Tennessee Warbler

The Tennessee Warbler is one of the plainer members of its family, lacking wingbars, streaking, or bold facial markings, which can make it surprisingly easy to overlook. Breeding males show a clean gray head with a bold white eyebrow stripe (supercilium), a thin dark line through the eye, and an olive-green back, with whitish underparts.

Females and fall birds are washed with more yellow-green overall, especially below, and can look considerably different from the crisp gray-and-white breeding male. The species was named after a single specimen collected near the Cumberland River in Tennessee in 1811, even though the state is only a migratory stopover for the species.

Key field marks

• Plain olive-green back with no streaking
• Gray head (breeding male) with a bold whitish supercilium and thin dark eyeline
• No wingbars, or at most one very faint bar
• Short, thin, pointed bill
• Fall birds and females are more uniformly olive-yellow, especially on the underparts

Similar species

Fall Tennessee Warblers can be confused with Orange-crowned Warbler, but Tennessee shows cleaner, unstreaked underparts, whiter undertail coverts, and a shorter tail, whereas Orange-crowned has blurry streaking below and yellow (not white) undertail coverts. Vireos can also suggest a Tennessee Warbler, but the warbler's thin bill and constant activity separate it from the more deliberate, thicker-billed vireos.

Tennessee Warblers breed across the boreal forest belt of Canada and the northern United States, favoring coniferous and mixed woodlands, bogs, and clearings, where their numbers can spike during spruce budworm outbreaks. They are among the most numerous migrants moving through the eastern and central United States each spring and fall.

In winter they range from southern Mexico through Central America into northern South America, where they are closely associated with flowering trees and shade-grown coffee plantations.

Behavior and voice

Active and often high in the canopy, Tennessee Warblers glean insects from foliage and are notable budworm predators on the breeding grounds. On the wintering grounds they readily visit flowering trees to feed on nectar and will also eat fruit, unusual habits for a warbler.

The song is loud and staccato, typically delivered in three distinct parts that increase in speed: "ticka-ticka-ticka, swit-swit-swit-swit, chew-chew-chew-chew."

Nesting

The nest is a well-hidden cup of grass, moss, and rootlets placed directly on the ground, often at the base of a shrub or hummock in a bog or open conifer stand. Clutches usually contain 4-7 eggs.