Beak of the Week – Swainson’s Hawk

Swainson’s Hawks are uncommon, but increasing breeders on the Upper Texas Coast. During fall migration, we have a great opportunity to see enormous swirling flocks, or kettles,of Swainson’s Hawks passing through. These prairie specialists have one of the longest migrations of North American raptors, with some birds flying more than 10,000 miles to their wintering grounds in Argentina. They leave their breeding grounds from August to October and arrive around two months after their journey began.

Whereas other Buteos of similar size feed on rodents and small mammals, a significant portion of the Swainson’s Hawk’s diet comes from insects, including grasshoppers, dragonflies, and crickets. However, they also catch mammals and reptiles in the summer. A common hunting strategy for these raptors is to soar above tractors in search of fleeing prey.

Swainson’s Hawks are generally found soaring in open areas like prairies, fields, and farmland, where they can easily spot their prey. Because of this, they have become an icon of the Great Plains, although their range extends from California to Texas, all the way north to Alaska. 

There are two main color morphs of Swainson’s Hawks: light and dark, although there may be considerable intermediate plumage. The more common light morph birds have a characteristic light brown bib that is easily recognizable in flight. They have faint orange barring on their flanks, a pure white throat, white underwing coverts, and a gray-brown head and back. Only 10% of Swainson’s Hawks are dark morphs, which are completely dark brown with rufous undertones. Both light and dark morphs have white undertail coverts, long and pointed wings, and a slender profile.