This handsome hawk of the American West is sometimes called “grasshopper hawk,” reflecting its favored prey.

Swainson's Hawk map, NatureServeStarting in late August, nearly the entire population of Swainson's Hawks migrates south to Argentina and Brazil in huge “kettles” or flocks. Hundreds of thousands can pass by a single site in Mexico in a single fall day. The species' migration is a round trip of more than 12,000 miles—the longest of any North American raptor.

Pesticides and Swainson's Hawk

In the 1990s, Swainson's Hawk experienced an alarming decline in population in the western United States. This decline was traced to heavy mortality on their wintering grounds. An estimated 35,000 birds had died in Argentina in one season alone, carpeting the ground with dead birds in some places.


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Swainson's Hawk_Rob McKay_SS_web

Swainson's Hawk makes a round-trip migration of more than 12,000 miles—the longest of any North American raptor. Photo by Rob McKay/Shutterstock

This disastrous die-off turned out to be due to the toxic pesticide monocrotophos, which was used to control insects in sunflower fields. The hawks were eating poisoned grasshoppers and dying in huge numbers. Although this pesticide was removed from use in the U.S. in 1991, it was still widely used in Latin America.

Saving Swainson's

In 1996, our Pesticides Programs undertook an international campaign to remove monocrotophos from the species' wintering habitat. Part of that effort was educating Argentine farmers about safer pest control techniques.

Ultimately, we successfully urged Ciba-Geigy (now Novartis), maker of the pesticide, to halt distribution of monocrotophos to Argentina. Further, the Argentine government was convinced to stop all uses—a major international conservation victory.

Since then, Swainson's Hawk numbers have stabilized.

Turbines and Hawks

Today, collisions with poorly-placed wind turbines are an increasing threat to Swainson's Hawks and other raptors such as Golden Eagles.

We continue to advocate for Bird-Safe wind energy,  calling on the federal government to establish new regulations to govern the impacts of wind energy projects on Swainson's Hawk and other migratory birds. Our report on the 10 worst-sited wind energy facilities for birds highlights the importance of siting turbines outside of migratory corridors.

Get Involved

We welcome all and every effort to help us "bring back the birds." If you would like to make a donation, please click here. Or visit our Get Involved page to learn more about how you can help. Together, we can make a difference for this special bird.


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