Marsh Wren

The Marsh Wren is a small, feisty wren tightly bound to wetland vegetation, showing a streaked brown-and-black back, plain warm-brown crown, bold white eyebrow stripe, and pale underparts. Its short, often cocked tail and constant activity make it a lively presence within its reedy habitat, though its skulking behavior means it is often heard well before it is seen.

A distinctive aspect of Marsh Wren biology is the male's habit of building numerous globe-shaped "dummy" nests within his territory — often five or more — in addition to the one nest the female ultimately selects and finishes lining for egg-laying, a behavior thought to help defend territory and possibly confuse predators.

Key Field Marks

• Streaked black-and-white patch on the upper back — a key diagnostic mark
• Bold white eyebrow stripe
• Plain, unstreaked brown crown
• Short tail, often cocked upward
• Skulking behavior within dense marsh vegetation

Similar Species

• Sedge Wren: smaller, with a finely streaked (not plain) crown and a less bold eyebrow, and prefers drier sedge meadows rather than deep cattail marsh.
• House Wren: lacks the bold white eyebrow and back streaking, and occupies drier upland habitat.
• Bewick's Wren: longer-tailed with white tail spots, found in brushy uplands rather than marsh.

Habitat

Marsh Wrens are closely tied to freshwater and brackish marshes with dense stands of cattails, bulrushes, or reeds, and are rarely found far from such wetland vegetation.

Range

The species breeds across much of North America, from southern Canada through the northern and western United States, with additional populations along both coasts and wintering birds found across the southern United States and Mexico.

Migration

Northern and interior populations are migratory, wintering in the southern United States and Mexico, while some coastal and southern populations are largely resident year-round.

Behavior

Marsh Wrens are active and pugnacious, aggressively defending nesting territory and sometimes destroying the eggs of neighboring wrens or other marsh-nesting birds; they tend to stay low and hidden within dense marsh vegetation.

Voice

The song is a loud, gurgling, mechanical-sounding series of trills and rattles, often given persistently, including at night; males may know dozens of distinct song types.

Feeding

Diet consists almost entirely of insects and spiders gleaned from marsh vegetation, sometimes including aquatic insects near the water's surface.

Nesting

Males build multiple globe-shaped nests woven from marsh vegetation and attached to reeds or cattails above water, of which the female selects one to line and use for egg-laying; the surplus "dummy" nests may help deter predators or rival males. Clutches typically number 3-10 eggs.