Black and white Warbler (Mniotilta varia)

24 May

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 downcurved bill. Though you typically see these birds only in trees, they build their little cup-shaped nests in the leaf litter of forests. They forage on dead limbs and bark as well as gleaning foliage at the tips of branches. Male Black-and-white Warblers arrive in early spring on their forested breeding grounds and set up territories that they defend aggressively, often singing as they chase off intruders. These defensive displays extend well past the time when such behavior has tapered off for other species.

Black-and-white Warblers eat mostly insects. Moth and butterfly larvae form the bulk of their diet during spring migration and throughout the breeding season. Other arthropod prey includes ants, flies, spiders, click and leaf beetles, wood-borers, leafhoppers, and weevils. They also feed on insects attracted to Yellow-Bellied Sapsucker sapwells.