Guide to North American Birds
Conservation status The small population in Alaska is probably stable; could be affected by loss of habitat on wintering grounds.
Family Leaf-Warblers
Habitat Willow scrub. In Alaska, breeds in dense low thickets (4-10' tall) of willow, dwarf birch, or alder, mainly along streams. In Eurasia, breeds in similar habitat, but also in open forest of conifers mixed with deciduous shrubs.
Along willow-lined streams in Alaska in summer, the song of the Arctic Warbler is unmistakable: a slow trill, with an insistent or hammering sound. When the bird hops into view among the branches, it is less distinctive, plain olive and whitish with a pale eyebrow. In fall, the Arctic Warbler crosses the Bering Strait and migrates south in Asia.

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Feeding Behavior

Forages very actively among the foliage of bushes and trees, examining twigs and leaves for insects. Sometimes hovers to glean insects from foliage. Flies out to catch insects in mid-air, and may do so repeatedly when midges or mayflies are swarming.


Eggs

6-7, sometimes 5. White, finely dotted with brown. Incubation is by female only, 11-13 days. Young: Both parents feed nestlings. Young leave nest about 12-14 days after hatching. 1 brood per year.


Young

Both parents feed nestlings. Young leave nest about 12-14 days after hatching. 1 brood per year.

Diet

Mostly insects. Diet in North America is not well known. In Eurasia, feeds on a wide variety of insects, especially beetles, mosquitoes, flies, leafhoppers, caterpillars, true bugs, mayflies, sawflies, also many others. Also eats some spiders and snails.


Nesting

Nesting behavior in Alaska not well known; information here includes data from Eurasia. Male sings to defend nesting territory; in aggressive encounters between males, they may flap wings slowly while singing. Nest site is on ground, usually in mossy ground cover under dense shrubs or in crevice among roots, sometimes tucked into side of grass tussock. Typically well hidden. Nest (thought to be built by female) is a domed structure with the entrance on the side; made of grass, weeds, moss, leaves, lined with fine grass.

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

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Migration

Alaskan birds winter especially in the Philippines, also in nearby areas of southeast Asia and Indonesia. Unlike some other Alaskan breeders, this species almost never strays southward in the New World.

  • 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 over 450 bird species on the Bird Migration Explorer.

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Songs and Calls

A quick trill, introduced by zick or zick-zick-zick. The call is also zick or zirrup.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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