Guide to North American Birds
Conservation status Apparently far more common today than in early 19th century, with much greater area of second growth brush in East. Numbers may have declined somewhat in recent decades.
Family Wood Warblers
Habitat Slashings, bushy pastures. Habitat specialist, expanding range since 19th century as forests were cut over in the eastern United States. Breeds in second-growth deciduous woods, overgrown fields, and edge habitat. Prefers brushy thickets, briers, and brambles. Winters in tropics in forest edge and second growth.
In leafy second-growth woods, clearings, and thickets, this warbler is often common, hopping about in the saplings with its tail cocked up at a jaunty angle. It is apparently much more numerous today than it was historically: John James Audubon, roaming eastern North America in the early 1800s, saw this bird only once. The cutting of forests evidently has created more brushy habitat for Chestnut-sided Warblers, even as it has made other birds less common.

Photo Gallery

Feeding Behavior

Forages by hopping actively among branches of shrubs and small trees, searching for insects among leaves and twigs, hovering momentarily to take items from foliage. Typically takes insects from undersides of leaves. Also darts out to catch flying insects in mid-air.


Eggs

Usually 4, sometimes 3-5. Whitish with brown markings. Incubated 11-12 days by female. Cowbirds frequently lay eggs in nests of this species. Young: Both parents feed the nestlings. Young leave the nest about 10-12 days after hatching.


Young

Both parents feed the nestlings. Young leave the nest about 10-12 days after hatching.

Diet

Mostly insects. During nesting season, known to eat caterpillars, flies, small moths, small grasshoppers, beetles, spiders; also a few berries. May eat slightly more berries in winter in the tropics, but insects still make up over 90% of diet then.


Nesting

Male sings to defend nesting territory. During courtship, male displays to the female by fluffing his plumage, raising his yellow crown feathers, spreading and vibrating his wings and tail. Nest: Placed in low dense shrubs or tangles, such as blackberry or rhododendron, or in deciduous saplings, such as alder or maple. Loosely constructed open cup nest (built by the female) is made of cedar or grapevine bark strips, fibrous weeds, grasses, roots, and fine plant down, lined with fine grass and animal hair. Nest may be attached to twigs with spiderwebs.

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

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Migration

Mostly migrates at night. Peak migration in most areas is during May and September. Strays appear regularly in West, especially in fall.

  • 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

Rich and musical with an emphatic ending, sometimes interpreted as very very pleased to meet cha!
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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How Climate Change Will Reshape the Range of the Chestnut-sided Warbler

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 Chestnut-sided Warbler

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.