Compiled by Lindsey Hernandez
Photo Credit: Rick Lewis
The Swainson’s Hawk (Buteo swainsoni) is a striking raptor that arrives in Central Texas each year from their wintering grounds in the Pampas of Argentina beginning as early as February, with most showing up between late March and mid-May. They breed primarily in the western half of Texas, especially the High and Rolling Plains, northern Edwards Plateau, and Panhandle, though breeding records stretch east toward the Red River. In Central Texas, sightings are scattered but possible anywhere with open grasslands, farm fields, or prairie-like landscapes. By late summer, as early as late July and continuing through early November, they gather in large flocks to head south again, funneling through Mexico and Central America in a spectacular migration that can span 11,000 to 17,000 miles round trip.
Adult Swainson’s Hawks show dark brown upperparts, a brown chest, a contrasting pale belly, and a bold white throat patch. When perched, their long pointed wings extend beyond their tail, and in flight they hold their wings slightly raised, similar to a Northern Harrier. Dark-phase individuals are rarer and appear chocolate brown overall. They are often seen soaring gracefully over fields, sometimes in immense swirling flocks during migration that fill the sky.
Swainson’s Hawks breed from near sea level up to about 6,000 feet in elevation, favoring open habitats like prairies, plains, deserts, and agricultural fields. They have adapted well to modern farmland, foraging over hayfields, alfalfa, pastures, and row crops, and often perch on fence posts or irrigation equipment while scanning for prey. They need scattered trees near these open areas to nest. Males select the site, usually high in a solitary tree or a small grove along a stream or field edge, though they occasionally nest in mesquite bushes, shelterbelts, or even on power poles. The nest is a bulky, rough platform of sticks, twigs, weeds, and whatever debris they find, lined with leaves, bark, or grass. Building can take up to two weeks, and pairs sometimes reuse and refurbish old nests.
Pairs are largely monogamous and often return to the same territory each year. The female lays two or three pale bluish eggs marked faintly with brown, and she does most of the 34–35 days of incubation while the male brings food and occasionally takes a turn on the eggs. Chicks hatch from March through July, fledge about 38–46 days later, and remain dependent on their parents for several more weeks before dispersing. Young Swainson’s Hawks do not breed until they are at least three years old, and pairs raise only one brood per year.
Their diet shifts dramatically with the seasons. During the breeding months in Texas and the western United States, they rely mostly on small mammals like ground squirrels, gophers, voles, mice, and rabbits, but they will also take snakes, lizards, bats, and small birds. As summer wanes and they begin their long southward journey, their diet switches almost entirely to insects—especially grasshoppers, crickets, dragonflies, and even butterflies or beetles—which they catch on the wing in acrobatic flight. This seasonal change lets them fuel their migration efficiently while traveling in enormous flocks through the Americas to their wintering grounds.
Though still considered a species of low conservation concern, Swainson’s Hawk populations have declined slowly, in part due to pesticide use on their wintering grounds. Even so, they remain one of the most awe-inspiring sights in Central Texas skies, embodying the wild sweep of migration as they move between continents each year.
Sources: Cornell Lab of Orinthology, Texas Breeding Bird Atlas and the National Audubon Society
