The marsh antwren is an insectivorous bird in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds". It is endemic to southeastern Brazil.
Region
Southeastern Brazil (Atlantic coastal plain)
Typical Environment
Occupies dense emergent wetlands, especially cattail- and sedge-dominated marshes along the coastal plain. It favors patches with standing or slow-moving water, floating vegetation, and thick tangles of stems where it can forage and nest. The species is closely tied to Typha and other robust reeds and sedges, using them for cover and as foraging substrates. It generally avoids open water and heavily disturbed reedbeds. Fragmentation of suitable marshes limits movements between sites.
Altitude Range
Sea level to 100 m
Climate Zone
Subtropical
Ease of Keeping
Beginner friendly: 1/5
Described only in the 1990s, the marsh antwren has a very small, fragmented range in southeastern Brazil and is highly dependent on intact marshes. It often sings in duets, with pairs maintaining year‑round territories in dense cattail stands. Ongoing drainage, burning, and development of wetlands threaten its habitat, contributing to its endangered status.
Temperament
skulking and territorial
Flight Pattern
short rapid wingbeats with brief hops between stems
Social Behavior
Typically found in pairs or small family groups that defend small territories year-round within dense marsh. Nests are cup-shaped and placed low, suspended among reeds or sedges above water. Both sexes participate in nest building and care, and pairs often maintain close contact while foraging.
Migratory Pattern
Resident
Song Description
The song is a quick, high-pitched series of chips and trills delivered from within cover, often given antiphonally by a pair. Contact calls are sharp, dry tzet notes, with scolding rattles when disturbed.
Plumage
Compact antwren with a long, narrow bill and a frequently cocked tail; plumage contrasts strongly between sexes. Males are dark slaty to blackish with conspicuous white spotting and wing bars; females are warm brown above with buffy to cinnamon underparts and paler throat.
Diet
Feeds primarily on small insects and other arthropods, such as beetles, hemipterans, flies, caterpillars, and spiders. It gleans prey from reed stems, leaf bases, and low foliage, and occasionally snatches items from the water surface or floating vegetation. Foraging is meticulous and close to cover, with frequent tail-cocking and short hops.
Preferred Environment
Forages within dense cattail and sedge stands, often 0.5–2 m above the water, and along edges of channels and lagoons. It favors microhabitats with a complex tangle of stems, which provide both foraging surfaces and concealment.
