Yellow-rumped Warbler

The Yellow-rumped Warbler is among the most numerous and widespread warblers in North America, breeding across boreal and montane conifer forests and wintering farther south than most other warblers. Its feathers show streaky gray-brown upperparts broken by small but vivid patches of bright yellow on the rump, sides, and crown, a combination that gives the species its nickname "butter-butt." Because of its abundance and tendency to winter on berries, its feathers are commonly found across a wide range of habitats.

Size and Shape

Feathers are small and narrow, typical of a warbler, with body feathers showing distinct streaking.

Color and Pattern

• Rump feathers: bright yellow, unstreaked, a hallmark of the species
• Crown and side patches: yellow, smaller and less conspicuous than the rump patch
• Back and breast feathers: gray-brown with dark streaking
• Tail feathers: dark with white patches near the tips on the outer feathers

Distinguishing from Similar Species

The bright yellow rump patch, present in all plumages, is the single most reliable feature separating this species from other streaky gray-brown warblers, most of which lack any yellow rump feathers at all.

Breeding males show the boldest pattern, with a black-streaked gray back, black breast patches, and the brightest yellow crown, rump, and side patches; females and non-breeding birds are duller and browner but retain the yellow rump. Two distinct forms occur, the eastern "Myrtle" and western "Audubon's," differing mainly in throat color (white versus yellow) rather than the rump patch. Juveniles are heavily streaked and duller before their first molt. Adults undergo a complete molt after breeding, with an additional partial molt before spring in some populations.

Yellow-rumped Warblers breed across boreal and montane coniferous and mixed forests spanning most of Canada, the northern United States, and western mountain ranges. The species winters farther north than nearly any other warbler, tolerating cold temperatures in part due to its ability to digest waxy berries, and can be found in a huge range of habitats during migration and winter, including shrubby edges, woodlands, and coastal scrub.

This warbler feeds on insects during the breeding season, often catching them in flight, and switches to berries, especially wax myrtle and bayberry, during migration and winter, which allows it to winter farther north than most warblers. It builds a cup nest in conifers, typically well concealed. Its call is a sharp, flat "check" note, and the song is a simple, warbling trill. Yellow-rumped Warblers often form large flocks in winter, moving through mixed habitats in search of fruiting shrubs.