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 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
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
There are no known negative effects of Mniotilta varia on humans.
We do not know of any way that Mniotilta varia affects humans.
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.
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 )
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 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
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 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.
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 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
