Measurements
Both Sexes
- Length
- 18.9–22 in
48–56 cm - Weight
- 24.4–48.2 oz
693–1367 g
Other Names
- Buse de Swainson (French)
- Aguilucho Langostero, Gavilán Longostero, Aguililla de Swainson (Spanish)
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.
Habitat
Grassland
Found in open country such as grassland, shrubland, and agricultural areas.
Food
Mammals
During breeding season, eats mammals, birds, and reptiles. The rest of the year it eats insects, especially grasshoppers and dragonflies.
Nesting
Nesting Facts
- Egg Description
- Plain or sparsely marked with dark blotches around large end.
- Condition at Hatching
- Helpless with thick, yellowish-white down.
Nest Description
A mass of sticks. Lined with leafy twigs, grass, green weeds, and wool. Placed in solitary tree in small grove.
Nest Placement
Tree
Behavior
Soaring
Locates food from exposed perches or while soaring.
Conservation
Least Concern
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.
Credits
- 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.