Swainson's Hawk

Buteo swainsoni

Order FALCONIFORMES - Family ACCIPITRIDAE - Subfamily Accipitrinae

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1. Cool Facts
2. Description
3. Similar Species
4. Sound
5. Range
6. Habitat
7. Food
8. Behavior
9. Reproduction
10. Conservation Status
11. Other Names

A common small hawk of the West, the Swainson's Hawk gathers in huge congregations to migrate more than 10,000 km to its wintering grounds in South America.

Cool Facts

• The Swainson's Hawk, declining throughout much of its range, is vulnerable to pesticide poisoning, especially on its wintering grounds. The use of pesticides in Argentina was responsible for the deaths of nearly 6,000 Swainson's Hawks in 1995 and 1996.

• Swainson's Hawk chicks frequently kill and eat the youngest nestlings. The killing of siblings may be related to food availability, but the ultimate cause is unknown.

• The Swainson's Hawk congregates in tremendous numbers during migration. Foraging and migrating flocks sometimes number into the thousands.

• Swainson's Hawk has one of the longest migrations of any American raptor - from Canada to Argentina. Only tundra breeding Peregrine Falcons travel farther. A Swainson's Hawk can make the 10,000 km trip (6214 mi) in less than two months, averaging nearly 200 km (124 mi) per day.

Description

• Size: 48-56 cm (19-22 in)
• Weight: 693-1367 g (24.46-48.26 ounces)

• Medium-sized hawk.
• Body stout.
• Wings broad.
• Rounded tail medium-long.
• Dark flight feathers contrast with pale inner wing.
• Dark chest band.
• Tail light with multiple thin dark bands, one darker and broader near tail tip.
• Face white.

• Soars with wings held slightly up in a dihedral.
• Light form with white belly and wing linings.
• Dark form all dark with white under tail and some light in wings and tail.
• Some birds intermediate between the two forms.
• When perched, wingtips barely reach tip of tail.

Sex Differences

Sexes similar in plumage, female larger.

Immature

Juvenile with similar underwing to adult. Underparts streaked with large spotting on breast.

Similar Species

• Broad-winged Hawk has similar underwing pattern, but the dark trailing edge is narrower (the tip of each feather is dark, not the entire feather), the tail bands are broader, and it lacks a dark chest.
• White-tailed Hawk has narrower dark trailing edge to wing and lacks a dark chest.

Sound

Call a high-pitched, long drawn out raspy "kreeeee."

»listen to songs of this species

Range

Summer Range

Breeds from British Columbia to southern Manitoba, southward through parts of California eastward to Minnesota and central Texas to northern Mexico.

Winter Range

Winters on South American pampas.

Habitat

Found in open country such as grassland, shrubland, and agricultural areas.

Food

During breeding season, eats mammals, birds, and reptiles. The rest of the year it eats insects, especially grasshoppers and dragonflies.

Behavior

Foraging

Locates food from exposed perches or while soaring.

Reproduction

Nest Type

A mass of sticks. Lined with leafy twigs, grass, green weeds, and wool. Placed in solitary tree in small grove.

Egg Description

Plain or sparsely marked with dark blotches around large end.

Clutch Size

Usually 1-4 eggs.

Condition at Hatching

Helpless with thick, yellowish-white down.

Conservation Status

Declining throughout much of its range. Vulnerable to pesticide poisoning, especially on its wintering grounds. The use of pesticides in Argentina was responsible for the deaths of nearly 6,000 Swainson's Hawks in 1995 and 1996.

Other Names

Buse de Swainson (French)
Aguilucho Langostero, Gavilán Longostero, Aguililla de Swainson (Spanish)

Sources used to construct this page:

England, A. S., M. C. Bechard, and C. S. Houston. 1997. Swainson's Hawk (Buteo swainsoni). In The Birds of North America, No. 265 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists' Union, Washington, D.C.