Guide to North American Birds
Priority Bird
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.
This slim and graceful hawk is a common sight over grasslands of the Great Plains and the west, but only in summer: every autumn, most individuals migrate to southern South America. Although Swainson's Hawk is big enough to prey on rodents, snakes, and birds (and does so, while it is raising young), at most seasons it feeds heavily on large insects instead. Flocks are often seen sitting on the ground in fields where there are many grasshoppers or caterpillars.

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Feeding Behavior

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.


Eggs

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.


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.

Diet

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.


Nesting

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.

Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds

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Migration

Long-distance migrant, with most going to southern South America for winter. Often migrates in large flocks. May travel for several days without feeding. Mostly western, but every fall a handful of individuals show up on Atlantic Coast.

  • All Seasons - Common
  • All Seasons - Uncommon
  • Breeding - Common
  • Breeding - Uncommon
  • Winter - Common
  • Winter - Uncommon
  • Migration - Common
  • Migration - Uncommon

See a fully interactive migration map for this species on the Bird Migration Explorer.

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Songs and Calls

Long, plaintive, whistled kreee.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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How Climate Change Will Reshape the Range of the Swainson's Hawk

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.

Climate Threats Near You
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Climate threats facing the Swainson's Hawk

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.