Wayne (49055)*
WA Adams (53001), Benton (53005), Columbia (53013), Franklin (53021), Garfield (53023), Grant (53025), Kittitas (53037), Klickitat (53039), Lincoln (53043), Spokane (53063), Walla Walla (53071), Whitman (53075), Yakima (53077)
WY Albany (56001), Big Horn (56003), Campbell (56005), Carbon (56007), Converse (56009), Crook (56011), Fremont (56013), Goshen (56015), Hot Springs (56017), Johnson (56019), Laramie (56021), Lincoln (56023), Natrona (56025), Niobrara (56027), Park (56029), Platte (56031), Sheridan (56033), Sublette (56035), Sweetwater (56037), Teton (56039), Uinta (56041), Washakie (56043), Weston (56045)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
09 Park (09020310)+*
10 Red Rock (10020001)+, Beaverhead (10020002)+, Ruby (10020003)+, Big Hole (10020004)+, Jefferson (10020005)+, Madison (10020007)+, Gallatin (10020008)+*, Upper Missouri (10030101)+, Upper Missouri-Dearborn (10030102)+, Smith (10030103)+, Sun (10030104)+, Belt (10030105)+, Cut Bank (10030202)+, Marias (10030203)+, Willow (10030204)+, Teton (10030205)+, Bullwhacker-Dog (10040101)+, Arrow (10040102)+, Judith (10040103)+, Fort Peck Reservoir (10040104)+, Big Dry (10040105)+, Little Dry (10040106)+, Upper Musselshell (10040201)+, Middle Musselshell (10040202)+, Flatwillow (10040203)+, Box Elder (10040204)+, Lower Musselshell (10040205)+, Milk Headwaters (10050001)+, Upper Milk (10050002)+, Wild Horse Lake (10050003)+, Middle Milk (10050004)+, Big Sandy (10050005)+, Sage (10050006)+, Lodge (10050007)+, Battle (10050008)+, Peoples (10050009)+, Cottonwood (10050010)+, Whitewater (10050011)+, Lower Milk (10050012)+, Beaver (10050014)+, Rock (10050015)+, Porcupine (10050016)+, Prarie Elk-Wolf (10060001)+, Redwater (10060002)+, Poplar (10060003)+, West Fork Poplar (10060004)+, Big Muddy (10060006)+, Brush Lake closed basin (10060007)+, Shields (10070003)+, Upper Yellowstone-Lake Basin (10070004)+, Clarks Fork Yellowstone (10070006)+, Upper Yellowstone-Pompeys Pillar (10070007)+, Upper Wind (10080001)+, Little Wind (10080002)+, Popo Agie (10080003)+, Muskrat (10080004)+, Lower Wind (10080005)+, Badwater (10080006)+, Upper Bighorn (10080007)+, Nowood (10080008)+, Greybull (10080009)+, Big Horn Lake (10080010)+, Dry (10080011)+, North Fork Shoshone (10080012)+, South Fork Shoshone (10080013)+, Shoshone (10080014)+, Upper Tongue (10090101)+, Middle Fork Powder (10090201)+, Upper Powder (10090202)+, South Fork Powder (10090203)+, Salt (10090204)+, Crazy Woman (10090205)+, Clear (10090206)+, Middle Powder (10090207)+, Little Powder (10090208)+, Lower Powder (10090209)+, Lower Yellowstone-Sunday (10100001)+, Lower Yellowstone (10100004)+, O'fallon (10100005)+, Upper Little Missouri (10110201)+, Boxelder (10110202)+, Beaver (10110204)+, Antelope (10120101)+, Dry Fork Cheyenne (10120102)+, Upper Cheyenne (10120103)+, Lance (10120104)+, Lightning (10120105)+, Angostura Reservoir (10120106)+, Beaver (10120107)+, Hat (10120108)+, Cherry (10120113)+, Upper Belle Fourche (10120201)+, Lower Belle Fourche (10120202)+, Redwater (10120203)+, Upper Lake Oahe (10130102)+, Lower Lake Oahe (10130105)+, West Missouri Coteau (10130106)+, Upper Heart (10130202)+, North Fork Grand (10130301)+, South Fork Grand (10130302)+, Grand (10130303)+, South Fork Moreau (10130304)+, Upper Moreau (10130305)+, Fort Randall Reservoir (10140101)+, Bad (10140102)+, Medicine Knoll (10140103)+, Medicine (10140104)+, Crow (10140105)+, Upper White (10140201)+, Middle White (10140202)+, Little White (10140203)+*, Niobrara Headwaters (10150002)+, Upper Niobrara (10150003)+, Middle Niobrara (10150004)+, Elm (10160004)+, Middle James (10160006)+, East Missouri Coteau (10160007)+, Snake (10160008)+, Turtle (10160009)+, Middle Big Sioux Coteau (10170201)+, Upper North Platte (10180002)+, Pathfinder-Seminoe Reservoirs (10180003)+, Medicine Bow (10180004)+, Little Medicine Bow (10180005)+, Sweetwater (10180006)+, Middle North Platte-Casper (10180007)+, Glendo Reservoir (10180008)+, Middle North Platte-Scotts Bluff (10180009)+, Upper Laramie (10180010)+, Lower Laramie (10180011)+, Horse (10180012)+, Pumpkin (10180013)+, Lower North Platte (10180014)+, South Platte Headwaters (10190001)+, Middle South Platte-Cherry Creek (10190003)+, Clear (10190004)+, St. Vrain (10190005)+, Cache La Poudre (10190007)+, Lone Tree-Owl (10190008)+, Crow (10190009)+, Kiowa (10190010)+, Bijou (10190011)+, Middle South Platte-Sterling (10190012)+, Beaver (10190013)+, Pawnee (10190014)+, Upper Lodgepole (10190015)+, Lower Lodgepole (10190016)+, Sidney Draw (10190017)+, Upper Middle Loup (10210001)+, Upper North Loup (10210006)+*, Arikaree (10250001)+, North Fork Republican (10250002)+, South Fork Republican (10250003)+, Upper Republican (10250004)+, Frenchman (10250005)+, Red Willow (10250007)+, Medicine (10250008)+, Upper Sappa (10250010)+, Smoky Hill Headwaters (10260001)+, Upper Smoky Hill (10260003)+, Ladder (10260004)+, Hackberry (10260005)+, Upper Little Blue (10270206)+
11 Upper Arkansas (11020002)+, Fountain (11020003)+, Chico (11020004)+, Upper Arkansas-Lake Meredith (11020005)+, Huerfano (11020006)+, Apishapa (11020007)+, Horse (11020008)+, Upper Arkansas-John Martin (11020009)+, Purgatoire (11020010)+, Big Sandy (11020011)+, Two Butte (11020013)+, Middle Arkansas-Lake Mckinney (11030001)+, Whitewoman (11030002)+, Pawnee (11030005)+, Cimarron headwaters (11040001)+, Upper Cimarron (11040002)+, North Fork Cimarron (11040003)+, Sand Arroyo (11040004)+, Bear (11040005)+, Upper Cimarron-Liberal (11040006)+, Lower Cimarron-Eagle Chief (11050001)+, Lower Salt Fork Arkansas (11060004)+, Cimarron (11080002)+, Rita Blanca (11090103)+, Upper Beaver (11100101)+, Middle Beaver (11100102)+, Coldwater (11100103)+, Palo Duro (11100104)+, Lower Beaver (11100201)+, Lower Wolf (11100203)+, Tierra Blanca (11120101)+, Blue-China (11130102)+, Cache (11130202)+, West Cache (11130203)+, Northern Beaver (11130208)+, Upper Washita (11130302)+, Middle Washita (11130303)+
12 Yellow House Draw (12050001)+, North Fork Double Mountain Fork (12050003)+, Running Water Draw (12050005)+
13 Alamosa-Trinchera (13010002)+, San Luis (13010003)+, Upper Rio Grande (13020101)+, Arroyo Chico (13020205)+, Plains of San Agustin (13020208)+, Rio Salado (13020209)+, Jornada Del Muerto (13020210)+, Western Estancia (13050001)+, Tularosa Valley (13050003)+, Taiban (13060004)+
14 Colorado headwaters-Plateau (14010005)+, Westwater Canyon (14030001)+, Lower Dolores (14030004)+, Upper Colorado-Kane Springs (14030005)+, Upper Green (14040101)+, New Fork (14040102)+, Upper Green-Slate (14040103)+, Big Sandy (14040104)+, Bitter (14040105)+, Upper Green-Flaming Gorge Reservoir (14040106)+, Blacks Fork (14040107)+, Muddy (14040108)+, Vermilion (14040109)+, Great Divide closed basin (14040200)+, Little Snake (14050003)+, Muddy (14050004)+, Upper White (14050005)+, Lower White (14050007)+, Lower Green-Diamond (14060001)+, Ashley-Brush (14060002)+, Duchesne (14060003)+, Lower Green-Desolation Canyon (14060005)+, Price (14060007)+, Lower Green (14060008)+, San Rafael (14060009)+, Muddy (14070002)+*, Fremont (14070003)+*, Paria (14070007)+*, Upper San Juan (14080101)+, Animas (14080104)+, Middle San Juan (14080105)+, Chaco (14080106)+, Chinle (14080204)+
15 Kanab (15010003)+*, Havasu Canyon (15010004)+, Hualapai Wash (15010007)+, Upper Virgin (15010008)+, Meadow Valley Wash (15010013)+, Carrizo Wash (15020003)+, Middle Little Colorado (15020008)+, Cottonwood Wash (15020011)+, Jadito Wash (15020014)+, Canyon Diablo (15020015)+, Lower Little Colorado (15020016)+, Dinnebito Wash (15020017)+, Burro (15030202)+, Big Chino-Williamson Valley (15060201)+
16 Upper Bear (16010101)+, Central Bear (16010102)+, Bear Lake (16010201)+, Middle Bear (16010202)+, Lower Bear-Malad (16010204)+, Upper Weber (16020101)+, Lower Weber (16020102)+*, Utah Lake (16020201)+, Provo (16020203)+*, Jordan (16020204)+*, Hamlin-Snake Valleys (16020301)+, Pine Valley (16020302)+, Tule Valley (16020303)+, Rush-Tooele Valleys (16020304)+, Skull Valley (16020305)+, Southern Great Salt Lake Desert (16020306)+, Pilot-Thousand Springs (16020307)+, Northern Great Salt Lake Desert (16020308)+, Curlew Valley (16020309)+, Great Salt Lake (16020310)+, Upper Sevier (16030001)+, East Fork Sevier (16030002)+*, Middle Sevier (16030003)+, San Pitch (16030004)+, Lower Sevier (16030005)+, Escalante Desert (16030006)+, Beaver Bottoms-Upper Beaver (16030007)+, Lower Beaver (16030008)+, Sevier Lake (16030009)+, Upper Humboldt (16040101)+, North Fork Humboldt (16040102)+, South Fork Humboldt (16040103)+, Pine (16040104)+, Middle Humboldt (16040105)+, Reese (16040107)+, Lower Humboldt (16040108)+, Little Humboldt (16040109)+, Upper Quinn (16040201)+, Lower Quinn (16040202)+, Granite Springs Valley (16050104)+, Carson Desert (16050203)+, Dixie Valley (16060001)+, Gabbs Valley (16060002)+, Southern Big Smoky Valley (16060003)+, Northern Big Smoky Valley (16060004)+, Diamond-Monitor Valleys (16060005)+, Little Smoky-Newark Valleys (16060006)+, Long-Ruby Valleys (16060007)+, Spring-Steptoe Valleys (16060008)+, Ralston-Stone Cabin Valleys (16060011)+, Hot Creek-Railroad Valleys (16060012)+
17 Upper Columbia-Entiat (17020010)+, Upper Crab (17020013)+, Lower Crab (17020015)+, Upper Columbia-Priest Rapids (17020016)+, Upper Yakima (17030001)+, Lower Yakima, Washington (17030003)+, Snake headwaters (17040101)+, Gros Ventre (17040102)+, Greys-Hobock (17040103)+, Palisades (17040104)+, Salt (17040105)+, Idaho Falls (17040201)+, Upper Henrys (17040202)+, Lower Henrys (17040203)+, Teton (17040204)+, Willow (17040205)+, American Falls (17040206)+, Blackfoot (17040207)+, Portneuf (17040208)+, Lake Walcott (17040209)+, Raft (17040210)+, Goose (17040211)+, Upper Snake-Rock (17040212)+, Salmon Falls (17040213)+, Beaver-Camas (17040214)+, Medicine Lodge (17040215)+, Birch (17040216)+, Little Lost (17040217)+, Big Lost (17040218)+, Big Wood (17040219)+, Camas (17040220)+, Little Wood (17040221)+, C. J. Idaho (17050101)+, Bruneau (17050102)+, Middle Snake-Succor (17050103)+, Upper Owyhee (17050104)+, South Fork Owyhee (17050105)+, Jordan (17050108)+, Lower Owyhee (17050110)+, Boise-Mores (17050112)+, South Fork Boise (17050113)+, Lower Boise (17050114)+, Middle Snake-Payette (17050115)+, Upper Malheur (17050116)+, Lower Malheur (17050117)+, Bully (17050118)+, Willow (17050119)+, Payette (17050122)+, North Fork Payette (17050123)+, Weiser (17050124)+, Brownlee Reservoir (17050201)+, Burnt (17050202)+, Powder (17050203)+, Imnaha (17060102)+, Wallowa (17060105)+, Lower Grande Ronde (17060106)+, Lower Snake-Tucannon (17060107)+, Palouse (17060108)+, Rock (17060109)+, Lower Snake (17060110)+, Pahsimeroi (17060202)+, Lemhi (17060204)+, Lower Salmon (17060209)+, Little Salmon (17060210)+*, Middle Columbia-Lake Wallula (17070101)+, Walla Walla (17070102)+, Umatilla (17070103)+, Willow (17070104)+*, Harney-Malheur Lakes (17120001)+, Donner Und Blitzen (17120003)+, Silver (17120004)+, Summer Lake (17120005)+, Guano (17120008)+
18 Russian (18010110)+, Butte (18010205)+, Lower Sacramento (18020163)+, Middle San Joaquin-Lower (18040001)+, San Joaquin Delta (18040003)+, Upper Merced (18040008)+, Upper Cosumnes (18040013)+, Suisun Bay (18050001)+, San Pablo Bay (18050002)+, San Francisco Bay (18050004)+, Carrizo Plain (18060003)+, Salinas (18060005)+, Central Coastal (18060006)+, Santa Ynez (18060010)+, Carmel (18060012)+, Santa Barbara Coastal (18060013)+, Santa Clara (18070102)+, Calleguas (18070103)+, Santa Monica Bay (18070104)+, San Gabriel (18070106)+, San Jacinto (18070202)+, Newport Bay (18070204)+, Santa Margarita (18070302)+, Antelope-Fremont Valleys (18090206)+, Whitewater River (18100201)+, San Felipe Creek (18100203)+, Salton Sea (18100204)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A carnivorous bird (hawk).
General Description: 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).
Diagnostic Characteristics: 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).
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).

Non-Migrant: N
Locally Migrant: Y
Long Distance Migrant: Y
Mobility and Migration Comments: 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).
Palustrine Habitat(s): Riparian
Terrestrial Habitat(s): Cliff, Desert, Grassland/herbaceous, Savanna
Habitat 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.

Adult Food Habits: Carnivore
Immature Food Habits: Carnivore
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).

Adult Phenology: Diurnal
Immature Phenology: Diurnal
Phenology Comments: Hunts most frequently near sunrise and sunset (Evans 1982).
Length: 58 centimeters
Weight: 1231 grams
Economic Attributes Not yet assessed
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Management Summary
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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).
Preserve Selection & 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).
Population/Occurrence Delineation
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Group Name: Hawks and Falcons

Use Class: Breeding
Subtype(s): Feeding Area, Nest Site
Minimum Criteria for an Occurrence: Evidence of historical breeding, or current and likely recurring breeding, at a given location, minimally a reliable observation of one or more breeding pairs in appropriate habitat. Be cautious about creating EOs for observations that may represent single breeding events outside the normal breeding distribution.
Mapping Guidance: If nest site is separated from feeding area by more than 100 meters, map as separate polygons.
Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 10 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Separation distance a compromise between usually relatively small home ranges and obvious mobility of these birds. Home ranges variable, ranging from about 0.5 to about 90 square kilometers; the latter figure refers to nests where birds commuted some distance to feeding grounds. A number of studies give mean home ranges on the order of 7 square kilometers, which equates to a circle with a diameter of about 3 kilometers; three times that home range gives a separation distance of about 10 kilometers. Home ranges: Ferruginous Hawk, mean 5.9 square kilometers in Utah (Smith and Murphy 1973); range 2.4 to 21.7 square kilometers, mean 7.0 square kilometers in Idaho (Olendorff 1993); mean 7.6 square kilometers in Idaho (McAnnis 1990); mean 90 square kilometers in Washington (Leary et al. 1998); Red-tailed Hawk, most forage within 3 kilometers of nest (Kochert 1986); mean spring and summer male home ranges 148 hectares (Petersen 1979); Hawaiian Hawk, 48 to 608 hectares (n = 16; Clarkson and Laniawe 2000); Zone-tailed Hawk, little information, apparent home range 1-2 kilometers/pair in west Texas (Johnson et al. 2000); White tailed Kite, rarely hunts more than 0.8 kilometers from nest (Hawbecker 1942); Prairie Falcon, 26 square kilometers in Wyoming (Craighead and Craighead 1956), 59 to 314 square kilometers (reported by Steenhof 1998); Aplomado Falcon, 2.6 to 9.0 square kilometers (n = 5, Hector 1988), 3.3 to 21.4 square kilometers (n = 10, Montoya et al. 1997). Nest site fidelity: high in Zone-tailed Hawk; all seven west Texas nesting territories occupied in 1975 were reused in 1976 (Matteson and Riley 1981). Swainson's Hawk: In California, dispersal distances from natal sites to subsequent breeding sites ranged from 0 to 18 kilometers, mean 8.8 kilometers (Woodbridge et al. 1995); in contrast, none of 697 nestlings in Saskatchewan returned to the study area; three were found 190, 200 and 310 kilometers away (Houston and Schmutz 1995).
Inferred Minimum Extent of Habitat Use (when actual extent is unknown): 3 km
Inferred Minimum Extent Justification: Foraging range variable; 3 kilometers is the mean diameter in several species.
Date: 13Mar2001
Author: Cannings, S.

Use Class: Nonbreeding
Subtype(s): Foraging area, Roosting area
Minimum Criteria for an Occurrence: Evidence of recurring presence of wintering birds (including historical); and potential recurring presence at a given location, usually minimally a reliable observation of 5 birds (this can be reduced to 1 individual for rarer species). Occurrences should be locations where the species is resident for some time during the appropriate season; it is preferable to have observations documenting presence over at least 20 days annually. Be cautious about creating EOs for observations that may represent single events.
Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 10 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Separation distance somewhat arbitrary; set at 10 kilometers to define occurrences of managable size for conservation purposes. However, occurrences defined primarily on the basis of areas supporting concentrations of foraging birds, rather than on the basis of distinct populations.
Date: 15Apr2002
Author: Cannings, S.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 11Dec1995
NatureServe Conservation Status Factors Author: Reichel, J.D. and E.C. Atkinson. Partially revised/updated by G. Hammerson.
Management Information Edition Date: 01Jan1999
Management Information Edition Author: DECHANT, J.A., M.L. SONDREAL, D.H. JOHNSON, L.D. IGL, C.M. GOLDADE, A.L. ZIMMERMAN, B.R. EULISS; REVISIONS BY J.D. REICHEL, E.C. ATKINSON, G. HAMMERSON, M. KOENEN, AND D.W. MEHLMAN
Management Information Acknowledgments: Parts of this abstract were originally researched and written by staff of the Northern Prairie Wildlife Research Center and published as Dechant et al. (1999). Additional support for the preparation of this abstract was provided by the National Fish and Wildlife Foundation's Neotropical Migratory Bird Conservation Initiative, through challenge grant number 97-270 to The Nature Conservancy, Wings of the Americas Program. Matching funds for this grant were donated by Canon U.S.A., Inc.
Element Ecology & Life History Edition Date: 29Mar1995
Element Ecology & Life History Author(s): HAMMERSON, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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