Swainson's Warbler

Limnothlypis swainsonii

Order:
Passeriformes
Family:
Parulidae
Sections

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Photos from this Account

Swainson's Warbler (10 April).

A medium-sized, plain wood-warbler with a long, heavy, sharply pointed bill. Upperparts, including wings, are brown or olive-brown, with the crown reddish brown. A prominent white or pale yellow superciliary is present, and lores and postocular streak are brownish. The underparts are yellowish white to white with no streaking. Sexes are similar in appearance. There are no prealternate molts and only slight seasonal variation in appearance due to feather wear.

Juvenile Swainson's Warbler undergoing Preformative Molt (7 July).

Juvenile Plumage is similar to Definitive Basic Plumage, but upperparts and flanks are plainer brown. Supercilium and postocular stripe are indistinct or lacking; upperwing median and greater coverts tipped buff to cinnamon-brown, forming indistinct wing bars. Central underparts more or less clouded with brown. Body feathers (especially undertail coverts) more filamentous than in later plumages due to lower barb density.

Swainson's Warbler undergoing Preformative Molt (26 June).

Bill is pale pinkish buff in hatchlings, becoming darker with age. The Preformative Molt occurs rapidly, completing during and shortly after fledging, and usually includes all body feathers but no remiges or rectrices.

Swainson's Warbler undergoing Preformative Molt (26 June).

Partial molt; usually includes all body feathers and secondary coverts but no alula feathers, remiges, or rectrices. Note difference between rust-toned juvenile feathers and new olive-toned formative feathers.

Formative Swainson's Warbler (11 November).

Very similar to Definitive Basic Plumage and often difficult to distinguish. Best identified by molt limits between replaced formative upperwing greater coverts, contrasting with older and browner retained juvenile primary coverts; retained juvenile outer primaries and rectrices thinner, more pointed, browner, and relatively more worn. Here, the worn and dull juvenile alula is retained and the overall worn look to the primaries and rectrices in November indicates Formative Plumage.

Formative Swainson's Warbler (6 May).

The retained brown primary coverts contrast with the replaced olive-brown secondary coverts, and the rather worn primary and rectrix tips indicate Formative Plumage.

Definitive Basic Swainson's Warbler (14 April).

Crown plain brown, often tinged reddish. Sides of head pale buffy brownish with pale supercilium, dusky triangular spot of in front of eye, and brownish postocular streak. Remaining upperparts and upperwing coverts plain olive; tail plain olive-brown; tertials warmer brown; secondaries and primaries dusky, edged with light brown or olive. Underparts pale dull yellowish or yellowish white, shaded with olive or olive-grayish laterally. Note the lack of contrast between the primary and greater coverts and the very broad primary tips, indicating Definitive Basic Plumage.

Definitive Basic Swainson's Warbler (21 October).

Appearance in fall tends to be duller overall due to duller brown feather veiling; the crown is browner, less reddish, and the breast and flanks more or less clouded with grayish. As the veiling wears off, the plumage becomes brighter by spring.

The head and bill of a male Swainson's Warbler.

The bill is grayish pink; the iris is brown. Sexes are alike in plumage and similar in measurements but birds in the hand during the breeding season can be sexed by the presence of a cloacal protuberance (in males) or a brood patch (in females).

Swainson's Warbler habitat near a nest in an area dominated by eastern hemlock (Tsuga canadensis).

Franklin Gravely Management Area, Pickens County, South Carolina. Photo by Stanlee M. Miller.

Swainson's Warbler habitat with overstory of loblolly pine.

Washington Parish, Louisiana. Photo by Donata Henry.

Young loblolly pine plantations occupied by Swainson’s Warblers in Escambia County, Alabama, June 2012.

Stand height = 9.5 m. Photo by Gary R. Graves.

Young loblolly pine plantations occupied by Swainson’s Warblers in Neshoba County, Mississippi, May 2011.

Stand height = 6.5 m. Photo by Gary R. Graves.

Swainson's Warbler habitat near a nest in an area dominated by rhododendron (Rhododendron maximum).

Franklin Gravely Management Area, Pickens County, South Carolina. Photo by Stanlee M. Miller.

Swainson's Warbler habitat dominated by pawpaw (Asimina triloba).
Swainson's Warbler habitat dominated by vines (Smilax spp.).
Swainson's Warbler habitat dominated by giant cane (Arundinaria gigantea).
Wintering habitat of Swainson's Warbler in Tikal National Biosphere Reserve, Petén, Guatemala.
Wintering habitat of Swainson's Warbler in Tikal National Biosphere Reserve, Petén, Guatemala.
Swainson's Warbler foraging in leaf litter.
Swainson's Warbler singing in the midstory with head thrown back.
Swainson's Warbler bathing.
Swainson's Warbler precopulatory display.
Female Swainson's Warbler on nest.
Swainson's Warbler nest.
Swainson's Warbler nest.

Specimen collected: Mt. Pleasant, Berkeley County, South Carolina; 9 June. Ruler is in cm.; photographer Rene Corado.

Swainson's Warbler clutch.

Specimen collected: Mt. Pleasant, Berkeley County, South Carolina; 9 June. Ruler is in cm.; photographer Rene Corado.

Atypical Swainson's Warbler eggs in nest.

Swainson's Warbler eggs are generally white, but rarely are speckled, like this Swainson's Warbler clutch from St. Francis National Forest, Phillips County, Arkansas.

Female Swainson's Warbler incubating at a Swainson's Warbler nest.
Female Swainson's Warbler incubating at a Swainson's Warbler nest.

White River National Wildlife Refuge, Arkansas, 18 June 2007. Photo by Eric Huskinson.

Newly hatched and hatching Swainson's Warbler young.

White River National Wildlife Refuge, Arkansas, 14 June 2007. Photo by Eric Huskinson.

Swainson's Warbler hatchlings and egg in nest.
Swainson's Warbler nestling.
Swainson's Warbler nestlings in nest.
Swainson's Warbler nestlings in nest.
Adult Swainson's Warbler feeding young at the nest.

Honey Island Swamp, St. Tammany Parish, Louisiana. Photo by Walter Clifton.

Swainson's Warbler nest with 2 Swainson's Warbler eggs (white) and 4 Brown-headed Cowbird eggs (speckled).
Brown-headed Cowbird nestling (right) in a Swainson's Warbler nest with Swainson's Warbler nestling (left).
Swainson's Warbler (cover image).

Recommended Citation

Anich, N. M., T. J. Benson, J. D. Brown, C. Roa, J. C. Bednarz, R. E. Brown, and J. G. Dickson (2019). Swainson's Warbler (Limnothlypis swainsonii), version 3.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.swawar.03