Aurora's Swainson's Hawks about to migrate south...

Photo by BarrytheBirder

The many Swainson's Hawks that have been making south-west Aurora, Ontario, their home this year, are about to leave our town and head south for the winter.   It will be an astonishing journey as they travel 12,000 miles round-trip between their grassland breeding grounds in western and central North America and their wintering territories in the pampas plains of southern Argentina.

During fall migration these hawks form huge flocks with other migratory raptors, sometimes numbering in the tens of thousands, in a 'River of Raptors' that flows from southern Mexico to Panama and beyond to southern Argentina.

Related to Red-tailed Hawks, Swainson's Hawks are more slender (about the size of a Mallard Duck) and have long, pointed wings that span nearly four feet.

Though they hunt mostly small mammals in the summer, Swainson's Hawks feast mostly on grasshoppers and locusts while in South America.   In Argentina, Swainson's are nicknamed "grasshopper hawks".

These beautiful birds have hunted bug for millennia, but modern agricultural control practices were putting them at risk, with pesticides in Argentina killing over 20,000 Swainson's Hawks in just two years in 1990s.

The tragedy propelled scientists from the U.S. and Argentina to ban the deadly pesticides, preventing more deaths and allowing birds populations to recover.   Today, more than 800,000 Swainson's Hawks are soaring across the U.S. and Canada as living proof of beneficial human intervention.

Please comment if you wish.

BarrytheBirder