Common and hoary redpolls are 2 closely related finches of the boreal forest and Arctic tundra scrub. The common is the more widespread species of the 2, usually inhabiting subarctic forest during the summer and frequenting seed feeders in southern Canada and northern United States during the winter, when they form large flocks. Adults have characteristic red cap or “poll.” Polytypic. Length 5.3".
The common is generally a relatively small, streaked finch with a small, pointed bill; short, deeply notched tail; 2 white wing bars; black chin; red cap; and varying amounts of red underneath. Breeding male: the cap is bright red. The upperparts are brown with distinct streaking. The bright rosy red of the throat and breast extends onto the cheeks. The white flanks and undertail coverts have fine black streaking; the paler rump has distinctive streaking. Breeding female: she lacks the red breast of the male and has variable amounts of streaking underneath, usually confined to sides. Winter male: duller. Buffy wash on sides and rump. Winter female: also buffier on sides. Immature: first-year birds resemble an adult female, but they tend to be buffier. Juvenile: brown and streaked, it acquires the red cap in the late summer molt.
Two breeding subspecies in North America. The small-billed and smaller flammea has less coarse streaking and is widespread across Canada to Alaska; the large-billed and larger rostrata has coarser streaking underneath and is found on Baffin Island and Greenland. Both overlap during winter, but the clinal variation makes identification problematic.
Great care is needed to separate the common from the very similar-looking hoary. The breeding adult male hoary is a very frosty white above, and white below with a very pale pink blush on breast. Females and immatures are much more difficult; rely on the differences in bill size and shape, the presence or absence of streaking on the rump, the quality of the streaking on the flanks and undertail coverts, and to a lesser degree, location. The juvenile common can resemble a juvenile pine siskin, but it lacks yellow in the wing. The extent of interbreeding between common and hoary redpolls is unknown.
Call: when perched, gives a sweee-eet; flight call a dry rattling jid-jid-jid-jid. Song: a lengthy series of trills and twittering rattles.
Status and Distribution
Common. breeding: Found in the subarctic forests and tundra across northern Canada and much of Alaska. The rostrata breeds in tundra scrub, where it overlaps with the hoary. Winter: forms large flocks. Irruptive migrant south through much of Canada to northern United States Generally winters farther south than hoary. Vagrant: casual or accidental anywhere in southern United States.
—From the National Geographic book Complete Birds of North America, 2006