Swainson's Hawk

Swainson's Hawk is a slender, long-winged buteo of open grasslands and prairies across western North America, known for one of the most impressive migrations of any raptor on the continent. Most adults show a distinctive dark chest bib contrasting with a pale throat and belly, though plumage is quite variable, ranging from light to dark (rufous or melanistic) morphs.

In flight, the wings appear notably long and pointed compared to other buteos, and are often held in a shallow dihedral while soaring, giving the bird a somewhat falcon-like or Turkey Vulture-like silhouette at a distance.

Key field marks

• Long, pointed wings, held in a shallow V while soaring
• Typical adult: dark brown chest "bib" contrasting with a pale throat and belly
• Two-toned underwing in flight: pale linings, darker flight feathers
• Considerable plumage variation, including dark (rufous/melanistic) morphs

Similar species

Red-tailed Hawk has broader, more rounded wings and a streaked (not clean-cut bib) belly band pattern, plus a red adult tail. Broad-winged Hawk is much smaller and stockier with strongly banded tail. In flocks during migration, Swainson's Hawk's long, pointed wing shape and two-toned underwing pattern are key clues.

Habitat

Breeds in open grasslands, prairies, and increasingly agricultural land across the western Great Plains and Great Basin, often nesting in isolated trees or shelterbelts within otherwise treeless landscapes.

Range

Breeds across the western United States and southwestern Canada. Undertakes one of the longest migrations of any North American raptor, traveling in enormous flocks through Central America to winter on the grasslands (pampas) of Argentina, a round trip of up to 20,000 km (about 12,000 miles) each year.

Behavior

Highly social during migration, Swainson's Hawks gather in huge flocks, sometimes tens of thousands strong, funneling through Central America on their way to and from South America — one of the great raptor migration spectacles in the Western Hemisphere.

Voice

Gives a plaintive, thin, whistled "kreeeee," higher-pitched and softer than the calls of many other buteos.

Feeding and nesting

During the breeding season, hunts small mammals such as ground squirrels; outside of breeding, especially on migration and the wintering grounds, its diet shifts dramatically toward large insects, particularly grasshoppers and dragonflies, often caught by walking on the ground in freshly plowed or burned fields. Builds a stick nest in an isolated tree, often the only large tree for some distance in open prairie habitat.