True to its name, the Black and white Warbler (Mniotilta varia) is black and white. This plumage, along with its distinctive habit of creeping along the trunks of trees and large branches like a nuthatch, makes it an easy species to identify. The Black-and-white Warbler has a large distribution nesting from central Canada to the east coast, and south through the eastern United States to eastern Texas. The winter range is very extensive stretching from Florida to northern South America. It is frequently seen during spring and fall migration throughout Tennessee, and is a fairly common summer resident in upland deciduous and mixed forests across the state. Black-and-white Warblers usually arrive by late March and depart by early October.

Bold black-and-white striped plumage, including a white eyebrow line, a striped crown, two white wing-bars, and spotted undertail coverts. The male has a black throat and cheek, while the female has dull whitish cheeks, chin, and throat. Length: 5.25″. Wingspan: 8.25″. Weight: 0.37. The song is a series of high, thin wee-see notes, repeated 5 to 10 times.

Similar Species: Blackpoll Warblers are also black and white, but never creep along tree trunks, and have a solid black cap, and white cheeks. Habitat: Breeding habitat includes mature and second-growth deciduous and mixed forests. Migration habitat includes all types of forests and woodlands, including parks and gardens.

Black and white Warblers eat mostly insects. Moth and butterfly larvae form the bulk of their diet during spring migration and throughout the breeding season. Other arthropod prey includes ants, flies, spiders, click and leaf beetles, wood-borers, leafhoppers, and weevils. They also feed on insects attracted to Yellow-Bellied Sapsucker sapwells.

Nesting and reproduction: Black and white Warblers are among the first warblers to return to their territories in the spring, arriving in late March. Peak egg laying is in early May. Theirs clutch size: Usually 4 or 5 eggs. Only the female incubates the eggs, which hatch after 10 to 12 days. Both adults feed the young. When the young leave the ground-level nest in 8 to 12 days they are unable to fly well, and use their wings to scurry across the ground.

The female usually builds the well-hidden nest on the ground near the base of a tree, rock, or fallen limb. It consists of an open cup made of dry leaves, grass, and bark, lined with finer materials, and concealed from above with dead leaves.

Black and white Warblers crawl along tree trunks and thick limbs as they probe methodically between bark fibers for grubs and insects. Unlike Brown Creepers, which tend to move up a tree as they feed, or nuthatches, which typically move downward, this warbler moves in every direction. They forage on dead limbs and bark as well as gleaning foliage at the tips of branches. Male Black-and-white Warblers arrive in early spring on their forested breeding grounds and set up territories that they defend aggressively, often singing as they chase off intruders. These defensive displays extend well past the time when such behavior has tapered off for other species. A courting male chases potential mates on his territory, perching nearby and fluttering his wings. Once the pair is established, the female leads her partner to likely nest spots at the base of a tree or fallen log, and takes the lead in constructing the well-camouflaged nest.

Status in Tennessee: The Black-and-white Warbler is a fairly common migrant across the state, and a more common summer resident in East, than Middle or West Tennessee. Birds usually arrive by late March and depart by early October. Populations are declining in the state.

Fun Facts about warblers: Fun Facts: The Black and white Warbler has relatively short legs and an unusually long hind toe and claw to help it with its bark-foraging habits. The bill is longer and more curved than most warblers, allowing it to probe deep into bark crevices. When danger approaches, females have been observed to perform a “rodent run” display, in which the bird assumes a hunched posture, and drags its tail as it attempts to distract the would-be predator away from the nest. John James Audubon (1785-1851) labeled his painting of the Black-and-white Warbler, the Black-and-white Creeping-Warbler. The oldest known wild Black-and-white Warbler was 11 years, 3 months old.

Obsolete English Names: black-and-white creeping warbler, black and white creeper, pied creeper, creeping warbler, striped warbler, whitepoll warbler, small-billed creeper. Best places to see in Tennessee: Frozen Head State Natural Area, North Cumberlands WMA, Great Smoky Mountains NP.

Sources: Kricher, J. C. 1995. Black-and-white Warbler (Mniotilta varia). The Birds of North America, No. 158 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists’ Union, Washington, D.C. Nicholson, C. P. 1997. Atlas of Breeding Birds of Tennessee. Univ. of Tennessee Press, Knoxville. Robinson J. C. 1990. An Annotated Checklist of the Birds of Tennessee. Univ. of Tennessee Press, Knoxville. Sibley, D. A. 2000. The Sibley Guide to Birds. A. A. Knopf, New York, NY.