junco or snowbird, small seed-eating bird of North America closely related to the sparrows. Juncos have white underparts and gray (sometimes also brown) backs. They travel in flocks. The dark-eyed junco is the most common species, comprising in E North America the subgroup sometimes called the slate-colored junco, and several Western varieties. Juncos belong to the genus Junco and are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Passeriformes, family Emberizidae.

Any of several species of finchlike birds (genus Junco, family Fringillidae), about 6 in. (15 cm) long, of Canada and the U.S. Juncos are usually a shade of gray; they have white outer tail feathers that are flashed in flight to the accompaniment of snapping or twittering calls. They are common winter birds. Their favored habitat is mixed or coniferous forest, though they are often found in fields, thickets, and city parks.

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