Swainson's Hawk - Buteo swainsoni
State Rank Reason (see State Rank above)
While there is concern about the status of some local populations, statewide populations have increased in recent years.
- Details on Status Ranking and Review
ScoreU - Unknown
ScoreG - 200,000-2,500,000 km squared (about 80,000-1,000,000 square miles)
Comment380,531 square kilometers based on Natural Heritage Program range maps that appear on the Montana Field Guide
ScoreD - Moderate Decline (decline of 25-50%)
CommentSpecies was heavily persecuted by early settlers who considered it a threat to domestic foul and sheep. Pesticide application in both breeding and wintering range has also been identified as a cause for declines in last half century.
ScoreF - Increasing. Increase of >10% in population, range, area occupied, and/or number or condition of occurrences
CommentBreeding Bird Survey (BBS) data is of moderate credibility in Montana and shows a significant increase of 2.4% per year or + 27% increase per decade. BBS for surrounding states and provinces mostly show increasing trends. Raptor survey route data in Montana for the past 35 years shows mostly stable, but sometimes widely varying, numbers. Over the last 10 years, raptor survey route data shows a steady and increasing trend.
ScoreF - Widespread, low-severity threat. Threat is of low severity but affects (or would affect) most or a significant portion of the population or area.
CommentHabitat loss, pesticides on summer and winter ranges and vehicle collisions are probably the greatest threats.
SeverityLow - Low but nontrivial reduction of species population or reversible degradation or reduction of habitat in area affected, with recovery expected in 10-50 years.
CommentProbably respond relatively quickly to habitat and prey base changes.
ScopeModerate - 20-60% of total population or area affected
CommentGrassland/shrubland habitats being widely (20-605) affected.
ImmediacyModerate - Threat is likely to be operational within 2-5 years.
ScoreB - Moderately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance over a period of several years (on the order of 5-20 years or 2-5 generations); or species has moderate dispersal capability such that extirpated populations generally become reestablished through natural recolonization (unaided by humans).
CommentModerately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance within 5-20 years or 2-5 generations. Species has good dispersal capabilities such that extirpated populations generally become reestablished through natural recolonization.
ScoreC - Moderate. Generalist. Broad-scale or diverse (general) habitat(s) or other abiotic and/or biotic factors are used or required by the species but some key requirements are scarce in the generalized range of the species within the area of interest.
CommentModerate Generalist. Forage over a large variety of habitats and nest sites are not a limiting factor.
Raw Conservation Status Score
3.5 + 0.0 (geographic distribution) + 0.0 (environmental specificity) + 0.25 (short-term trend) + 0.0 (threats) = 3.75
Adults are dark brown above, and white with chestnut-brown bib below; tail grayish-brown, finely barred, becoming lighter toward the base. In flight, the wing undersides appear two-toned, with the flight feathers dark and the leading edge of the wing white. The wings of Swainson's Hawks are slightly more pointed than those of other buteos. Dark-phase Swainson's Hawks appear all dark brown above and below and on the entire wing undersides, making them look like a miniature eagle. Intermediate color phases occur, with dark brown bibs and chestnut barring on the belly. Immatures lack the bib and are more strongly barred or streaked underneath. Swainson's Hawks range in length from 18 to 22 inches, and have a wingspan of 48 to 52 inches.
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.
All other buteo hawks have white flight feathers. Also, Swainson's Hawks have longer, narrower wings than other buteos. Red-tailed Hawks are slightly larger, have a dark belly band and no bib, while Swainson's Hawks have a bib, but no belly band.
Western Hemisphere Range
eBird Occurrence Map
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Observations in Montana Natural Heritage Program Database
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")
(Observations spanning multiple months or years are excluded from time charts)
Swainson's Hawks leave in late September, migrating to Argentina for the winter. They often migrate in large flocks. Bozeman migration: April 25 to May 15 and September 2 to Septmeber 10; no detectable peaks (west of main migration path). Migration late April and early September (Davis 1961).
Swainson's Hawks nest in river bottom forests, brushy coulees, and shelterbelts. They hunt in grasslands and agricultural land, especially along river bottoms. In Bozeman area, the birds inhabit the drier, open parts of the Gallatin valley (Skaar 1969).
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 (common or occasional) 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 2012, 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 observation 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 listed as associated with 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 listed as 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.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific 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 assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
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: mtnhp.org/requests
) 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. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- 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
Human Land Use
Recently Disturbed or Modified
Shrubland, Steppe and Savanna Systems
Wetland and Riparian Systems
- Occasionally Associated with these Ecological Systems
Forest and Woodland Systems
Shrubland, Steppe and Savanna Systems
Swainson's Hawks prey on a wide variety of small mammals, songbirds and insects.
Formerly rare in the Fortine area, but not seen in summer for 30 years. Has apparently decreased in numbers in the Bozeman area in the last century (Skaar 1969).
Flimsy nests are built in trees and shrubs, often as low as four feet from the ground. Swainson's Hawks are more tolerant of humans than other hawks, and will often nest close to occupied houses. One to three eggs are laid in May, and incubated for about 28 days. The young fledge in late July and August. Nests with eggs range from early May to mid-July, but June is the common nesting month (Davis 1961).
- Literature Cited AboveLegend: View Online Publication
- Davis, C.V. 1961. A distributional study of the birds of Montana. Ph.D. dissertation. Oregon State University, Corvallis. 462 pp.
- Marks, J.S., P. Hendricks, and D. Casey. 2016. Birds of Montana. Arrington, VA. Buteo Books. 659 pages.
- 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.
- Additional ReferencesLegend: View Online Publication
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- Bird Conservancy of the Rockies. 2017. Pocket Guide to Northern Prairie Birds. Brighton, CO: Bird Conservancy of the Rockies. 98 p.
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- Cameron, E. S. 1891. In regard to migration of Swainson Hawks in Montana. Ibis 33(4):623-625.
- Cameron, E. S. 1908. Changes of plumage in Buteo swainsoni. Auk 25:468-471.
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- 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.
- Dood, A.R. 1980. Terry Badlands nongame survey and inventory final report. Montana Department of Fish, Wildlife, and Parks and Bureau of Land Management, Helena, MT. 70 pp.
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- Dubois, K. 1988. Kevin Rim/Sweetgrass Hills raptor survey. Bureau of Land Management. 8 pp. plus data appendices.
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- ECON, Inc. (Ecological Consulting Service), Helena, MT., 1976, Colstrip 10 x 20 Area wildlife and wildlife habitat annual monitoring report, 1976. Proj. 135-85-A. December 31, 1976.
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- Gillihan, SW. and T. VerCauteren. 2015. Pocket Guide to Prairie Birds. Brighton, CO: Bird Conservancy of the Rockies. 91 p.
- Gilmer, D. S., and R. E. Stewart. 1984. Swainson's hawk nesting ecology in North Dakota. Condor 86:12-18.
- Gniadek, S. 1983. Southwest Glendive Wildlife Baseline Inventory. Miles City, Mont: Bureau of Land Management, Miles City District Office. 56 pp with appendices.
- Goodell, J. 2012. Morse Land Company Breeding Bird Inventory And Analysis. High Desert Museum. Bend, OR. 42 pp + Appendices.
- 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.
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- Hansen, R. W. 1995. Ecological relationships between nesting Swainson's and red-tailed hawks in southeastern Idaho. J. Raptor Res. 29:166-171.
- Hendricks, P, S. Lenard, and C. Currier. 2011. Grassland Bird Surveys in North Valley County and Northwest Phillips County, Montana: 2011 Summary. Report to the USDI Bureau of Land Management. Montana Natural Heritage Program. Helena, MT. 7pp.
- Hendricks, P. and M. Roedel. 2001. A faunal survey of the Centennial Valley Sandhills, Beaverhead County, Montana. Report to the U.S. Bureau of Land Management and U.S. Fish and Wildlife Service. Montana Natural Heritage Program, Helena, MT. 44 pp.
- 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.
- Hendricks, P., S. Lenard, C. Currier, and J. Carlson. 2007. Grassland bird surveys in north Valley County, Montana: 2001-2006. Report to the Bureau of Land Management, Glasgow Field Office. Montana Natural Heritage Program, Helena, Montana. 19 pp. plus appendices.
- Hendricks, P., S. Lenard, D.M. Stagliano, and B.A. Maxell. 2013. Baseline nongame wildlife surveys on the Fort Peck Indian Reservation. Report to the Assiniboine and Sioux Tribes of the Fort Peck Indian Reservation. Montana Natural Heritage Program, Helena, MT. 83 p.
- Hoffmann, R. S. 1960. Summer birds of the Little Belt Mountains, Montana. Occasional Papers of Montana State University No. 1, Missoula.
- 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.
- Kevin Rim Raptor Study Group. 1991. Impacts of oil and gas development on raptors associated with Kevin Rim, Montana. Unpublished report for the Bureau of Land Management, Great Falls. 37pp.
- Land & Water Consulting, Inc., Missoula, MT., 2002, Montana Dept. of Transportation Wetland Mitigation Monitoring Report, Year 2001: Beaverhead Gateway, Dillon, Montana. Proj. No. 130091.011. July 2002. In 2001 Wetland Mitigation Monitoring Reports, Vol. I.
- Lenard, S. 2006. Birds of Blaine County, Riparian Point Count Surveys 2005. Report to the Bureau of LandManagement, Havre Field Station, Havre, Montana. Montana Natural Heritage Program, Helena, MT. 16pp.plus appendices.
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