[order] Passeriformes | [family] Parulidae | [latin] Mniotilta varia | [UK] Black-and-white Warbler | [FR] Paruline noir et blanc | [DE] Kletterwaldsänger | [ES] Chipe Rayado | [IT] Parula bianca e nera | [NL] Zwart-witte Zanger

Zwart-witte Zanger determination

copyright: ProAves

Slightly smaller than Blackpoll Warbler, with subtly different structure: rather longer bill with noticeably sharp culmen, shorter square tail, and long toes. Rather small but lithe, bark-creeping Nearctic warbler, with black upperparts striped white, and white underparts streaked black; white central crown-stripe diagnostic.

Breeds across cool to warm temperate Nearctic lowlands, on hillsides or ravines in all woodland types from mature deciduous or mixed stands to (more locally) northern conifer forests and also second growth. Forages on main branches or trunks of trees, rather than in foliage.

Breeds in North America east of Rocky Mountains, from north-east British Columbia and south-west Mackenzie east to Newfoundland, south to eastern Texas and central Alabama. Accidental. Iceland, Faeroes, Britain, Ireland.

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.

This species has a large range, with an estimated global Extent of Occurrence of 5,400,000 km². It has a large global population estimated to be 14,000,000 individuals (Rich et al. 2003). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern. [conservation status from birdlife.org]

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.

Migratory. Winters from northern Mexico and extreme south and south-east of USA south through Central America and West Indies to north-west South America (Venezuela to northern Peru). Probably the most widely common parulid warbler across its winter range. Southward movement extends from Rockies to Atlantic, and even to Bermuda, continuing south through Mexico and Central America as well as across Gulf of Mexico and through Florida. Spring migration is reverse of that in autumn, including both trans- and circum-Gulf movements, on broad front. Rare autumn vagrant to Atlantic seaboard of west Palearctic, mainly Britain and Ireland where 11 records up to 1995, majority September-October, but noted also March and December.