Black-and-white warbler

Did You Know?

• It has been described as a flying humbug.
• Pesticides such as fenitrothion and phosphamidon contributed to its decline in the 1970s.

Taxonomy

Carl Linnaeus formally described the black-and-white warbler in 1766 under the name Motacilla varia, drawing on earlier descriptions by Hans Sloane and Louis Vieillot. The specific epithet varius means “variegated” in Latin. The species is now placed in the genus Mniotilta, introduced by Vieillot in 1816; the genus name combines Greek words for “moss” and “to pluck.” No subspecies are recognized. Hybridization with the cerulean warbler and Blackburnian warbler has been recorded, though it is not closely related to the genus Setophaga.

Description

This warbler measures 11 to 13 cm in length and weighs 8 to 15 g, with a wingspan of 18 to 22 cm. Plumage is black and white: both sexes show a black-and-white crown, white eyebrow, black streaking on a white belly, black wings with two white wing bars, a black tail, and a streaked back. Breeding males have a black-and-white streaked throat and black cheek; females have a grey cheek and white-cream throat and sides. First-fall males resemble adult females, while first-fall females are duller with a buffy wash. Juveniles are heavily spotted. The species can be confused with the blackpoll warbler, which has a solid black cap, and behaviorally with the pine warbler and yellow-throated warbler.

Distribution and habitat

The black-and-white warbler breeds from the Northwest Territories to Newfoundland and Labrador, south to North Carolina and Texas. It winters in Florida, Central America, the West Indies, and northern South America as far as Peru. The IUCN estimates its range at 11,500,000 km². In its breeding range it favors deciduous and mixed forest, including mature, successional, and swampy forest. During migration it prefers forest and riparian areas. In winter it occupies a variety of habitats, including mangroves, wet and dry forest, cloud forest, shade coffee plantations, and gardens.

Behaviour

The song is a high-pitched, repeating wee-see phrase, often given six or more times in succession. Calls include a hard tick and a soft, thin fsss. Unlike other warblers, it forages like a nuthatch, moving up and down tree trunks and along branches; it is the only North American wood-warbler to forage on bark. Its short legs and long hind toe aid this method. It also gleans insects and spiders, relying heavily on lepidopteran larvae during migration and breeding. It occasionally joins mixed flocks and has been known to eat anoles in the Caribbean. Males are territorial in both summer and winter, defending areas by singing and chasing.