Guide to North American Birds
Conservation status Undoubtedly has declined in many areas with clearing of southern forests. Where habitat remains, still fairly common.
Family Wood Warblers
Habitat Swamps and river floodplain forests. Breeds both in swamps and bottomlands of the southern coastal plains and in moist Appalachian forests. In swamps, prefers large tract with dense understory and sparse ground cover. Found especially in canebrakes and dwarf palmetto. In Appalachians, prefers rhododendron-laurel-hemlock associations or yellow poplar, oak and maple with moderate undergrowth. Winters in woodland undergrowth in tropics.
A shy denizen of southern canebrakes, Swainson's Warbler is more often heard than seen. It spends most of its time on or near the ground in dense cover, walking about in search of insects. Quite plain in appearance, and with a relatively heavy bill, it does not suggest a warbler when it is glimpsed foraging in the undergrowth; however, it may be recognized by its rich musical song, audible from some distance away.

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Feeding Behavior

Forages at a rapid walk in openings in understory, usually on ground or in leaf litter. Probes under leaves by flipping them over, also probes into ground with long heavy bill, and occasionally takes items from tree trunks or makes short flights to catch flying insects. Forages alone in winter or with mate in summer.


Eggs

3, sometimes 2-5. Normally unmarked white, sometimes faintly spotted. Incubated by female, 13-15 days. Male feeds female, but only when she is off the nest. Young: Both parents feed nestlings for 10-12 days. Young then leave nest and follow parents to be fed for another 2-3 weeks. 1 brood per year.


Young

Both parents feed nestlings for 10-12 days. Young then leave nest and follow parents to be fed for another 2-3 weeks. 1 brood per year.

Diet

Mostly adult and larval insects. Feeds on caterpillars, beetles, ants, crickets, grasshoppers, katydids, stink bugs, flies, other insects; also spiders and millipedes. Apparently eats no berries or nectar.


Nesting

Normally males hold very large territories, but in very good habitat will nest in loose colonies. Sings to hold breeding territory and to attract female to territory. Uses visual threat displays to repel rival males. Nest site is usually at edge of dense growth of cane, vines, or rhododendron. Placed near or over water, or up to 4' above ground. These open cup nests are inconspicuous and difficult to locate, even though they are the largest above-ground nests of all North American warblers. Constructed of leaves, sticks, vines, lined with soft material such as pine needles, Spanish moss, hair, grass, and ferns. Female builds nest alone.

Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds

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Migration

Apparently migrates mostly at night. Arrives on breeding grounds later in spring than most other southern warblers. Those wintering in Middle America migrate north directly across Gulf of Mexico.

  • All Seasons - Common
  • All Seasons - Uncommon
  • Breeding - Common
  • Breeding - Uncommon
  • Winter - Common
  • Winter - Uncommon
  • Migration - Common
  • Migration - Uncommon

See a fully interactive migration map for this species on the Bird Migration Explorer.

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Songs and Calls

3 or 4 clear notes followed by several rapid descending notes, described as whee-whee-whee-whip-poor-will; similar to song of Louisiana Waterthrush.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
Learn more about this sound collection.