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The 'Grasshopper' Hawk's High-Stakes Migration
On their wintering grounds in South America, Swainson's Hawks feast on insects.
© Nick Athanas
Swainson’s Hawks make an incredible journey every year, migrating 12,000 miles round-trip from North America’s prairies to Argentina’s pampas. What makes them truly unique is their diet. Most hawks hunt rodents and reptiles, but Swainson’s Hawks switch to insects, feasting on grasshoppers and locusts in South America. In the 1990s, this diet nearly led to disaster when pesticides in Argentina killed over 20,000 hawks in two years. But a successful international conservation effort saved them.
BirdNote®
Swainson’s Hawk: The Grasshopper Hawk’s High-Stakes Migration
Written by Lucina Melesio
This is BirdNote.
[Swainson’s Hawk flight calls]
It’s late summer in Canada, and this Swainson’s Hawk is about to embark on an astonishing journey. Every year, they travel 12,000 miles round-trip between their grassland breeding grounds in western North America and their wintering territories in the pampas plains of Argentina. During fall migration, Swainson’s Hawks form massive flocks with other migratory raptors, sometimes numbering in the tens of thousands, creating a “River of Raptors” that flows from southern Mexico to Panama and beyond.
[Swainson’s Hawk calls]
Swainson’s Hawks are related to Red-tailed Hawks, but they are more slender —about the size of a mallard duck— and have long, pointed wings that span nearly four feet.
[Swainson’s Hawk calls and bugs]
Though they mostly hunt small mammals in the summer, Swainson’s Hawks feast almost exclusively on insects like grasshoppers and locusts while in South America. That’s actually what gives them their name in Argentina: Aguilucho Langostero or “grasshopper hawks.”
These beautiful birds have hunted bugs for millennia, but recent agricultural practices have put them both at risk. In the 1990s, pesticides in Argentina killed over 20,000 Swainson’s Hawks in just two years.
[Swainson’s Hawk calls]
The tragedy propelled scientists from the U.S. and Argentina to join forces. They banned the pesticide, preventing more deaths and gradually allowing bird populations to recover. The more than 800,000 Swainson’s Hawks now soaring across the Americas are living proof that when we choose to act, we can make a difference.
For BirdNote, I’m Sheky Espejo.
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Senior Producer: Mark Bramhill
Producer: Sam Johnson
Producer: Kizaya Studios
Managing Editor: Jazzi Johnson
Managing Producer: Ariana Remmel
Content Director: Jonese Franklin
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Swainson's Hawk ML112977571 recorded by Julia Moning. Swainson's Hawk ML4313 recorded by Randolph Little.
BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.
© 2025 BirdNote October 2025
Narrator: Sheky Espejo
ID# SWHA-02-2025-10-14 SWHA-02
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