- 5.1–5.5 in
- 9.1 in
- 0.4–0.7 oz
- Paruline de Swainson (French)
- Verdín de Swainson, Reinita de Swainson (Spanish)
- One of the Swainson's Warbler wintering grounds is in the dry limestone forests of Jamaica. During the dry season some birds have trouble finding food there. Because the Swainson's Warbler digs under the leaf litter for insects, it is less affected by the dryness than birds foraging in the forest canopy or on the surface of the ground.
- The Swainson's Warbler holds a large territory for such a small bird, defending between 3 to 18 ha (7.4-44.5 acres). Measuring exact territory size is difficult, however, because of the extremely dense and vine-entangled habitat used for breeding.
- The Swainson's Warbler flies directly from perch to perch instead of hopping through the branches like most warblers. It often flies directly across its territory, from one side to the other without stopping in between. On the ground it walks rapidly and rarely hops.
- The Swainson's Warbler is commonly found in thickets of giant cane, and some researchers have suggested that the plant is essential for the species to nest. Recent work shows, however, that the warbler nests in lowland areas where cane is rare or absent. More important than the exact type of understory plants present is the presence of a thick understory with vine "tents" and tangles, and small shaded glades carpeted with leaf litter.
- The oldest recorded Swainson's Warbler was a male, and at least 9 years, 11 months old when he was recaptured and rereleased during banding operations in South Carolina.
- Breeds in southern forests with thick undergrowth, especially canebrakes and floodplain forests in lowlands and rhododendron-mountain laurel in Appalachians.
- Winters in tropical scrub, evergreen, and gallery forests.
Insects and spiders.
- Clutch Size
- 2–5 eggs
- Egg Description
- White, usually unmarked, but may have faint reddish brown spotting.
- Condition at Hatching
- Helpless and naked.
Nest a cup of dried leaves, sticks and vines placed low in shrub or vines. Lined with pine needles, hair, grass, Spanish moss, or fern stems.
Forages on ground, probing under leaves and flipping leaves. Frequently sticks its bill into a curled leaf and opens its bill to spread the leaf apart.
Swainson's Warbler populations appeared stable, with a possible increase between 1966 and 2014, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 90,000 with 100% spending part of the year in the U.S., and 30% in Mexico. The species rates a 13 out of 20 on the Continental Concern Score. Swainson's Warbler is a U.S.-Canada Stewardship species and is not on the 2014 State of the Birds Watch List. Extreme habitat specificity puts this species at risk from habitat loss, both on breeding and wintering grounds.
- Brown, R. E., and J. G. Dickson. 1994. Swainson's Warbler (Limnothlypis swainsonii). In The Birds of North America, No. 126 (A. Poole, and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists' Union, Washington, D.C.
- Graves, G. R. 2002. Habitat characteristics in the core breeding range of the Swainson's Warbler. Wilson Bulletin 114: 210-220.
- North American Bird Conservation Initiative, U.S. Committee. 2014. State of the Birds 2014 Report. U.S. Department of Interior, Washington, DC.
- Partners in Flight. 2012. Species assessment database.
- Strong, A. M., and T. W. Sherry. 2001. Body condition of Swainson's Warblers wintering in Jamaica and the conservation value of Caribbean dry forests. Wilson Bulletin 113: 410-418.
- USGS Patuxent Wildlife Research Center. 2015. Longevity records of North American Birds.
- USGS Patuxent Wildlife Research Center. 2014. North American Breeding Bird Survey 1966–2014 Analysis.