The Swainson’s Hawk initially suffered from a case of mistaken identity, when a specimen collected in Canada in 1827 and illustrated by William Swainson was confused with the common buzzard (Buteo buteo) of Europe. A nephew of Emperor Napoleon eventually corrected the error: in 1832, while working in Philadelphia, French biologist Charles Lucien Bonaparte identified the hawk as a new species and named it after the original illustrator—although he based his own description on a drawing by John James Audubon.
Swainson’s Hawk feed their chicks the usual “three r’s” of the North American buteo diet: rodents, rabbits, and reptiles. But when they’re not breeding, the adults switch to a diet made up almost exclusively of insects, especially grasshoppers and dragonflies.
Groups of soaring or migrating hawks are called “kettles.” When it comes to forming kettles, Swainson’s Hawks are overachievers: they form flocks numbering in the tens of thousands, often mixing with Turkey Vultures, Broad-winged Hawks, and Mississippi Kites to create a virtual river of migrating birds. Their daytime migrations create a much-anticipated spectacle for birders who in fall and spring form their own flocks at well-known migratory points in the southern U.S., Mexico, and Central America to watch the birds stream by.
The oldest known Swainson’s Hawk was a bird first banded in 1986 in California, then recaptured and released in 2011 at 23 years, 11 months old.