Adults (intermediate morph). Photo: Becky Matsubara/Flickr (CC BY 2.0)
Buteo swainsoni
| Conservation status | Has declined seriously in much of its nesting range, especially in California. Causes of decline not well understood. |
|---|---|
| Family | Hawks and Eagles |
| Habitat | Plains, dry grassland, farmland, ranch country. Breeds most commonly on northern Great Plains, in prairie regions with scattered groves of trees for nest sites. Less common in dry grassland farther west and in heavily farmed country. In migration, often pauses in fields where insect larvae may have been turned up by the plow. |
May hunt by soaring over grassland, or by perching and scanning the ground. Skilled at catching flying insects in the air. When feeding on insects in fields, may catch them by running about on ground. May concentrate near grass fires, watching for prey driven into the open by the flames.
2-3, sometimes 1 or 4. Pale bluish white fading to dull white, usually lightly spotted with brown. Incubation is almost all by the female, about 34-35 days. Male brings food to female during incubation period. Young: Both parents bring food for young, but at first female may remain with young much of time while male hunts. Young can fly about 42-44 days after hatching; may remain with parents until fall migration.
Both parents bring food for young, but at first female may remain with young much of time while male hunts. Young can fly about 42-44 days after hatching; may remain with parents until fall migration.
Mostly small mammals and reptiles in early summer, large insects at other seasons. When feeding young, preys on ground squirrels, pocket gophers, mice, snakes, lizards, small birds; sometimes bats or carrion. At other seasons, diet shifts to mostly large insects. May feed heavily on grasshoppers and caterpillars in late summer. In winter in Argentina, follows and feeds on swarms of nomadic dragonflies.
In courtship, members of pair engage in display flights, with circling and steep dives. On prairies with scattered groves of trees, may have conflicts with Great Horned Owl where both species attempt to nest in same grove. Nest site is usually in a tree or large shrub in open country, usually 15-30' above ground, but may be lower or higher; generally well hidden within foliage. May be built on top of old magpie nest. Sometimes nests on ledge of cliff or steep slope. Nest is a platform of sticks, lined with finer twigs, weeds. Often adds leafy green branches to nest.
Audubon’s scientists have used 140 million bird observations and sophisticated climate models to project how climate change will affect this bird’s range in the future.
Zoom in to see how this species’s current range will shift, expand, and contract under increased global temperatures.
Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.
Audubon outreach biologists Mikko Jimenez and Chad Witko discuss this ambitious project to protect birds along their full migratory journeys.
Location: 564 W. 149th St., New York, NY 10031
Swainson's Hawks star in the latest episode of National Geographic's nature-doc series, Hostile Planet.
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