Guide to North American Birds
Conservation status Has declined as a nesting bird in parts of the northeast during recent decades. Elsewhere, still widespread and common.
Family Wood Warblers
Habitat Mainly conifers. Breeds mostly in coniferous and mixed forests, very locally in deciduous forest. Often nests around spruce, also in white pine, hemlock, red cedar, and jack pine. An isolated race on the southern Atlantic Coast breeds in cypress swamps. During migration, occurs widely in woodland and edges. Usually winters in foothills and mountains among oaks and pines.
In the east, some of the easiest warbler voices to recognize are the patterned songs of the Black-throated Green. As if to confirm the identification, the brilliantly colored male often perches out in the open to sing, perhaps on a high twig of a spruce. He actually has two song types, used in different situations: he sings zoo zee zoo zoo zee to proclaim and defend his nesting territory, and zee zee zee zoo zee in courtship or when communicating with his mate.

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Feeding Behavior

Searches for insects among branches, twigs, and bases of leaves, moving rapidly between foraging sites. Frequently hovers to take insects from underside of leaves. Occasionally catches insects in mid-air. Males tend to forage higher than females while breeding. In late summer, often forages in mixed flocks with chickadees.


Eggs

4, sometimes 3-5. Gray to creamy white with spots or scrawls of reddish brown. Only female incubates, 12 days. In some areas, up to one-third of nests are parasitized by cowbirds. Young: Nestlings are fed only by female at first, later by male. Young leave nest 11 days after hatching. Parents split up the fledglings, each adult tending half the brood for up to 1 month.


Young

Nestlings are fed only by female at first, later by male. Young leave nest 11 days after hatching. Parents split up the fledglings, each adult tending half the brood for up to 1 month.

Diet

Insects, especially caterpillars. Feeds mainly on non-hairy caterpillars during summer, as well as beetles, true bugs, gnats, aphids, and others, also spiders. Takes poison ivy berries and other berries in migration. In winter, may eat protein corpuscles of tropical cecropia trees.


Nesting

Males establish territories by singing, also by chasing and fighting with intruding males. Nest sites are next to trunk where two or more small branches fork out of conifer, usually low (often only a few feet above ground). The race nesting in southern swamps places its nest well out from trunk, and often higher (to 50' or more above ground). Nest (built by both sexes) is open cup of twigs, grass, weeds, bark, spiderwebs, lined with plant fibers, hair, moss, and feathers.

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

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Migration

Migrates mostly at night. Fall passage may last fairly late, extending well into October, even in the North.

  • 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

Thin, buzzy, lazy zeer, zeer, zeer, zeer, zee? or faster zee-zee-zee-zoo-zee.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
Learn more about this sound collection.