Profile of the Wood-Warblers - Wood-Warbler Family Parulidae
Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Parulidae
Genera in the U.S. & Canada: 16
Species in the U.S. & Canada: 53
Example species: Black and White Warbler (Mniotilta varia)
Appearance
Wood-warblers are small to medium-size songbirds with thin, pointed bills, short wings, and slightly flattened heads. Distinguishing field marks vary between species, but may include contrasting wingbars, tailspots, eyestripes, ear patches, and streaked breasts. Spring arrivals sport distinctive patterns and bright colors including yellow, olive, black, gray, blue, white, orange, and red.
Sexual dimorphism in the appearance of wood warblers varies considerably between species. Male wood-warblers typically display brighter spring (alternate) plumage than females, juveniles, or first-year birds, but autumn (basic) plumage in all age and sex groups can appear confusingly similar within and between species. Although not as difficult to distinguish as some flycatchers or sandpipers, birders often lump autumn wood-warblers into the broad "confusing fall warbler" category.
Habitat
Most wood-warblers in the U.S. and Canada are seasonal migrants, wintering in the southern U.S., Central America, the West Indies, and South America. Wood-warbler diversity reaches the highest in northeastern forests – from the Great Lakes east to New England and the Maritime Provinces, and south into the Appalachian Mountains. Fewer species breed in western North America, primarily in montane and coastal areas.
Wood-warblers breed in forested habitat, attaining the highest species diversity in forests with both hardwood and coniferous components. Outside the breeding season and during migration, wood-warblers occupy a wider range of habitats including open, disturbed areas.
Behavior
Usually only the males sing, producing a range of songs from simple and non-melodious songs, to those with songs consisting of high-pitched trills and inflections. Wood-warblers are generally very active birds, and represent the dominant feature of mixed-species flocks outside of the breeding season. Some wood-warblers defend winter and migration territories, while others will flock with a wide variety of other species, including sparrows, tanagers, vireos, and grosbeaks.
Reproduction
Most wood-warblers defend exclusive territories and mate monogamously. On average, males arrive a week earlier than females to the breeding habitat, whereupon they claim territories with constant singing. After their arrival and courtship, females construct small, open cup nests from grass, leaves, and bark. Nests are lined with softer materials such as moss, and placed in vegetation or on the ground. Many species nest on the ground, including some that spend considerable time in forest canopies. Many species of wood-warblers suffer from high rates of nest parasitism from cowbirds.
Diet
Wood-warblers are primarily insectivorous, actively gleaning larvae and arthropods from vegetation. Some species also consume fruit and nectar. Wood-warblers reduce foraging competition between species by segregating different sections of tree canopies between species.
Migration
A few populations maintain year-round residency in the southern U.S., but most species are Neotropical migrants. Wood-warbler migration between northern breeding habitat and southern wintering grounds represents a marvel of the natural world. These tiny birds (0.2–0.7 oz; 6-20 g) travel thousands of kilometers twice a year, overcoming many physical, and weather-related obstacles along the way. Most travel during the night, and many individuals perish along the way. Major migration routes from North America to southern destinations (and back again) funnel through Florida, the Yucatan Peninsula, eastern Mexico, and the southwestern deserts.
