Which hawk migrates from North America to the grasslands of South America each year?

The Swainson’s hawk migrates from North America to the grasslands of South America each year.

It breeds across western Canada, the western United States, and parts of northern Mexico. In autumn, most birds travel south through Central America before reaching Argentina and surrounding regions, where they spend the non-breeding season on open agricultural and grassland landscapes.

This migration can cover roughly 10,000 km. The hawks often gather in large kettles, circling on rising warm air to gain altitude and conserve energy. Such concentrations are especially visible at mountain passes and other geographic bottlenecks.

Swainson’s hawks are sometimes mistaken for red-tailed hawks, but their slimmer shape and characteristic migration distinguish them. A major historical conservation problem arose in Argentina when pesticide-treated grasshoppers poisoned wintering birds during the 1990s.