Black-and-white warblers are small songbirds that breed in northern and eastern parts of North America. True to their name, these birds are black and white in color. 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 colored throat and sides. Summer male black-and-white warblers are boldly streaked in black and white and have been described as flying humbugs. Each wing is black with two white wing bars. Female and juvenile plumages are similar but duller and less streaky than males.
Black-and-white warblers breed in northern and eastern North America. Their range extends 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. These are migratory birds that winter in Florida, Central America, and northern South America down to Peru. Black-and-white warblers are found in a variety of habitats. In their breeding habitat, these birds prefer deciduous and mixed forest and sometimes occupy the swampy forest. During migration, they are frequently found in riparian areas. In their wintering habitat, Black-and-white warblers can be found in a variety of land cover types, from mangroves to wet, dry, and cloud forest. They may also winter in shade coffee plantations and gardens.
Black-and-white warblers are generally solitary and prefer to spend time singly, however, during migration, they sometimes join mixed flocks to feed. These diurnal birds forage like a nuthatch, moving up and down tree trunks and along branches. They forage on tree trunks and limbs to feed on insects below the bark's surface. Their short legs and long hind toe are adaptations to this foraging method and they are unique among warblers in their time spent foraging on tree trunks and inner branches. They also glean for insects. Black-and-white warblers have a high-pitched song, described as a repeating 'wee-see' that is repeated at least 6 times in succession. They have a 'chip' call and a 'seet-seet' call that is sometimes given in flight.
Black-and-white warblers are carnivores (insectivores). Their diet consists of insects and other arthropods, including lepidopteran larvae, beetles, ants, and spiders. During migration and breeding, these small birds rely heavily on lepidopteran larvae.
Black-and-white warblers are monogamous and form pairs. They produce one brood per year. In the southernmost range of their breeding habitat, these birds can begin breeding mid-April. Males are territorial and defend their territory, both by singing and chasing competitors away. When a female arrives in a male's territory, he pursues her in an effort to breed. The male may also display by flapping his wings. Black-and-white warblers prefer to nest in wetter areas. They construct a cup-shaped nest, often located on the ground among roots or against a tree, or in crevices on tree stumps. The nest is made with grassy material, bark, and dry leaves, and lined with softer material such as moss and hair. The female is responsible for most of the nest-building. She lays 4-5 light brown and speckled with darker brown eggs and incubates them alone for 10-12 days. During incubation, the female is sometimes fed by the male. Both parents care for the nestlings which are born helpless. The chicks fledge after 8 to 12 days and stay around the nest around 2-3 weeks more while they improve their flight ability. During this time, the parents remain nearby.
The main threats to Black-and-white warblers include habitat loss and degradation, especially forest fragmentation. If habitat loss continues, in either or both summer or wintering habitat, these birds may continue to decline in the future. They also suffer from the use of pesticides and collisions with tall buildings and radio towers during their night migrations.
According to the All About Birds resource the total breeding population size of the Black-and-white warbler is 20,000,000 birds. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.