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