Black-and-white Warbler

The Black-and-white Warbler (Mniotilta varia) is a small, strikingly patterned songbird easily recognized by its bold black-and-white stripes and its peculiar, nuthatch-like foraging behavior. As the sole member of its genus, Mniotilta (which translates to 'moss-plucking'), it occupies a highly specialized ecological niche among wood-warblers, seeking its prey almost exclusively along the bark of tree trunks and major limbs rather than outer foliage.

Both sexes are covered in striking black-and-white longitudinal stripes. Key field marks include:

• Crown and Face: A prominent white stripe runs down the center of the crown, bordered by bold black stripes, with a sharp white eyebrow (supercilium). Breeding males feature a jet-black cheek patch and black throat. Females and immatures have white or pale gray cheeks and a white throat.
• Underparts: Clean white base heavily streaked with black along the flanks. Males have much darker, bolder streaking than females.
• Wings: Black wings with two prominent white wingbars.

Similar Species:

• Blackpoll Warbler (Breeding Male): Also black and white, but features a solid black cap (no white stripe down the center of the head), clean white cheeks, and does not creep along bark.
• Black-throated Gray Warbler: Easily distinguished by a tiny, bright yellow spot in front of the eye (loreal spot) and a solid black crown.

Black-and-white Warblers breed across northern and eastern North America, spanning from the Northwest Territories of Canada down to the southeastern United States. They show a clear preference for mature deciduous forests and mixed deciduous-coniferous woodlands, particularly those with damp soil or nearby water sources.

During migration, they are incredibly versatile and can be spotted in almost any wooded area, including urban parks, orchards, and backyard gardens. They are long-distance neotropical migrants, wintering in Florida, the Gulf Coast, Central America, the Caribbean, and northern South America in a wide variety of forest types.

Foraging and Behavior: Unlike most other warblers that flit actively among leaves and outer twigs, the Black-and-white Warbler acts much like a nuthatch or treecreeper. It moves deliberately vertically and horizontally along tree trunks and large branches, scanning and probing bark crevices for insects, caterpillars, beetles, and spiders. It is one of the few warblers that regularly travels downward on tree trunks headfirst.

Vocalizations:

• Song: A high-pitched, thin, squeaky series of double notes, often transcribed as weesy-weesy-weesy-weesy-weesy-weesy. It sounds remarkably like a spinning, squeaky wet wheel.
• Call: A sharp, flat chip or tsip, and a buzzy flight note during migration.

Nesting: Surprisingly for a bird that spends its foraging life high on tree trunks, the Black-and-white Warbler nests on the ground. The female builds a cup-shaped nest of leaves, bark strips, and grass, usually hidden against the base of a tree, rock, or fallen log, often thoroughly camouflaged by dead leaves.