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. It has been recorded as a vagrant in Northern Europe, especially Britain and Ireland. The specific epithet is from Latin varius meaning "various", "diverse" or "variegated". Linnaeus based his entry of the "small black and white bird" that had been described by the Irish physician Hans Sloane in 1725 and "Le Figuier varié de S. Domingue" that had been described by the French ornithologist Louis Vieillot in 1760. Linnaeus specified the location as Jamaica and Dominica but this was restricted to Santo Domingo in the Dominican Republic by the American Ornithologists' Union in 1910. The black-and-white warbler is now the only species placed in the genus Mniotilta that was introduced by the French ornithologist Louis Vieillot in 1816. The genus name combines the Ancient Greek μνιον/mnion meaning "seaweed" (clearly an error for μνιοεις/mnioeis meaning "moss") and τιλλω/tillō meaning "to pluck". The species is monotypic: no subspecies are recognised.
thumb|Columbus Park – Chicago
Description
The black-and-white warbler is to in length with a mass of to grams. Wingspan ranges from 7.1 to 8.7 in (18–22 cm). True to their name, black-and-white warblers are black and white in colour. Both sexes have black and white crowns with a white eyebrow, black streaking on a white belly, black wings with two white wing bars, a black tail, a black-and-white streaked back, streaky undertail coverts, and grey-black legs and feet. Breeding males have a black-and-white streaked throat and black cheek, while females have a grey cheek and a white-cream coloured throat and sides. First fall males are very similar to adult females in colour and patterning, while first fall females resemble adult females but with less streaking and a more noticeable buffy wash. Juveniles are heavily spotted, but are similar to first fall individuals otherwise. Each wing is black with two white wing bars. Female and juvenile plumages are similar, but duller and less streaky than males.
This warbler can be confused with the blackpoll warbler (Setophaga striata). The blackpoll warbler is also black and white in its summer plumage, but has a solid black cap. The black-and-white warbler can also be confused behaviourally with the pine warbler (Setophaga pinus) and yellow-throated warbler (Setophaga dominica).
Distribution and habitat
The black-and-white warbler breeds in northern and eastern North America. It ranges from the Northwest Territories to the northwest and Newfoundland and Labrador to the northeast, to North Carolina to the southeast and Texas to the southwest. This species is migratory, wintering in Florida, Central America, the West Indies and northern South America down to Peru. It occurs as a vagrant in Iceland, Ireland, Faeroes, and the UK.
thumb|Black-and-white warbler
The species occupies a broad niche, and is found in a variety of habitats. In its breeding habitat, it prefers mature forest, but will occupy successional and second growth forest. Preferred forest types include deciduous and mixed forest, and this warbler sometimes occupies swampy forest. During migration, this species prefers forest to other land cover types and is frequently found in riparian areas. In its wintering habitat, it can be found in a variety of land cover types, from mangroves to wet, dry, and cloud forest. It occupies both successional and mature forest. Males are territorial in both their summer and winter habitats.
Behaviour
Vocalization
thumb|Breeding male
The black-and-white warbler has a high-pitched song, described as a repeating that is repeated at least six times in succession. It has a chip call as well as a call that is sometimes given in flight. During migration and breeding, this warbler relies heavily on lepidopteran larvae. During migration, the black-and-white warbler sometimes joins mixed flocks to feed.
Breeding
The black-and-white warbler is of the first warblers to arrive to its spring breeding grounds. The nests are sometimes parasitized by the brown-headed cowbird (Molothrus ater). Pesticides such as fenitrothion and phosphamidon have contributed to the species' decline in the 1970s, and others such as chlorinated hydrocarbons may continue to have an effect.