Swainson's hawk (Buteo swainsoni)

Federal Register | Recovery | Critical Habitat | Conservation Plans | Petitions | Life History

Listing Status:   

General Information

Swainson's Hawks are broad-winged Buteos of between 48 and 56 cm in length with females slightly larger than males. Males and females have similar plumage. Swainson's Hawks are polymorphic with pale, light and intermediate morph plumage ranging from dark to light or rufous in color. Most Swainson's Hawks have a sharp contrast between the wing linings and flight feathers. However, some of the darkest Swainson's Hawks do not have this distinction. Swainson's Hawks are distinguishable from other Buteos by their more narrow body and wings, but are still often confused with Broad-winged, White-tailed and Short-tailed Hawks (Bechard et al. 2010).


  • Bechard, Marc J., C. Stuart Houston, Jose H. Sarasola and A. Sidney England. 2010. Swainson's Hawk (Buteo swainsoni), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/265
  • Goodrich, L.J., and J.P. Smith. 2008. Raptor migration in North America. Pp. 37-149 in K.L. Bildstein, J.P. Smith, E. Ruelas Inzunza, and R.R. Veit (eds.), State of North America's birds of prey Nuttall Ornithological Club, Cambridge, MA, and American Ornithologists' Union, Washington, D.C
  • Wheeler, B.K., C.M. White and J.M. Economidy. 2003. Raptors of Western North America: The Wheeler Guide.

  • States/US Territories in which the Swainson's hawk, Wherever found is known to or is believed to occur:  Colorado
  • US Counties in which the Swainson's hawk, Wherever found is known to or is believed to occur:  View All
  • Countries in which the the Swainson's hawk, Wherever found is known to occur:  Canada, Mexico
  • Additional species information
Current Listing Status Summary
Status Date Listed Lead Region Where Listed
Great Lakes-Big Rivers Region (Region 3) Wherever found

» Federal Register Documents

Federal Register Documents
Date Citation Page Title
1985-09-18 00:00:00.0 50 FR 37958 37967 Review of Vertebrate Wildlife; Notice of Review; 50 FR 37958-37967
2005-09-02 00:00:00.0 70 FR 52434 52436 Notice of Availability of a Draft Environmental Impact Statement/Environmental Impact Report and Receipt of an Application for an Incidental Take Permit for the East Contra Costa County Habitat Conservation Plan and Natural Community Conservation Plan, Contra Costa County, CA
2002-11-04 00:00:00.0 67 FR 67209 67210 Fish and Wildlife Service, Interior:Draft Environmental Impact Report/Environmental Impact Statement and Habitat Conservation Plan for the Natomas Basin, Sacramento County, CA; Extension of comment period and notice of availability.
1989-01-06 00:00:00.0 54 FR 554 579 ETWP; Animal Notice of Review; 54 FR 554 579
2005-03-07 00:00:00.0 70 FR 11022 11024 Preparation of an Environmental Impact Statement for Issuance of an Incidental Take Permit Associated with a Habitat Conservation Plan for Western Placer County, CA
1994-11-15 00:00:00.0 59 FR 58982 59028 ETWP; Animal Candidate Review for Listing as Endangered or Threatened Species.
1982-12-30 00:00:00.0 47 FR 58454 58460 Review of Vertebrate Wildlife for Listing as End. or Thr. Species
2013-11-04 00:00:00.0 78 FR 66058 66061 Habitat Conservation Plan for South Sacramento County, California
1991-11-21 00:00:00.0 56 FR 58804 58836 ETWP; Animal Candidate Review for Listing as Endangered or Threatened Species; 56 FR 58804 58836
2000-02-16 00:00:00.0 65 FR 7856 7856 Extension of Comment Period for the Draft Environmental Impact Statement, and Incidental Take Permit Application and Proposed Habitat Conservation Plan Submitted by Plum Creek Timberlands, L. P. for Lands in Montana, Idaho, and Washington
1995-11-17 00:00:00.0 60 FR 57722 57724 Availability of a Draft Environmental Impact Statement and Receipt of an Application for the Proposed Issuance of a Permit To Allow Incidental Take of Threatened and Endangered Species on Plum Creek Timber Company, L.P., Lands in the I90 Corridor, King and Kittitas Counties, WA

» Recovery

No recovery information is available for the Swainson's hawk.

» Critical Habitat

No critical habitat rules have been published for the Swainson's hawk.

» Conservation Plans

Habitat Conservation Plans (HCP) (learn more)
HCP Plan Summaries
Cal. Dept. of Corrections Statewide Electrified Fence Project
East Contra Costa County HCP/NCCP
Kern Water Bank
Lake Mathews
MSCP, City of Chula Vista Subarea Plan
MSCP, City of La Mesa Subarea Plan
MSCP, City of Poway Subarea Plan
MSCP, City of San Diego Subarea Plan
MSCP, County of San Diego Subarea Plan
Natomas Basin, Metro Air Park
Natomas Basin Revised HCP and Litigation Resolution - City of Sacramento, Sutter County, and Natomas Basin Conservancy
PG&E San Joaquin Valley Operations & Maintenance HCP
Plum Creek Timber Central Cascades HCP (aka I-90 HCP)
San Diego Gas & Electric
San Joaquin County Multi-Species Habitat Conservation and Open Space Plan
Western Riverside MSHCP (One permit w/ 22 permittees)

» Petitions

» Life History

Habitat Requirements

Swainson's Hawk breeding habitat includes shrub-steppe areas with scattered trees, large shrubs and riparian areas. They will often feed in agricultural areas (Goodrich and Smith 2008, p. 120). Areas they inhabit require at least small tracks of adjacent land containing lightly irrigated agricultural areas particularly with alfalfa and grass hay (their preferred habitat), or non-agricultural areas with low or moderate height vegetated areas (Wheeler 2003, p. 274). Swainson's Hawks nest in trees of a variety of species, but most often small shrubby trees in shrubb-steppe and desert habitats (Goodrich and Smith 2008, p. 120).

Food Habits

Young are fed rodents, rabbits and reptiles. However, when not breeding, adults feed almost exclusively on insects, primarily grasshoppers (Bechard et al. 2010).

Movement / Home Range

The Swainson's Hawk breeding range extends as far north as southern Alberta, Saskatchewan, Manitoba and some areas of British Columbia. In the United States, breeding occurs as far west as California, east into areas of west Minnesota and north Iowa and south into central Texas. Nonbreeding summering individuals can be found in areas of Texas, Oklahoma, Kansas, central Missouri and southern Iowa. The southern extent of the Swainson's Hawk range extends into areas of northern Mexico (Bechard et al. 2010). Swainson's Hawks are long-distance, thermal soaring migrants that travel in large flocks of thousands of individuals and may demonstrate broad front migration across the United States until their convergence point in southern Texas, eastern Mexico and the Mesoamerica corridor. Swainson's Hawks move in large flocks and prefer to utilize thermals for soaring more often than ridgeline updrafts, and are more commonly seen traveling through grassland ecosystems than along leading and diversion lines. Before fall migration in late September, Swainson's Hawks gather (in late August and early September) to feed on grasshoppers in agricultural areas to prepare for the long voyage (Goodrich and Smith 2008, p. 120).

Reproductive Strategy

Pair bonding for Swainson's Hawks begins with aerial courtship displays upon return to breeding grounds in spring around March or April. Nest building begins within the 7-15 days of arrival on breeding grounds and lasts about one or two weeks. Nests are typically built in a solitary tree or bush, or a small group or line of trees along a stream. Swainson's Hawks also favor agricultural areas including alfalfa, wheat and other row crops for building nests nearby. A small number of nests have been reported on human structures. Egg laying occurs shortly after lasting from early March until late May depending on the location. Swainson's Hawks do not typically build more than one nest per year but if a clutch or nest is destroyed they may rebuild the nest nearby. Egg incubation is approximately 28-35 days, with female staying on the nest. The female may leave the nest only briefly when the male provides her with food, which she often consumes away from the nest. In these cases the male may incubate the nest briefly. When hatched young are altricial and inactive for the first 8-10 days, but able to stand at about 13-17 days. Young can feed themselves at about 23-26 days, but the female may still feed them for up to 32 days. Juveniles first attempt to fly at 29-33 days and fly at around 38-46 days. For the first 2 weeks or so after fledging juveniles stay around 2km2 from the nest (Bechard et al. 2010).


Pesticides are a large cause of mortality for Swainson's Hawks. Large numbers of Swainson's hawks were killed on their wintering grounds in Argentina in the mid-1990's due to poisoning by a highly toxic organophosphate insecticide that has since been banned. It is unknown whether use of organophosphates in the United States affects Swainson's Hawk populations. Illegal shooting is also a threat to Swainson's Hawk populations (Wheeler 2003, p. 281).

» Other Resources

NatureServe Explorer Species Reports -- NatureServe Explorer is a source for authoritative conservation information on more than 50,000 plants, animals and ecological communtities of the U.S and Canada. NatureServe Explorer provides in-depth information on rare and endangered species, but includes common plants and animals too. NatureServe Explorer is a product of NatureServe in collaboration with the Natural Heritage Network.

ITIS Reports -- ITIS (the Integrated Taxonomic Information System) is a source for authoritative taxonomic information on plants, animals, fungi, and microbes of North America and the world.

FWS Digital Media Library -- The U.S. Fish and Wildlife Service's National Digital Library is a searchable collection of selected images, historical artifacts, audio clips, publications, and video.