Guide to North American Birds
Conservation status Apparently holding steady in parts of Southwest. However, declining in the Midwest and especially in California, where it is now endangered. Habitat loss and cowbird parasitism are major threats.
Family Vireos
Habitat Willows, streamsides. Breeds in low dense growth, especially in second-growth scrub or brushy fields in Midwest, streamside thickets in Southwest, but also locally in chaparral, woodland edges, or scrub oaks. Winters in the tropics in dense low scrub, mostly near water.
When it is glimpsed in low brushy thickets of the Midwest or Southwest, this bird looks totally nondescript. When it is heard, however, it is easy to recognize, singing a jumbled clinking song, as if it had a mouthful of marbles. The species has become less common in recent years in many parts of its range, partly because it is a frequent victim of cowbird parasitism; many pairs of Bell's Vireos succeed in raising only cowbirds, not their own young.

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Feeding Behavior

Usually forages in low brush, within 12' of ground, but occasionally will feed much higher. Searches for insects among foliage, sometimes hovering while picking items from leaves or twigs; occasionally flies out to catch insects in mid-air.


Eggs

3-5, usually 4. White, usually with dots of brown or black concentrated at larger end. Incubation is by both parents (but females do more), about 14 days. Young: Both parents feed the nestlings. Young leave the nest about 11-12 days after hatching, are fed by parents for at least another 3 weeks.


Young

Both parents feed the nestlings. Young leave the nest about 11-12 days after hatching, are fed by parents for at least another 3 weeks.

Diet

Mostly insects. In breeding season, feeds almost entirely on insects, especially large ones, including caterpillars, stink bugs, wasps, bees, and weevils, also many others. Eats some spiders, and a very few berries. Winter diet unknown.


Nesting

Male defends nesting territory with incessant singing. In courtship, male may chase female; members of pair often posture and display to each other during early stages of nest building. Nest site is in low shrub or sapling, usually 2-5' above the ground and placed in a fork of a horizontal twig. Nest (built by both sexes) is a small hanging cup, its rim firmly woven into fork; made of grass, weeds, plant fibers, leaves, and strips of bark, bound with spiderwebs. Inside may be padded with feathers, plant down, moss, then lined with fine grass. Spider egg cases often added to outside.

Illustration © David Allen Sibley.
Learn more about these drawings.

Text © Kenn Kaufman, adapted from
Lives of North American Birds

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Migration

Migrates mostly at night. Arrives in Southwest in March, but does not reach northernmost nesting areas until May.

  • 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

Fast, warbled tweedle-deedle-dum? tweedle-deedle-dee! First phrase up, second phrase down.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
Learn more about this sound collection.