Stout bodies, broad wings and a medium-long rounded tail
Dark flight feathers contrast with pale inner wing and dark chest band
Light tail with multiple thin dark bands and one darker, broader band on the tip
Most have a white face
When perched the wingtips barley reach the tip of the tail
Sexes are silimar in plumage with females being larger
Juveniles are similar to adult form with more streaked underparts and heavy spotting on the chest
Factoids:
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
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
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