Introduction

Swainson’s Warbler, one of North America’s most secretive and least understood avian species, is a medium-sized wood-warbler that breeds primarily in the southeastern United States and winters in the Yucatán Peninsula, Belize, and on Caribbean islands. It is usually associated with swamps and river floodplain forests, hence its generic name, Limnothlypis, meaning “marsh warbler.”

The species was first described by John James Audubon in 1834 from a specimen obtained in South Carolina in 1833 by his colleague the Reverend John Bachman of Charleston. Audubon named the bird after his friend and fellow ornithologist William Swainson, but evidence strongly suggests that the original discoverer of the species was Georgia artist-naturalist John Abbot, who made drawings and watercolors of the bird as early as 1801 (Meanley 1971b, Simpson 1984). According to most accounts, the first nest of the species was collected by Arthur T. Wayne in South Carolina in 1885, but the first discovery of its nest may have been as early as 1846 by Joseph LeConte, scientist and eventual founder of the Sierra Club. Although LeConte never published or reported his historic discovery, his notes from as early as 1846 or 1847 include the description and location of a Swainson’s Warbler nest in Georgia (Simpson and Stephens 1994).

Known to most birders only from its mystic song and fleeting appearances between patches of dense vegetation, Swainson’s Warbler is an extremely difficult species to study. Its dense habitat, retreating habits, and drab coloration discourage even the most persistent field ornithologists. Finding its inconspicuous nests is a formidable task, and many researchers have spent entire field seasons searching for them with little or no success. There are still many gaps in our knowledge of this species, as indicated in this account.

Significant contributions to the understanding of this species have been made by Brooke Meanley (1971b), culminating with the publication of his Natural History of the Swainson’s Warbler in the North American Fauna Series. Much information from that publication and his earlier articles is included in this account.

Swainson’s Warbler breeds and nests in two possibly distinct populations: in the swamps and bottomlands of the South Atlantic and Gulf Coastal Plains, and in the mixed mesophytic forests of the southern Appalachian Mountains. Males typically defend large territories against conspecific males, with the nest often located on the periphery or perhaps even outside the defended territory. Where suitable habitat occurs in patches large enough to support territories of several males, this species occasionally nests in colonies or clusters. Breeding pairs whose initial or second nesting attempt fails may try to renest, but no pair has yet been shown to successfully raise two broods in a season.