Mniotilta varia primarily eats insects that are gleaned from trunks and limbs of trees in a very similar manner to nuthatches. Its main food items include caterpillars, flies, bugs, beetles, borers, spiders, larvae, and egg masses. It is the only North American wood-warbler that regularly forages on bark.
Mniotilta varia creeps along branches and trunks from the canopy to the ground, picking and probing with its thin bill. It often creeps upside-down along the undersides of branches, and may creep downward headfirst. By foraging from bark in this manner, M. varia can glean enough food (including dormant insect forms) before trees leaf out to allow it to arrive at its breeding grounds earlier than other warblers. Though it specializes in bark gleaning, Mniotilta varia also makes use of other foraging behaviors more typical of warblers, including occasional flycatching and foliage gleaning.
Animal Foods: insects; terrestrial non-insect arthropods
Primary Diet: carnivore (Insectivore )
Little information is available about predation of Mniotilta varia. As a ground nesting species, M. tilta is probably vulnerable to predation by a wide variety of predators, particularly during the breeding season. Probable nest predators include common forest bird and mammal species such as blue jays, deer mice, eastern chipmunks, northern flying squirrels, red squirrels, raccoons and black bears.
Mniotilta varia is entirely black and white in all plumages, except for a creamy wash on the face and flanks of many females. The head has a white median crown stripe bordered by black. A bold white border to the tertials is distinctive, as are the black uppertail coverts with white fringes. The black-and-white striped crown and back are distinctive in all plumages. Mniotilta varia averages 11 to 13 cm long, although females are generally smaller than males. It has a mass of 9 to 15 g. Mniotilta varia has an elongated hind claw, shortened tarsi, and a long thin bill with a slightly curved culmen. These modifications allow M. varia to forage on tree trunks and branches in a manner similar to nuthatches.
Range mass: 9 to 15 g.
Range length: 11 to 13 cm.
Sexual Dimorphism: male larger
Other Physical Features: endothermic ; bilateral symmetry
Average basal metabolic rate: 0.12727 W.
The oldest known black-and-white warbler lived at least 11 years. One study estimated annual adult survivorship to be 71%.
Range lifespan
Status: wild: 11 (high) years.
Average lifespan
Status: wild: 135 months.
Mniotilta varia breeds in mature and second-growth deciduous and deciduous-conifer forests, favoring deciduous habitats. Large trees are a critical component of the habitat M. varia prefers. There are generally understory and ground-cover plants, tangles, and dead leaves for nest concealment. Mniotilta varia winters in a variety of forests from high-elevation cloud forests to lowland evergreen and deciduous forests, woodland borders, gardens, and coffee plantations.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: forest ; rainforest
Mniotilta varia breeds throughout the eastern United States and much of Canada. Boreal areas through central and eastern Canada, from northeastern British Columbia east to Newfoundland and Labrador, make up its northern range. In the United States, Mniotilta varia breeds along the east coast from Maine, through New York, south to North Carolina and western South Carolina, and west to parts of Alabama and Mississippi. Mniotilta varia does not breed in the Mississippi River valley, but does breed as far west as eastern Texas and Oklahoma. In the midwest, M. varia breeds in northern portions of Michigan, Wisconsin, and Minnesota. This warbler winters from southern Florida through the Bahamas, Mexico, Central America, and the Caribbean to northern South America.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Mniotilta varia affects the populations of insects it eats. It also provides food for its predators. Finally, M. tilta hosts external and internal parasites, including feather mites, lice and blood parasites.
We do not know of any way that Mniotilta varia affects humans.
There are no known negative effects of Mniotilta varia on humans.
Mniotilta varia is very sensitive to fragmentation of forested breeding habitat. Populations of Mniotilta varia have been increasing as forests have regenerated after massive 19th century deforestation. The worldwide population of Mniotilta varia is estimated at about 14,000,000 individuals. Regional declines have occurred where forest fragmentation is again occurring. These declines may be compounded by cowbird parasitism, of which M. varia is a frequent host. There is also evidence that pesticide use has had a negative effect on M. varia populations.
Mniotilta varia is not threatened or endangered. It is, however, protected under the U.S. Migratory Bird Act.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Mniotilta varia communicates via vocalizations and physical displays. The song of M. varia is a lengthy (up to 3 seconds) series of thin, squeaky, very high-pitched notes (said to sound like wee-see) in a series of 6 to 10 phrases. It is distinguished from other high-pitched warbler songs by the chanting rhythm and the absence of a complex ending. A second longer, more varied, but less common song is sometimes given in flight. Calls include a dull chip or tik, as well as a doubled seet-seet (sometimes singe) flight call.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
The scientific name Mniotilta varia derives from the unique bark-foraging behavior (Mniotilta refers to "moss-plucking") and the unique plumage evident in all seasons (varia refers to "variegated"). No subspecies are presently recognized.
Mniotilta varia is most likely monogamous.
Mating System: monogamous
Mniotilta varia is one of the first warblers to arrive in the spring. There is some evidence that it will return to the same territories in successive years. Preferred breeding habitat includes deciduous and deciduous-conifer forests, especially on hillsides, in ravines and swampy forests.
Mniotilta varia typically breeds between April and August. Males arrive first in the spring. Soon after arriving, they set up territories and begin courting a mate. The courting male pursues the female intermittently over a long period of time, with much song and display of plumage. After pursuing the female, the male will perch near the female with fluttering wings.
The female is the principal nest builder. The nest is a cup, generally on the ground at the base of a tree or fallen log and concealed under dead leaves or branches. The nest is made of leaves, coarse grass, and other fine materials used for lining.
The female lays 4 to 6 (usually 5) white eggs that are flecked with brown and 16 to 18 mm long. Incubation, completed by the female only, takes 10 to 12 days. The male sometimes feeds the incubating female. Both parents feed the young and defend the nest. The young leave the nest 8 to 12 days after hatching. They remain in the parents' territory for 2 to 3 weeks after fledging. Generally there is only one brood per year, although two broods per year is possible.
Breeding interval: Most black-and-white warblers raise one brood per summer. Some pairs are able to raise two broods.
Breeding season: Black-and-white warblers breed between April and August.
Range eggs per season: 4 to 6.
Range time to hatching: 10 to 12 days.
Range fledging age: 8 to 12 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Average eggs per season: 5.
Mniotilta varia breeding pairs share parental responsibilities. The female builds the nest and incubates the eggs. Both parents feed the young and defend the nest.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth; pre-weaning/fledging
A medium-sized (4 ½ - 5 ½ inches) wood warbler, the Black-and-white Warbler is most easily identified by its black-and-white striped body, streaked flanks, and thin black bill. Males have black and white stripes on the crown and throat, whereas the female is only striped on the crown and is paler on the throat and below. Both sexes have dark tails, dark legs, and conspicuous black- and-white wing bars. The Black-and-white Warbler breeds across much of the eastern United States and southern Canada, absent only from parts of the southeast and Midwest. In winter, this species may be found along the coast of the southeastern U.S. from North Carolina to Florida, and along the coast of Texas. South of the U.S., this species is a winter visitor to central and southern Mexico, Central America, the West Indies, and parts of northern South America. Black-and-white Warblers breed in a variety of deciduous or mixed deciduous and evergreen forest habitats, with a preference for mature forests. In winter, this species occurs in numerous kinds of habitats ranging from scrubland to moist tropical forests. Black-and-white Warblers eat small invertebrates, primarily insects (including caterpillars) and spiders. Unusually for a wood warbler, the Black-and-white Warbler feeds by picking prey out of crevices in bark while climbing up the sides of tree trunks and large branches. As this interesting behavior recalls that of a nuthatch or creeper, birdwatchers who believe they’ve caught a momentary glimpse of either may want to consider taking a closer look: they may well have seen a Black-and-white Warbler instead. This species is primarily active during the day, but, like many migratory songbirds, this species migrates at night.
A medium-sized (4 ½ - 5 ½ inches) wood warbler, the Black-and-white Warbler is most easily identified by its black-and-white striped body, streaked flanks, and thin black bill. Males have black and white stripes on the crown and throat, whereas the female is only striped on the crown and is paler on the throat and below. Both sexes have dark tails, dark legs, and conspicuous black- and-white wing bars. The Black-and-white Warbler breeds across much of the eastern United States and southern Canada, absent only from parts of the southeast and Midwest. In winter, this species may be found along the coast of the southeastern U.S. from North Carolina to Florida, and along the coast of Texas. South of the U.S., this species is a winter visitor to central and southern Mexico, Central America, the West Indies, and parts of northern South America. Black-and-white Warblers breed in a variety of deciduous or mixed deciduous and evergreen forest habitats, with a preference for mature forests. In winter, this species occurs in numerous kinds of habitats ranging from scrubland to moist tropical forests. Black-and-white Warblers eat small invertebrates, primarily insects (including caterpillars) and spiders. Unusually for a wood warbler, the Black-and-white Warbler feeds by picking prey out of crevices in bark while climbing up the sides of tree trunks and large branches. As this interesting behavior recalls that of a nuthatch or creeper, birdwatchers who believe they’ve caught a momentary glimpse of either may want to consider taking a closer look: they may well have seen a Black-and-white Warbler instead. This species is primarily active during the day, but, like many migratory songbirds, this species migrates at night.
The black-and-white warbler (Mniotilta varia) is a species of New World warbler, and the only member of its genus, Mniotilta.[2] It breeds in northern and eastern North America and winters in Florida, Central America, and the West Indies down to Peru. This species is a very rare vagrant to western Europe.[2]
Relative to other New World warblers, it is not well studied.[3]
The black-and-white warbler is 11 cm (4.3 in) to 13 cm (5.1 in) in length with a mass of 8 g (0.28 oz) to 15 g (0.53 oz) grams.[3][4] Wingspan ranges from 7.1-8.7 in (18-22 cm).[5]
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 to adult females but with less streaking and a more noticeable buffy wash. Juveniles are heavily spotted, and are similar to first fall individuals otherwise.[4]
This species is 12 cm (5 in) long and weighs 11 g (0.39 oz).[6][3] The summer male black-and-white warbler is boldly streaked in black and white, and the bird has been described as a flying humbug.[7] 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).[4][8]
Linnaeus described the black-and-white warbler (Mniotilta varia) in 1766.[9][8] This warbler is a species of New World warbler or wood warbler (family Parulidae), and is the only member of its genus due to its unique foraging adaptations.[3]
It is known to hybridize with the cerulean warbler (Setophaga cerulea) and Blackburnian warbler (Setophaga fusca). The black-and-white warbler is thought to be closely related to the genus Setophaga.[4]
No subspecies are known.[3][4]
The genus name comes from the Ancient Greek mnion, meaning "seaweed", and tillo, "to pluck". Vieillot mistranslated the first word, mnion as "moss". The specific varia is from the Latin varius, meaning "variegated".[10]
The black-and-white warbler is a migratory species, breeding in North America and wintering in North and South America. It is typically found in deciduous forest in its breeding range, but becomes more of a habitat generalist in the non-breeding season.[3]
The black-and-white warbler 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.[3] It has also been noted to winter in shade coffee plantations and gardens.[3][11]
Males are territorial in both their summer and winter habitats.[12][13]
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.[3] The IUCN estimates the extent of occurrence, or range, to be 11,500,000 km2.[9]
This species occurs as a vagrant in Iceland, Ireland, Faeroes, and the UK.[4]
The IUCN classifies the black-and-white warbler as Least Concern due to its large range and population size. However, its population is decreasing.[9] Habitat loss and degradation, especially forest fragmentation, are the main factors contributing to the species’ decline. If habitat loss continues, in either or both summer or wintering habitat, the species may continue to decline in the future.[14][15] Pesticides such as fenitrothion and phosphamidon have contributed to the species’ decline in the 1970s,[16] and others such as chlorinated hydrocarbons may continue to have an effect.[3]
The black-and-white warbler has a high-pitched song, described as a repeating wee-see that is repeated at least 6 times in succession. It has a chip call as well as a seet-seet call that is sometimes given in flight.[4]
Its song is a high see wee-see wee-see wee-see wee-see wee-see or weesa weesa weetee weetee weetee weet weet weet. It has two calls, a hard tick and a soft, thin fsss.[2][6]
This bird feeds on insects and spiders, and, unlike other warblers, forages like a nuthatch, moving up and down tree trunks and along branches.[6]
The black-and-white warbler feeds in a manner similar to a nuthatch or a creeper. It forages on tree trunks and limbs to feed on insects below the bark's surface.[8] Its short legs and long hind toe are adaptations to this foraging method.[8] The black-and-white warbler is unique among warblers in its time spent foraging on tree trunks and inner branches.[3] This bird also gleans, like many warblers, for insects.[4] Its diet is composed of insects and other arthropods, including lepidopteran larvae, beetles, ants, and spiders.[17] During migration and breeding, this warbler relies heavily on lepidopteran larvae.[18]
During migration, the black-and-white warbler sometimes joins mixed flocks to feed.[8]
It breeds in broadleaved or mixed forest, preferably in wetter areas. Black-and-white warblers nest on the ground, laying 4–5 eggs in a cup nest.[2]
The black-and-white warbler is of the first warblers to arrive to its spring breeding grounds.[8] In the southernmost range of its breeding habitat, it 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 display by flapping his wings.[3]
The nest is cup-shaped, often located on the ground among roots or against a tree, or in crevices on tree stumps. The species prefers to nest in damp areas. The nest is constructed 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.[3] The female lays 4-5 eggs,[2] which are light brown and speckled with darker brown. The female begins incubating once the last or second-to-last egg is laid. Incubation lasts 10 to 12 days, and is done solely by the female. During incubation, the female is sometimes fed by the male.
Both parents care for the nestlings. The young fledge after 8 to 12 days, and stay around the nest while they improve their flight ability. During this time, the parents remain nearby.[3]
This species generally produces one brood per year.[19]
Black-and-white warbler nests are sometimes parasitized by the brown-headed cowbird (Molothrus ater).[3][8]
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. This species is a very rare vagrant to western Europe.
Relative to other New World warblers, it is not well studied.
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