Bird GuideWood WarblersSwainson's Warbler

At a Glance

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.
Category
Perching Birds, Wood Warblers
Conservation
Low Concern
Habitat
Coasts and Shorelines, Forests and Woodlands, Freshwater Wetlands
Region
Florida, Great Lakes, Mid Atlantic, Plains, Southeast, Texas
Behavior
Direct Flight, Flitter
Population
160.000

Range & Identification

Migration & Range Maps

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.

Description

5" (13 cm). Heavy-billed and plain for a warbler. Olive-brown back, warmer brown crown, pale eyebrow. Below tinged gray or yellow. Compare to wrens.
Size
About the size of a Robin, About the size of a Sparrow
Color
Brown, Gray, Green
Wing Shape
Rounded
Tail Shape
Notched, Rounded, Square-tipped

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.
Call Pattern
Falling, Flat, Undulating
Call Type
Chirp/Chip, Whistle

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.

Behavior

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.

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.

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.

Climate Vulnerability

Conservation Status

Undoubtedly has declined in many areas with clearing of southern forests. Where habitat remains, still fairly common.

Climate Map

Audubon’s scientists have used 140 million bird observations and sophisticated climate models to project how climate change will affect the range of the Swainson's Warbler. Learn even more in our Audubon’s Survival By Degrees project.

Climate Threats Facing the Swainson's Warbler

Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.

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