Black-and-white Warbler gathering twigs for a nest in Ohio.

The Black-and-white Warbler (Mniotilta varia) is a species of New World warbler, and the only member of its genus, Mniotilta. It breeds in northern and eastern North America and winters in Florida, Central America, and the West Indies down to Peru. This species is a very rare vagrant to western Europe. [Wikipedia]

Black-and-white Warbler in Pennsylvania.

One of the earliest-arriving migrant warblers, the Black-and-white Warbler’s thin, squeaky song is one of the first signs that spring birding has sprung. This crisply striped bundle of black and white feathers creeps along tree trunks and branches like a nimble Nuthatch, probing the bark for insects with its slightly down-curved bill. Though you typically see these birds only in trees, they build their little cup-shaped nests in the leaf litter of forests across central and eastern North America. [All About Birds]

Black-and-white Warbler in Delaware.

Black-and-white Warbler Facts [All About Birds]

• The Black-and-white Warbler is the only member of the genus Mniotilta. The genus name means “moss-plucking,” a reference to its habit of probing bark and moss for insects.
• As warblers go, Black-and-white Warblers are combative: they’ll attack and fight with other species that enter their territory, including Black-capped Chickadees, Red-breasted Nuthatches, and American Redstarts. This aggressive behavior extends to the wintering grounds, where they defend territories and when feeding in mixed flocks will drive other Black-and-white Warblers away.
• Black-and-white Warblers have an extra-long hind claw and heavier legs than other wood-warblers, which help them hold onto and move around on bark.
• The oldest known Black-and-white Warbler was 11 years, 3 months old—a female that was banded in North Carolina in the 1950s and recovered in Pennsylvania more than a decade later.