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    Marsh Wren Life History

    Habitat

    Habitat Marshes

    Marsh Wrens occupy wetlands filled with cattails, sedges, bulrushes, and Phragmites as well as cordgrass-filled saltmarshes year-round. In the winter they also use brushy thickets near wetlands, tidal saltmarshes, and weedy agricultural canals.

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    Food

    Food Insects

    Marsh Wrens pick insects and spiders from stems and leaves of marsh vegetation. They tend to forage close to water, but occasionally fly up to catch a passing insect.

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    Nesting

    Nest Placement

    Nest Shrub

    Males build several nests within their territory, in cattails and bulrushes around 2–5 feet above the ground.

    Nest Description

    Males construct a dome-shaped nest with strips of cattail, sedges, and grasses. The nest is oblong with a small hole at the top and an enclosed cup at the bottom. The nest is about 7 inches tall and 5 inches wide. Females line the nest with strips of grass, sedge, cattail down, feathers, and rootlets.

    Nesting Facts
    Clutch Size:3-10 eggs
    Number of Broods:1-2 broods
    Egg Length:0.6-0.7 in (1.4-1.8 cm)
    Egg Width:0.4-0.6 in (1.1-1.4 cm)
    Incubation Period:12-16 days
    Nestling Period:13-15 days
    Egg Description:Brown with dark spots.
    Condition at Hatching:

    Helpless with wisps of down.

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    Behavior

    Behavior Ground Forager

    Marsh Wrens cling to stems of wetland vegetation, often with each foot on a different stalk shimmying up and down and belting out series of gurgling, buzzy trills. They tend to stay down in the reeds, but males sometimes pop up to sing on taller stems especially early in the breeding season. Displaying males also fly weakly above the marsh, fluttering downwards and dropping straight back into the reeds. Adults often return to the same breeding territories year after year. Males arrive on the breeding grounds first and begin building several dome-shaped nests. When a female arrives, he cocks his tail and sings. He then escorts her around to his nests, bowing and holding up his tail. Once the female selects the nest they both aggressively defend the territory, but males don't stick with just one female; they frequently mate with others. Males and females also destroy the eggs and nestlings of other Marsh Wrens and nesting birds, perhaps in a fight over resources.

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    Conservation

    Conservation Low Concern

    Marsh Wrens are common and their populations increased by 130% between 1966 and 2015, according to North American Breeding Bird Survey. The estimated global breeding population is 9.4 million. The species rates a 7 out of 20 on the Continental Concern Score, which means it is not on the Partners in Flight Watch List and is a species of low conservation concern. Although populations appear stable, like other species that rely on marsh habitat, draining and filling of marshes could be problematic for Marsh Wrens.

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    Credits

    Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.

    Kroodsma, Donald E. and Jared Verner. 2013. Marsh Wren (Cistothorus palustris), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

    Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

    Pieplow, N. (2017). Peterson field guide to bird sounds of eastern North America. Houghton Mifflin Harcourt Publishing Company, NY, USA.

    Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

    Sibley, D. A. 2014. The Sibley guide to birds, second edition. Alfred A. Knopf, New York, USA.

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