Buteo swainsoni
(Swainson's Hawk)

Order: Falconiformes
Order Description: Vultures, Osprey, Hawks, Falcons
Family: Accipitridae
Family Description: Osprey, Hawks and Eagles

Physical Description:
19-22" (48-56 cm). Dark brown above with reddish hood, white throat and body accentuated by a dark bibClick word for definition-like band across breast. Darker gray flight feathers highlight buffyClick word for definition wing linings. Indistinctly striped tail gray above often becoming white at the base, light below with dark border. They are frequently found in dark morphs, which don't have the white breast and belly. Also, th eleading edge of the wings in both morphs is usually white, in contrast to that of Red-tails.

Similar Species- Red-tailed, Rough-legged, and Ferruginous hawks

Shrill, monotone skreeeeee, also a shorter descending scream that trails off at the end.

Breeds in portions of Alaska and western Canada, east to Minnesota and Illinois, and south to southern California, parts of Mexico, Texas, and Missouri; eastern breeding limits are unstable, Winters from southwestern U.S. and southeastern Florida (irregularly), south to South America.

Found in open pine/oak woodlands, and in cultivated land with scattered trees (e.g., alfalfa and other hay crops, and certain grain and row crops, but not vineyards, orchards, rice, or corn). During migrationClick word for definition and in winter, also found in grasslands and other open country. In Idaho, prefers to nest in trees or shrubs near riparianClick word for definition zones adjacent to agricultural lands.

Vertebrates (mainly mammals such as young ground squirrels and pocket gophers) dominate diet during breeding season; invertebrates (especially crickets and grasshoppers) are common food at other times. Depending on availability, individuals also eat snakes, lizards, birds, amphibians, and some carrion. Concentrations of Swainson's Hawks foraging on grasshoppers have been documented in Idaho.

Hunts while soaring or from perch. Builds stick nest in tree, or occasionally on cliff. nesting densityClick word for definition in suitable habitat varies from 0.1-1.6 nests/10 km2; nests average 1.4-2.4 km apart. May form pre- migratory aggregations in summer and migrate in immense flocksClick word for definition. Migrants may roostClick word for definition at night on ground in very large fields, and go without feeding during most of migration (with occasional feeding during initial and terminal stages). In Idaho, species is highly migratory (present between April and September and winters in Argentina). A 1985 survey in southern Idaho located 109 occupied nests and indicated that Swainson's Hawks were still a widespread common nester in state.

Female incubatesClick word for definition 2-3 eggs for 34-35 days/egg (laid April-May in Oregon, mainly May-June in Canada). Both adults tend young (Idaho study reported 1.17 young/nest). Young leave nest in about 30 days, fly at 42-44 days, depend on parents for 4-4.5 wk after fledging, and first breed at 2 yrs.

Element Code: ABNKC19070
Status: Protected nongame species
Global Rank: G4
State Rank: S4,NTMB
National Rank: N5B

Important State References:
Bechard, M.J., K.D. Hague-Bechard, and D.H. Porter. 1986. Historical and current distributions of Swainson's and Ferruginous Hawks in southern Idaho. Dept. Biology, Boise St. Univ., Boise. 58pp.

Photos by George Jameson, ©2002 and C. Trost, ©1999.
Design by Ean Harker©1999, 2000.
Written by Jason Karl, 2000.