Swainson's hawks nest in the canopy of tall cottonwood trees.

In 1995 three thousand Swainson's hawks were killed in Argentina after they ate insects that had been sprayed.

Early in the breeding season, Swainson's hawks hunt rodents, mainly the ground squirrels that can be abundant on arid western grasslands.

Nesting species include Swainson's hawks, great-horned owls, wood ducks, tree swallows, and black phoebe.

Swainson's hawks nest on prairies, plains and deserts west of the Mississippi River, usually from May to August.

In Oklahoma hispid cotton rats were a major prey item in the diet of Swainson's hawks (Buteo swainsoni).

Immature Swainson's hawks winter on the pampas of South America in Argentina, Uruguay, and southern Brazil.

The Refuge also provides important breeding habitat for Swainson's hawks, tri-colored blackbirds, marsh wrens, mallards, gadwall, cinnamon teal, and burrowing owls.

Some birds found around Winnipeg include ferruginous and Swainson's hawks; screech and great horned owls; as well as Canada geese and mallards.

Conger Mountain is also home to Ferruginous hawks, Swainson's hawks, mountain bluebird, red-tailed hawks, prairie falcons, kit foxes, badgers, and chukar.

They counted 4,000 dead Swainson's hawks at four sites and estimated that 20,000 of the raptors had died from aerial and ground spraying of a pesticide that forensic evidence later confirmed to be monocrotophos.

Little was known about the migration of the species until two years ago, when Mr. Woodbridge used satellite telemetry to follow two Swainson's hawks from the Butte Valley in California, north of Mount Shasta, to Argentina.

The pact commits Ciba-Geigy Ltd. of Basel, Switzerland, to remove the chemical, known as monocrotophos, from the market in the agricultural area 300 miles west of Buenos Aires where most of the world's Swainson's hawks congregate during the South American summer.