Brown above; pale gray to buffy below; bold buffy eyebrow; dark thin eye stripe. 14 cm (5.5 in) in length. Long and pointed bill.
The breeding season begins in early May, peaks later that month, and extends until early July. Nesting habitat is areas with dense understories like wet deciduous forests and canebrakes (stands of a native bamboo species). The nest is usually 2-6 feet ( m) above the ground. The female builds the cup-shaped nest out of leaves and other plant materials. The female lays 2-5 (usually 3) eggs that she incubates for 13-15 days. The young are altricial and fledge 10-12 days after hatching. The fledglings remain with the adults for an additional 2-3 weeks.
Wintering and migration habitat is similar to the breeding habitat. The Swainson's Warbler is usually in habitat with a dense understory. The diet consists mainly of insects, spiders, and millipedes. It searches for food on the ground, moving the leaf litter and looking around downed material and the bases of trees and shrubs. This species is migratory.
During the breeding season, the Swainson's Warbler occurs in appropriate habitat across the southeastern United States. Wintering birds are found in the West Indes, Mexico, Belize, and Honduras. The largest number of wintering birds are in Jamaica. The Swainson's Warbler can be found throughout the state of Georgia during the breeding season, although they are uncommon.
The Swainson's Warbler has declined in portions of its range. These declines are attributed to habitat degredation (removal of canebrakes) and parasitism by the Brown-headed Cowbird, which lays its eggs in other birds' nests so that the host parents to raise its young instead of or in addition to their own. This species is not listed as Threatened or Endangered in any portion of its southeastern range.
The species most similar to the Swainson's Warbler is the Worm-eating Warbler. The Worm-eating Warbler has a bold buffy and brown head stripe pattern.