WatchList Species Account for Swainson’s Hawk
(Buteo swainsoni)

Qualifies for the list as a Declining Yellow List Species


Photo: USFWS
Photo: USFWS

The Swainson’s Hawk breeds in western North America, from Canada to northern Mexico and from Washington and Oregon east of the Cascades east to the Great Plains.


Favored habitat is open stands dominated by grass, sparse shrublands and small and open woodlands. It typically nests in scattered trees within this habitat. It also has adapted to foraging in some agricultural areas, particularly where the crops are wheat and alfalfa.


It winters in South America, particularly on the pampas of Argentina; the round-trip between breeding and wintering areas is as much as 12,000 miles. It is gregarious in migration and migrates in large flocks that sometimes numbering in the thousands.


During breeding the young are fed on a vertebrate diet, but unlike other raptors, during nonbreeding the Swainson’s Hawk feeds almost exclusively on insects, particularly grasshoppers in grasslands or harvested fields.


Swainson's Hawk has also declined in the western U.S. due to heavy mortality caused by use of the pesticide monocrotophos on its wintering grounds in Argentina. It is considered to be declining in Utah, Nevada and Oregon, and the California population has been reduced by as much as 90% in historical times. Numbers have also fallen significantly in the western Canadian prairie, where its main prey, Richardson’s ground squirrel, has declined.