About the American Tree Sparrow
One of the hardiest sparrows, this is the only one likely to winter in much of the far northern United States and southern Canada, where the dark-eyed junco can also be found. At that season it is frequently mistaken for the chipping sparrow, but the 2 rarely overlap in winter. The American tree sparrow often occurs in flocks of up to 50 birds. In habitat and behavior, they are much like field sparrows, but American tree sparrows are more frequent at bird feeders. Polytypic. Length 6.3".
Gray head and nape crowned with rufous; rufous stripe behind eye; gray throat and breast, with dark central spot; rufous-buff patches on sides of breast. Back and scapulars streaked with black and rufous. Outer tail feathers thinly edged in white on outer webs. Grayish white underparts with buffy sides. Winter: more buffy; rufous color on crown sometimes forms a central stripe. Juvenile: streaked on head and underparts.
Two subspecies show weak variation in measurements and overall coloration. The small, dark nominate subspecies breeds eastward from the eastern Northwest Territories and winters eastward from the central Great Plains. The western ochracea is larger and paler, and it winters from the central Great Plains west.
See the field sparrow. The chipping sparrow rarely overlaps in range (except in certain areas in migration), has a distinct dark eye line in any plumage, and does not share the American tree sparrow’s distinctly 2-toned bill.
Call: sharp, high, bell-like tink; sometimes with a more lispy quality (poss. flight note). Flocks also give a musical teedle-eet. Song: usually begins with several clear notes followed by a variable, rapid warble.
Status and Distribution
Fairly common. Uncommon to rare west of Rockies. Breeding: breeds along edge of tundra, in open areas with scattered trees, brush. Winter: weedy fields, marshes, groves of small trees. Migration: one of the late-fall and early-spring migrants. Fall migration in United States typically mid- or late October–late November; spring migrants depart mid-March–early April; accidental in United States after early May (mid-April in midlatitudes). Vagrant: casual to southern California, central Texas, and the Gulf Coast.
Possible declines in wintering population in East.
—From the National Geographic book Complete Birds of North America, 2006