The Tennessee warbler (Leiothlypis peregrina) is a New World warbler that breeds in eastern North America and winters in southern Central America, the Caribbean, and northern South America. The specific name peregrina is from Latin peregrinus "wanderer".
The breeding male has olive back, shoulders, rump and vent. The flight feathers are brownish-black. It has a slate gray neck, crown and eyeline. The underside is a gray-white. The female is similar to the male, but is much duller and is tinged with yellow and olive overall, especially on the underside. The Tennessee warbler has long wings, short tail and a thin, pointy bill. Juveniles and first-year birds are quite similar to the female. In winter and fall, adult male resembles juvenile and spring adult female but shows more yellow below: the grey neck and crown turn into an olive green while the underside takes a yellow hue.
Tennessee warblers resemble female black-throated blue warblers. The only difference is that the black-throated blue has a darker cheek and two white wing spots.
This bird can be confused with the red-eyed vireo, which is larger, moves more deliberately and sings almost constantly. The orange-crowned warbler can also look similar, but lacks the white eyebrow, is greyer-brown above and has yellow undertail coverts.