Ferruginous Hawk - Buteo regalis
Ferruginous Hawks have rusty backs and shoulders, pale heads, and white tails washed with pale rust. They have a white patch at the base of the flight feathers on the upper wing surface. Their wings are brown above and white below. The rusty legs of the adult form a dark V contrasted with whitish underparts. Ferruginous Hawks usually appear very light-colored when viewed from a distance. The uncommon dark phase lacks dark tail bands and are dark brown on the body, but still have the whitish tail. The species averages 58 cm long with a 135 cm wingspan. Immature birds are brown instead of rust, and have brown streaking on the undersides.
Krider's Red-tailed Hawk (B. jamaicensis) is brown, not rust, has white feathers on the legs, dark shoulder patches, and a dark band across the belly. The dark phase Ferruginous Hawk differs from the dark phase Rough-legged Hawk (B. lagopus) by the absence of dark tail bands in the former. Immature Ferruginous Hawks resemble the Great Plains form of the Red-tailed Hawk, but have larger white wing patches and lack the dark bar on the leading edge of the underwing.
Western Hemisphere Range
Summary of Observations Submitted for Montana
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(direct evidence "B")
(indirect evidence "b")
No evidence of Breeding
(regular observations "W")
(at least one obs. "w")
(Records associated with a range of dates are excluded from time charts)
Ferruginous Hawks breeding in Montana are entirely migratory (Bechard and Schmutz 1995). Fall migration begins in August and continues into early September. Young birds will migrate south earlier than, and independent of, adults. The latest recorded observation date for Ferruginous Hawks in eastern Montana is in October, from 3 records (Saunders 1921, Montana Bird Distribution Committee 2012). Most will move southeast, then south following grasslands (Schmutz and Fyfe 1987) to wintering locations in Texas and northern Mexico (Bechard and Schmutz 1995). Although historical records (Saunders 1921) indicate Ferruginous Hawks did overwinter in the state around the turn of the 19th century, it is not believed they currently do so. Birds from the western subpopulation apparently migrate into extreme western Montana from eastern Washington and Oregon, although only a handful of records exist and there are only three documented overwintering occurrences (see Distribution). Ferruginous Hawks begin arriving in southeastern Montana in mid- to late March (Wittenhagen 1992). Restani (1991) reported most returns to the Centennial Valley occurring in April and May. Most spring observations in the Montana Bird Distribution (2012) database are in April and May as well.
The habitat of Ferruginous Hawks in Montana has been studied extensively (Ensign 1983, Restani 1989, 1991, De Velice 1990, Wittenhagen 1992, Black 1992, Atkinson 1992, 1993) and described as mixed-grass prairie, shrub-grasslands, grasslands, grass-sagebrush complex, and sagebrush steppe. In southeastern Montana, Ensign (1983) reported mixed-grass prairie with black greasewood (Sarcobatus vermiculatus) and big sagebrush (Artemisia tridentata) in uplands and drainages. Other shrub and tree species present in the habitat were junipers (Juniperus ssp.), cottonwoods (Populus ssp), willows (Salix spp.), and ponderosa pine (Pinus ponderosa). Also in southeastern Montana, Wittenhagen (1992) reported Ferruginous Hawk habitat to consist of shrub-grasslands with big sagebrush present as well as wheatgrasses. The Kevin Rim area of north-central Montana has been categorized as grasslands dominated by bluebunch and western wheatgrass, blue gramma, and other grasses (De Velice 1990). Habitat also exists for Ferruginous Hawks in the Centennial Valley in the southwestern portion of the state. Restani (1989, 1991) reported grass-sagebrush complexes on mid-elevation slopes to be where most hawks nested. These complexes included sagebrush species and rabbitbrush as overstory to wheatgrasses, needle-and-thread grass, and junegrass. Also in southwestern Montana, Atkinson (1992, 1993) described the preferred habitat as sagebrush steppe over foothill prairie or mountain mahogany. Black (1992) surveyed Ferruginous Hawk habitat in Phillips County and reported the habitat to be 69% grassland, 25% shrubland and 13% bare area.
Nest location studies have also described the habitat Ferruginous Hawks use during the breeding season. 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 cultivated areas (20 percent) in north-central Montana, nests closer to cultivated fields and roads were more successful, presumably because of higher prey densities associated with edge habitats (Zelenak et al. 1997). 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). The average height of ground nests below the highest surrounding topographic feature was 10 meters, whereas the 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).
Ferruginous Hawks do not appear to nest in areas converted to agriculture (Schmutz 1984, Jasikoff 1982). A study done in Petroleum and Fergus counties seems to support this statement. Rogers and Rogers (1995) reported direct observations of Ferruginous Hawks avoiding crested wheatgrass (Agropyron cristatum) fields as nesting locations. They concluded few prey resources in such monotypic croplands as the reason for not nesting in these habitats.
Ecological Systems Associated with this Species
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (high, medium, or low) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2001, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
- Examining the observation records for each species in the state-wide point database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of “observations versus availability of habitat”.
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were associated as using an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignments of habitat quality.
If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at email@example.com
or (406) 444-3655.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species’ known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2001. The wild mammals of Montana. Special Publication No. 12. Lawrence, KS: The American Society of Mammalogists. 278 p.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana’s amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
- Commonly Associated with these Ecological Systems
Forest and Woodland Systems
Shrubland, Steppe and Savanna Systems
Sparse and Barren Systems
Wetland and Riparian Systems
In southeastern Montana White-tailed Jack Rabbits represent the greatest frequency (24.4%) and biomass of prey items, followed by Western Meadowlarks (18.3%), Thirteen-lined Ground Squirrels (12.7%), and Northern Pocket Gophers (11.7%) (Ensign 1983). In southwestern Montana (Restani 1991, Atkinson 1992) ground squirrels (S. armatus or S. elegans) were the most frequent food item (45 to 62%); other items greater than 10% included passerines, grasshoppers, and voles. Some studies in other areas of the species' range focused on vulnerability of prey. It 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).
In southeastern Montana, predation and sibling fratricide were the major causes of nestling mortality, accounting for 34 and 27%, respectively, of total progeny loss (Ensign 1983). Territories often contain alternate nests (Atkinson 1992). Distribution appears clumped, with large areas of apparently suitable habitat unoccupied (Atkinson 1992). Ecological information relating to home ranges of Ferruginous Hawks comes from studies throughout the west including Washington, Utah, and Idaho. Density varies with cycles of prey abundance and home ranges average between 3.14 km to 90.3 km.
Most reproduction studies in Montana have been done in four areas in the state: the southeastern, the southwestern, the Kevin Rim area in north-central Montana, and Phillips County. Ferruginous Hawks arrive in Montana in mid- to late March (Wittenhagen 1992). Ensign (1983) reported hawks already present when the field season began in early April. Wittenhagen (1992) recorded eggs being laid in mid-April. Ensign (1983) mentions eggs present by the third week of April in 1981 and the end of April in 1982. The average clutch size for Ferruginous Hawk nests in Montana ranges between 2.57 and 3.37 (Ensign 1983, Wittenhagen 1992). Ferruginous Hawk eggs hatch in late May (Wittenhagen 1992) and the first week of June (Ensign 1983). Fledging occurred in late June to mid-July and juvenile birds were observed into late August (Ensign 1983, Wittenhagen 1992). The average number of young fledged from four studies in the state ranges from 1.07 to 3.50 (Ensign 1983, Meyers 1987, Restani 1989, Wittenhagen 1992), with higher fledging success in the southwestern part of the state; more tree nesting and therefore fewer ground predators (Wittenhagen 1992). Once young birds have fledged, they have low mortality rates. Zelenak et al. (1997), working in the Kevin Rim region, reported an 86% percent survival rate of juvenile birds from fledging to 60 days later. No evidence exists for year-old birds breeding, but 2 year-olds do regularly (Bechard and Schmutz 1995).
The Kevin Rim area in north-central Montana supports a very dense population of breeding Ferruginous Hawks. DuBois (1988) reported 24 breeding pairs in an area of 23.5 square km, which translates to almost 60 pairs per 100 square mile. Black (1992) reports a likely population of 260 individuals in Phillips County, based on the number of hawk observations over a certain survey size. Meyers (1987), working in the Dillon area in southwestern Montana, documented one the densest Ferruginous Hawk populations in the state with 58 (1985) and 69 (1986) occupied territories in only 417 square miles.
In 1991, the Ferruginous Hawk was petitioned for listing under the Endangered Species Act (Ure et al. 1991). This petition was rejected due to insufficient data to warrant listing (U.S. Fish and Wildlife Service 1992). Ferruginous Hawks are not currently federally listed as a candidate or proposed species. The BLM in Montana identifies them as a sensitive species. Although no active management is currently in place for Ferruginous Hawks in Montana, other management plans do take this species into account. For example, Black-tailed Prairie Dog towns in the Judith-Valley-Phillips Resource Management Area are currently managed to help provide habitat for Ferruginous Hawks (Grensten 2002) as they use the dog towns for food and shelter. Ferruginous Hawks seem to accept and readily use artificial nest structures when placed in areas where populations have declined or where habitats lack suitable nest sites (Olendorff 1993). This practice would likely benefit Ferruginous Hawks in eastern Montana where nesting is primarily on the ground and nest structures would reduce predation (Wittenhagen 1992).
- Literature Cited AboveLegend: View WorldCat Record View Online Publication
- Atkinson, E. C. 1992. Ferruginous hawk (Buteo regalis) inventories on the Dillon Resource Area of southwest Montana: 1992. Montana Natural Heritage Program for Bureau of Land Management, Dillon Resource Area. 34 pp.
- Atkinson, E. C. 1993. Ferruginous hawk monitoring on the Dillon Resource Area of southwest Montana: 1993. Unpublished Report. Bureau of Land Management, Dillon, MT.
- Bechard, M. J. and J. K. Schmutz. 1995. Ferruginous hawk (Buteo regalis). In: A. Poole and F. Gill, eds. The Birds of North America, Number 172. The Academy of Natural Sciences, Philadelphia and The American Ornithologists' Union, Washington, D.C. 20 pp.
- Black, A. 1992. Ferruginous hawk reproduction and habitat survey. Unpublished report. Northern Rockies Conservation Cooperative, Jackson, WY. 13 pp.
- De Velice, R. L. 1990. Grassland and shrubland communities on USDI Bureau of Land Management lands in Montana: a proposal. Montana Natural Heritage Program, Helena, MT. 21 pp.
- Dubois, K. 1988. Kevin Rim/Sweetgrass Hills raptor survey. Bureau of Land Management. 8 pp. plus data appendices.
- Ensign, J. T. 1983. Nest site selection, productivity, and food habits of ferruginous hawks in southeastern Montana. M.S. thesis. Montana State University. 85 pp.
- Grensten, J. 2002. Black-footed ferret and prairie dog management. Online. Available: http://www.blm.gov/nhp/efoia/mt/2002/ib/02mtb061_at26.pdf. Accessed September 15, 2003.
- Houston, C. S. and M. J. Bechard. 1984. Decline of the ferruginous hawk in Saskatchewan. American Birds 38:166-170.
- Howard, R. P. and M. L. Wolfe. 1976. Range improvement practices and ferruginous hawks. Journal of Range Management 29(1):33-37.
- Jasikoff, T.M. 1982. Habitat suitability index models: ferruginous hawk. U.S.D.I. Fish and Wildlife Service FSW/OBS-82/10.10. 18 pp.
- Montana Bird Distribution Committee. 2012. P.D. Skaar's Montana bird distribution. 7th Edition. Montana Audubon, Helena, Montana. 208 pp. + foldout map.
- Myers, L.H. 1987. Nesting ecology of ferruginous hawks in Southwestern Montana. Paper presented at the Montana Nongame Symposium, Kalispell, MT. Feb. 11, 1987. 14 pp.
- Olendorff, R. R. 1993. Status, biology, and management of ferruginous hawks: a review. Raptor Research and Technical Assistance Center, Special Report U.S. Department of the Interior, Bureau of Land Management, Boise, ID. 84 pp.
- Restani, M. 1989. Resource partitioning among three species of hawks in the Centennial Valley, Montana. M.S. thesis. Montana State University, Bozeman. 86 pp.
- Restani, M. 1991. Resource partitioning among three Buteo species in the Centennial Valley, Montana. Condor 93:1007-1010.
- Rogers, R. and A. Rogers. 1995. Project report: a survey of nesting ferruginous hawks (Buteo regalis) on public lands in Petroleum and Fergus counties, Montana. Unpublished report to USDI Bureau of Land Management, Judith Resource Area, Lewistown, MT.
- Saunders, A. A. 1921. A distributional list of the birds of Montana. Pacific Coast Avifauna Number 14. 194 pp.
- Schmutz, J. K. 1984. Ferruginous and Swainson's hawk abundance and distribution in relation to land use in southeastern Alberta. Journal of Wildlife Management 48:1180-1187.
- Schmutz, J. K. 1987. The effect of agriculture on ferruginous and Swainson's hawks. Journal of Range Management 40(5):438-440.
- Schmutz, J. K. 1989. Hawk occupancy of disturbed grasslands in relation to models of habitat selection. Condor 91:362-371.
- Schmutz, J. K. and R. W. Fyfe. 1987. Migration and mortality of Alberta ferruginous hawks. Condor 89:169-174.
- U.S. Fish and Wildlife Service. 1992. Endangered and threatened wildlife and plants. Notice of finding on petition to list the Ferruginous Hawk. Federal Register 57(161):37507-37513.
- Ure, J., P. Briggs, and S.W. Hoffman. 1991. Petition to list as endangered the ferruginous hawk (Buteo regalis), as provide by the Endangered Species Act of 1973, as amended in 1982. Ferruginous Hawk Project, Salt Lake City, UT. 9 pp.
- Wakeley, J.S. 1978. Factors affecting the use of hunting sites by ferruginous hawks. Condor: 80:316-326.
- Wittenhagen, K. W. 1992. 1992 final report on the ferruginous hawk in southeastern Montana. Unpublished Report. U.S. Bureau of Land Management, Miles City, Montana. 31 pp.
- Zelenak, J. R., J. J. Rotella, and A. R. Harmata. 1997. Survival of fledgling ferruginous hawks in northern Montana. Canadian Journal of Zoology 75: 152-156.
- Additional ReferencesLegend: View WorldCat Record View Online Publication
Do you know of a citation we're missing?
- Abstracts from Montana Rare Animal Meeting. 1992. [November 5-6, 1992]. Lewistown, MT. 20 pp.
- Allen, G. T. 1979. An assessment of potential conflicts between nesting raptors and human activities in the Long Pines area of southeastern Montana with special emphasis on uranium development. M.S. thesis, Washington State University, Pullman. 109 pp.
- American Ornithologists' Union. 1998. Check-list of North American birds. 7th edition. American Ornithologists' Union, Washington, D.C. 829 pp.
- Atkinson, E. C. 1995. Survey and monitoring guidelines for Ferruginous Hawks in Montana. Bureau of Land Management and Montana Dept. Fish, Wildlife and Parks. 42 pp.
- Atkinson, E.G. 1992. Ferruginous Hawk Inventories on the Dillon Resource Area of southwest Montana, 1992. Mont. Nat. Heritage Prog., Helena 3 4 pp.
- Bechard, M. J. 1981. Historical nest records of the ferruginous hawk in Manitoba. Can. Field-Nat. 95: 467-469.
- Bechard, M. J., R. L. Knight, D. G. Smith, and R. E. Fitzner. 1990. Nest sites and habitats of sympatric hawks (BUTEO spp.) in Washington. J. Field Ornithol. 61:159-170.
- Bechard, Marc J., and Josef K. Schmutz. 1995. Ferruginous Hawk (Buteo regalis). Species Account Number 172. The Birds of North America Online (A. Poole, Ed.). Ithaca, NY: Cornell Laboratory of Ornithology; Retrieved 3/25/2008 from The Birds of North America Online database
- Becker, Dale M., 1980, A Survey of raptors on national forest land in Carter County, Montana. Final Progress Report: 1977-1979.
- Blair, C.L. 1978. Breeding biology and prey selection of Ferruginous Hawks in northwestern South Dakota. M.S. thesis. South Dakota State University, Brookings, SD. 60 pp.
- Blair, C.L., and F. Schitoskey Jr. 1982. Breeding biology and diet of the Ferruginous Hawk in South Dakota. Wilson Bulletin 94:46-54.
- Cameron, E. S. 1907. The birds of Custer and Dawson Counties, Montana. Auk 24(3):241-271.
- Cameron, E. S. 1914. The ferruginous rough-leg . . . in Montana. Auk 31: 159-167.
- Casey, D. 2000. Partners in Flight Draft Bird Conservation Plan Montana. Version 1.0. 287 pp.
- Clark, T. W., H.A. Harvey, R.D. Dorn, D.L. Genter, and C. Groves (eds). 1989. Rare, sensitive, and threatened species of the greater Yellowstone ecosystem. Northern Rockies Conservation Cooperative, Montana Natural Heritage Program, The Nature Conservancy, and Mountain West Environmental Services. 153 p.
- Davy, G.L. 1930. Nesting of the Ferruginous Roughleg Hawk in northern North Dakota. Oologist 47:14-18.
- De Smet, K.D., and M.P. Conrad. 1991. Status, habitat requirements, and adaptations of Ferruginous Hawks in Manitoba. Pages 219-221 in G.L. Holroyd, G. Burns, and H.C. Smith, editors. Proceedings of the second endangered species and prairie conservation workshop. Natural History Occasional Paper 15. Provincial Museum of Alberta, Edmonton, Alberta.
- Dechant, J. A., M. L. Sondreal, D. H. Johnson, L. D. Igl, C. M. Goldade, A. L. Zimmerman, and B. R. Euliss. 2003l. Effects of management practices on grassland birds: Ferruginous Hawk. Northern Prairie Wildlife Research Center, Jamestown, ND. Northern Prairie Wildlife Research Center
- Dobkin, D. S. 1992. Neotropical migrant landbirds in the Northern Rockies and Great Plains. U.S.D.A. For. Serv. N. Region Publ. R1-93-34. Missoula, Mont.
- Dobkin, D.S. 1994. Conservation and management of neotropical migrant landbirds in the Northern Rockies and Great Plains. Univ. Idaho Press, Moscow, Idaho. 220 pp.
- ECON, Inc. (Ecological Consulting Service), Helena, MT., 1979, Annual wildllife report of the Colstrip Area for 1978. Proj. 195-85-A. April 6, 1979.
- Econ, Inc., Helena, MT., 1978, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife and wildlife habitat monitoring study. Proj. 190-85-A. December 31, 1978.
- Econ, Inc., Helena, MT., 1991, Wildlife monitoring report: 1989 field season, Big Sky Mine. March 1991.
- Ehrlich, P., D. Dobkin, and D. Wheye. 1988. The birder’s handbook: a field guide to the natural history of North American birds. Simon and Schuster Inc. New York. 785 pp.
- Evans, D. L. 1982. Status reports on twelve raptors. U.S. Department of the Interior, Fish and Wildlife Service, Special Scientific Report No. 238. 68 pp.
- Faanes, C.A., and G.R. Lingle. 1995. Breeding birds of the Platte River Valley of Nebraska.
- Fitzner, R.E., D. Berry, L.L. Boyd, and C.A. Reick. 1977. Nesting of Ferruginous Hawks (BUTEO REGALIS) in Washington, 1974-75. Condor 79:245-249.
- Flath, Dennis L., 1982, Statewide small mammal distribution and habitat association. Mammalian Nongame Ecology Studies, NG-1.0, 1. Avian Nongame Ecology Studies, NG-2.0, 1,2,3,4. Statewide Wildlife Research. Nongame Wildlife Research & Inventory. W-120-R-13 (5853) IV.
- Friedmann, H. 1963. Host relations of the parasitic Cowbird. Museum of Natural History. Smithsonian Institution, Washington, D. C.
- Gaines, R. C. 1985. Nest site selection, habitat utilization, and breeding biology of the ferruginous hawk in central North Dakota. M.S. thesis. North Dakota State Univ., Fargo. 32 pp.
- Gilmer, D. S. and J. M. Wiehe. 1977. Nesting by ferruginous hawks and other raptors on high voltage powerline towers. Prairie Naturalist 9:1-10.
- Gilmer, D. S. and R. E. Stewart. 1983. Ferruginous hawk populations and habitat use in North Dakota. J. Wild. Mgmt. 47(1):146-157.
- Gniadek, Steve. 1983. Southwest Glendive Wildlife Baseline Inventory. BLM, Miles City District. 56pp with appendices.
- Gorman, J. D., 1984, Interagency Rocky Mountain Front Wildlife Monitoring/Evaluation Program.
- Graham, Dean, and Craig Swick., 1977, A Field evaluation of the cyclone seeder for reducing Richardson ground squirrel populations causing damage in central Montana . August 1977.
- Green, G. A. and M. L. Morrison. 1983. Nest-site characteristics of sympatric ferruginous and Swainson's hawks. Murrelet 64:20-22.
- Hall, R. S., et al. 1988. Ferruginous hawk. Pages 111-118 in Glinski et al., eds. Proc. Southwest Raptor Manage. Symp. and Workshop. Nat. Wildl. Fed. Sci. and Tech. Ser. No. 11.
- Harmata, A. R. 1981. Recoveries of ferruginous hawks banded in Colorado. North Amer. Bird Bander 6:144-147.
- Hawkins, L. 1985. Recoveries of Ferruginous hawks banded in south-central North Dakota. J. Field Ornith. 56(2):184-187.
- Hendricks, P., and K. H. Dueholm. 1995. Cliff-nesting raptor survey of the Sioux District, Custer National Forest: 1994. Unpubl. report to U.S.D.A. For. Serv., Custer N.F., Billings. 20 pp.
- Houston, C.S. 1995. Thirty-two consecutive years of reproductive success at a Ferruginous Hawk nest. Journal of Raptor Research 29:282-283.
- Howard, R.P. 1975. Breeding ecology of the Ferruginous Hawk in northern Utah and southern Idaho. M.S. thesis. Utah State University, Logan, UT. 43 pp.
- Janes, S.W. 1985. Habitat selection in raptorial birds. Pages 159-188 in M.L. Cody, editor. Habitat selection in birds. Academic Press, New York, NY.
- Jensen, J. 1995. Recovery of the ferruginous hawk. Bird Trends (Canadian Wildlife Service) 4:23-24.
- Johnsgard, P. A. 1992. Birds of the Rocky Mountains with particular reference to national parks in the northern Rocky Mountain region. Lincoln: University of Nebraska Press. xi + 504 pp.
- Kantrud, H. A. 1981. Grazing intensity effects on the breeding avifauna of North Dakota native grasslands. Can. Field-Nat. 95:404-417.
- Kantrud, H.A. and R.L. Kologiski. 1982. Effects of soils and grazing on breeding birds of uncultivated upland grasslands of the northern Great Plains. U.S.D.I., Fish and Wildl. Serv., Wildl. Res. Rep. 15. 33 pp.
- Konrad, P.M. and D.S. Gilmer. 1986. Post fledging behavior of ferruginous hawks in North Dakota. Raptor Research 20:35-39.
- Lardy, M.E. 1980. Raptor inventory and Ferruginous Hawk biology in southeastern Oregon. M.S. thesis. University of Idaho, Moscow, ID. 52 pp.
- Leary, A. W., R. Mazaika, and M. J. Bechard. 1998. Factors affecting the size of Ferruginous Hawk home ranges. Wilson Bulletin 110:198-205.
- Leary, A.W. 1996. Home ranges, core use areas, and dietary habits of ferruginous hawks in southcentral Washington. M.S. Thesis, Boise State University, Boise, ID. 72 pp.
- Lenard, S., J. Carlson, J. Ellis, C. Jones, and C. Tilly. 2003. P. D. Skaar's Montana Bird Distribution, 6th Edition. Montana Audubon: Helena, MT, 144 pp.
- Lockhart, J. Michael, 1976, Effects of coal extraction and related development on wildlife populations. Annual progress report; Calendar year 1976. In Decker Coal Company West Pit Permit. Vol. 3. 26.4.304(10-11), 305, 306, and 307. Updated Rules Rewrite, July 1, 1991. Appendix F.
- Lokemoen, J. T. and H. F. Duebbert. 1977. Ferruginous hawk nesting ecology and raptor populations in northern South Dakota. Condor 78(4):464-470.
- Lokemoen, J. T., and H. F. Duebbert. 1976. Ferruginous Hawk nesting ecology and raptor populations in northern South Dakota. Condor 78:464-470.
- MacLaren, P.A., S.H. Anderson, and D.E. Runde. 1988. Food habits and nest characteristics of breeding raptors in southwestern Wyoming. Great Basin Naturalist 48:548-553.
- Maher, W.J. 1974. Matador Project: Birds II. Avifauna of the Matador area. Canadian Committee for the International Biological Pragramme, Matador Project, Technical Report 58. University of Saskatchewan, Saskatoon, Saskatchewan. 31 pp.
- McAnnis, D.M. 1990. Home range, activity budgets, and habitat use of Ferruginous Hawks (BUTEO REGALIS) breeding in southwest Idaho. M.S. Thesis, Boise State University, Boise, ID. 81 pp.
- Meyers, H.L. 1987. Nesting Ecology of Ferruginous Hawks in Southwest Montana. Paper presented at the Montana Nongame Symposium, Feb. 11, 1987. Kalispell, MT. 14pp.
- Montana Bird Distribution Online Database. 2001. Helena, Montana, USA. April-September 2003.
- Montana Natural Heritage Program. 2003. Data derived from Element Occurences with no other known source material. BIOTICS. Helena, MT.
- Montana Prairie Dog Working Group. 2002. Conservation plan for black-tailed and white-tailed prairie dogs in Montana. Montana Fish, Wildlife and Parks. Helena MT. 51 pp.
- National Geographic Society. 1983. Field guide to the birds of North America. Second Edition. National Geographic Society, Washington, DC.
- Niemuth, N. 1992. Use of man-made structures by nesting Ferruginous Hawks in Wyoming. Prairie Naturalist 24:43.
- Olendorff, R.R. 1973. The ecology of the nesting birds of prey of northeastern Colorado. U.S. International Biological Program, Grassland Biome Technical Report 211. Colorado State University, Fort Collins, CO. 233 pp.
- Palmer, R. S., ed. 1988. Handbook of North American birds. Vol. 5. Yale Univ. Press, New Haven. 465 pp.
- Podany, M.B. 1996. Nest placement of the Ferruginous Hawk BUTEO REGALIS in northwestern Nebraska. M.A. thesis. University of Nebraska, Omaha, NE. 26 pp.
- Powers, L. R. and T. H. Craig. 1976. Status of nesting ferruginous hawks in the Little Lost River valley and vicinity, southeastern Idaho. Murrelet 57:46-47.
- Rolfe, E.S. 1896. Nesting of the Ferruginous Rough-leg. Osprey 1:8-10.
- Root, T. 1988. Atlas of Wintering North American Birds: An Analysis of Christmas Bird Count Data. The Univ. of Chicago Press, Chicago, IL. 312 pp.
- Roth, S.D., Jr., and J.M. Marzluff. 1989. Nest placement and productivity of Ferruginous Hawks in western Kansas. Transactions of the Kansas Academy of Science 92:132-148.
- Salt, W.R. and J.R. Salt. 1976. The birds of Alberta. Hurtig Publishers, Edmonton, Alberta. xv + 498 pp.
- Schmidt, R. 1981. Ferruginous Hawk breeding documented in Sargent County, North Dakota. Prairie Naturalist 13:32.
- Schmutz, J. K. 1984. Ferruginous hawk and Swainson's hawk abundance and distribution in relation to land use in southeastern Alberta. J. Wildl. Manage. 40:438-440.
- Schmutz, J. K. 1987. The effect ofagriculture on Ferruginous and Swainson's Hawks. J. Range Manage. 40:438-440.
- Schmutz, J. K. 1987a. Estimate of population size and probable causes of population stability in ferruginous hawks in southeastern Alberta. Unpubl. Rep. Univ. Saskatchewan, Saskatoon. 45 pp.
- Schmutz, J. K. and D. J. Hungle. 1989. Populations of ferruginous and Swainson's hawks increase in synchrony with ground squirrels. Can. J. Zool. 67:2596-2601.
- Schmutz, J.K. 1991. Age-related differences in reproductive success among Ferruginous and Swainson's hawks in Alberta. Journal of Raptor Research 25:160.
- Schmutz, J.K. 1991. Population dynamics of Ferruginous Hawks in Alberta. Pages 212-214 in G.L. Holroyd, G. Burns, and H.C. Smith, editors. Proceedings of the second endangered species and prairie conservation workshop. Natural History Occasional Paper 15. Provincial Museum of Alberta, Edmonton, Alberta.
- Schmutz, J.K. 1995. Updated status report on the Ferruginous Hawk (BUTEO REGALIS) in Canada. Committee on the Status of Endangered Wildlife in Canada (COSEWIC), Ottawa, Ontario. 15 pp.
- Schmutz, J.K., and S.M. Schmutz. 1980. Status of the Ferruginous Hawk. Committee on Status of Endangered Wildlife in Canada.
- Schuntz, J. K., R. W. Fyfe, D. A. Moore and A. R. Smith. 1984. Artificial nests for ferruginous and Swainson's hawks. Journal of Wildlife Management 48(3):1009-1013.
- Silloway, P. M. 1903. Birds of Fergus County, Montana. Press of the Argus, Lewistown.
- Skaar, P.D. 1969. Birds of the Bozeman latilong: a compilation of data concerning the birds which occur between 45 and 46 N. latitude and 111 and 112 W. longitude, with current lists for Idaho, Montana, Wyoming, impinging Montana counties and Yellowstone National Park. Bozeman, MT. 132 p.
- Small, A. 1994. California birds: their status and distribution. Ibis Publ. Co. Vista, California. 416 pp.
- Smith, D. G., and J. R. Murphy. 1973. Breeding ecology of raptors in the eastern Great Basin of Utah. Brigham Young University Science Bulletin, Biol. Ser. 13:1-76.
- Smith, D. G., Murphy, J. R. and N. D. Woffinden. 1983. Relationships between jackrabbit abundance and ferruginous hawk reproduction. Condor 83:52-56.
- Smith, D.G., and J.R. Murphy. 1978. Biology of the Ferruginous Hawk in central Utah. Sociobiology 3:79-98.
- Snow, C. 1974. Habitat management series for unique or endangered species: ferruginous hawk, BUTEO REGALIS. Report 13, Bureau of Land Management, U.S. Dept. of Int., Technical Note, T/N-255, Denver. 23 pp.
- Stewart, R.E. 1975. Breeding birds of North Dakota. Tri-College Center for Environmental Studies, Fargo, North Dakota. 295 pp.
- Suter, G. W., II and J. L. Joness. 1981. Criteria for Golden Eagle, Ferruginous Hawk, and Prairie Falcon nest site protection. Raptor Res. 15:12-18.
- Thomas, G. B. No Date. Personal Manuscript List of Birds in Billings Vicinity
- U.S. Forest Service. 1991. Forest and rangeland birds of the United States: Natural history and habitat use. U.S. Department of Agriculture, Forest Service Agricultural Handbook 688. 625 pages.
- Urban, Larry, 2002, Biological Resources Report: Wagner Pit Wetland Restoration Site. Proj. No. STPX 56(50) CN 4645. February 23, 2002. In Wgner Pit WS#13 Upper Yellowstone, Yellowstone County. Fin. Dist. 5 AdminDist 5.
- Western Energy Co., Colstrip, MT. Unpub., 1983, Western Energy Company's Application for Amendment to Surface Mining Permit NO. 8003, Area B: sections 7, 8, 17,18 T1N R41E, sections 12, 13 T1N R40E, Mining Expansion. March 1983.
- Western Technology and Engineering, Inc. (WESTECH)., 1994, Wildlife Monitoring Absaloka Mine Area Annual Report, 1994. Montana SMP 85005. OSMP Montana 0007D. Febr. 24, 1994.
- Weston, J.B. 1968. Nesting ecology of the Ferruginous Hawk, BUTEO REGALIS. Brigham Young University Science Bulletin 10:25-36.
- White, C. M., and T. L. Thurow. 1985. Reproduction of ferruginous hawks exposed to controlled disturbance. Condor 87:14-22.
- Wittenhagen, K. W. 1991. 1991 progress report on the ferruginous hawk in southeastern Montana. Unpubl. Rep. U.S. Bur. Land Manage., Miles City, Montana. 24 pp.
- Wittenhagen, K.W. 1992. Final report on the Ferruginous Hawk in southeastern Montana. Unpublished Report for the Bureau of Land Management; Powder River and Big Dry Resource Area, Miles City, Montana. 31 pp.
- Woffinden, N. D. 1975. Ecology of the Ferruginous hawk (BUTEO REGALIS) in central Utah: population dynamics and nest site selection. Ph.D dissertation. Brigham Young University. 102 pp.
- Woffinden, N. D. and J. R. Murphy. 1977. Population dynamics of the ferruginous hawk during a prey decline. Great Basin Naturalist 37:411-425.
- Woffinden, N. D. and J. R. Murphy. 1983. Ferruginous hawk nest site selection. J. Wildlife Management 47:216-217.
- Woffinden, N. D. and J. R. Murphy. 1989. Decline of a ferruginous hawk population: a 20-year summary. J. Wildl. Manage. 53:1127-1132.