News & Features

The Elusive and Mysterious Sedge Wren

Sedge Wren - PGC photo by Dave Hawkins

The little Sedge Wren is a most peculiar species of songbird. Formerly known as the Short-billed Marsh Wren, it has a broad distribution throughout much of the Americas. In North America, it is a nomadic bird that opportunistically nests in wet areas with fine vegetation — grass and sedge meadows, wetlands, and fields. With the wet summer, there is the potential for Sedge Wrens to colonize places in Pennsylvania that meet their criteria. Some nesting activity has been found in the Southeast, but perhaps there are other nesting events going unnoticed. Now would be a good time to look for this elusive and fascinating tiny songbird, and study its chattering song and plumage characteristics that distinguish it from other little wrens. We also remind birders that good birding etiquette should be part of any rare bird search. Avoid interrupting any breeding activity or nesting potential of Sedge Wrens and refrain from damaging its fragile habitat. Please respect the wishes of any private landowner and avoid trespassing on private property. Keep to the trail and keep an eye on the wrens for a great experience. Go looking for Sedge Wrens this August for an added challenge in Pennsylvania birding. Here is information gleaned about the fascinating Sedge Wren from the Pennsylvania Game Commission website, updated for 2017.

CURRENT STATUS: In Pennsylvania, the Sedge Wren is endangered and protected under the Game and Wildlife Code. It also is a U.S. Fish and Wildlife Service Migratory Bird of Conservation Concern in the Northeast. All migratory birds are protected under the Migratory Bird Treaty Act of 1918.

POPULATION TREND: Sedge Wrens (Cistothorus platensis) may appear and possibly breed in Pennsylvania almost any time from late spring to early fall. They are absent from much of their historic range in the state, even where there is suitable habitat. Sedge Wrens are rare, irregular migrants and breeders, not known to occur at any particular location in Pennsylvania on a regular basis. Despite the species’ reputation as an ephemeral breeding bird and its slipping population across the northeastern United States, evidence of breeding in Pennsylvania increased slightly between the first (1982-1989) and second (2004-2008) Breeding Bird Atlas projects. During both Atlas periods, the Sedge Wren was located most frequently in marshes and wet meadows in Erie, Crawford, and Lawrence counties. Absence from much of its historic range in Pennsylvania and the larger regional decline may be attributable to habitat loss, but could also be related to the difficulty in seeing them in their preferred habitat, dense grass. Sedge Wren was designated threatened in 1985’s Species of Special Concern in Pennsylvania, published by the Pennsylvania Biological Survey. In 2005, the Pennsylvania Game Commission changed its status to endangered from threatened on the advice of the Ornithological Technical Committee of the Pennsylvania Biological Survey. Pennsylvania is at the edge of the breeding range of Sedge Wren but the behavior of this unusual species allows our state to host it in appropriate habitat opportunistically.

IDENTIFYING CHARACTERISTICS: The Sedge Wren, formerly known as the Short-billed Marsh Wren, can best be distinguished from other wrens by its relatively small size and streaked head. It’s only 4½ inches high, has a six-inch wingspan, streaked crown and back, faint buff-colored eye stripes, and a short tail that is often held upright. The best way to detect this miniature marsh-dweller is by its voice. The male’s song is a dry, rapid trill often sung at night. The song begins with two or three sharp introductive notes followed by a rapid, chattering series of trill notes. Individuals apparently improvise songs within a certain pattern.

Nest of a Sedge Wren with side entrance by Joe Kosack, PGC

BIOLOGY-NATURAL HISTORY: The Sedge Wren has a rather unusual lifestyle that is well suited to the transitory nature of its habitat. Sedge Wrens tend to be nomadic, moving from place to place even within the breeding season and rarely occupying locations in consecutive years. Males also may have more than one mate. There is a strong suspicion that Sedge Wrens will nest multiple times in different locations during the extended breeding season. These habits make this little bird difficult to study and understand. In summer, Sedge Wrens are found from southern Saskatchewan and Minnesota across the Great Lake states to the east. Sedge Wrens will nest a second time in different locations often to the south and east of the first nesting location. They winter along the Atlantic and Gulf coasts, as far south as Mexico. Sedge Wrens arrive in Pennsylvania in April and May, and migrate south to brackish coastal marshes from August to October. Sometimes they arrive on breeding grounds in mid- to late-summer apparently after nesting elsewhere. Among the last birds to nest in the state, Sedge Wrens may be found nesting here as late as August. They nest opportunistically in wetland areas or wet meadows and hayfields. Conditions change each year and the birds respond to these changes. A typical clutch of six or seven white eggs is laid in a globular nest built up to two feet off the ground. Like some other wrens, Sedge Wrens build a nest with a side entrance. Young hatch in 12 to 14 days, and leave the nest at two weeks of age. Two broods can be produced each year.

PREFERRED HABITAT: For nesting, Sedge Wrens require damp meadows or marshes where sedges and grasses are interspersed with small shrubs. These wetlands do not need to be large. They apparently don’t do well in cattail marshes, but can be found in flooded hayfields and moist grasslands. Rainfall patterns can have an important effect on its distribution in any year.

Sedge Wren breeding range in Pennsylvania (2009) by Cathy Haffner

REASONS FOR BEING ENDANGERED: Sedge Wrens are rare throughout their range. They used to be found nesting in scattered locations across Pennsylvania. Over the past several decades, however, they have disappeared from many of their former haunts, and numbers have dropped significantly in others. The loss of habitat and changing agricultural practices are thought to be responsible for this decline. Urbanization and drainage of moist fields and meadows are other negative factors for Sedge Wrens which can nest in areas where there is a lot of human activity as long as the habitat exists. A map of the breeding range as of 2009 is provided in this story, but this will be constantly revised as we learn more about Sedge Wren incursions into Pennsylvania.

MANAGEMENT PROGRAMS: The specific locations where Sedge Wrens currently nest in the state need to be determined and then, where feasible, protected. The locations probably change from year to year, depending on the pattern of rainfall and the local conditions. In general, wetlands deserve more proactive protection on private lands, including acquisition or voluntary techniques to protect habitat. Certain grassland and wetland management techniques may be favorable to this species. The planting of warm season grasses, preventing encroachment of woody vegetation into idle grasslands, control of invasive exotic plants, avoidance of pesticides, and delaying mowing of hay are among those practices that would benefit this species. More sedge meadows could be created or restored with specific management including prescribed burning and flooding of grassland habitat. A few locations where it has nested are designated as Important Bird Areas in our state.

 

Sources:

Herkert, J. R. and D. E. Kroodsma, and J. P. Gibbs. 2001. Sedge Wren (Cistothorus platensis), No. 582, In The Birds of North American, (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists’ Union, Washington, D.C.

Leberman, R. C. 1992. Sedge Wren, Cistothorus platensis, Pages 256-257, In Atlas of Breeding Birds in Pennsylvania. (D. W. Brauning, Editor) Univ. of Pittsburgh Press, Pittsburgh, PA.

U.S. Fish and Wildlife Service. 2008. Birds of Conservation Concern 2008. United States Department of Interior, Fish and Wildlife Service, Division of Migratory Bird Management, Arlington, Virginia. 85 pp.

Wilhelm, G. 2012. Sedge Wren, Cistothorus platensis, Pages 314 – 315 In Second Atlas of Breeding Birds in Pennsylvania (A. M. Wilson, D. W. Brauning, and R. S. Mulvihill, editors). The Pennsylvania State University Press, University Park, Pennsylvania.

Suggested further reading:

Bent, A. C. 1964. Life histories of North American nuthatches, wrens, thrashers, and their allies. Dover Publications, Inc., New York, New York. 475 pages.

Burns, J. T. 1982. Nests, territories, and reproduction of Sedge Wrens (Cistothorus platensis). Wilson Bulletin 94(3): 338-349.

Burt, W. 2001. Rare and Elusive Birds of North America. Universal Publishing, New York, NY.

Dechant, J. A., M. L. Sondreal, D. H. Johnson, L. D. Igl, C. M. Goldade, B. D. Parkin, and B. R. Euliss. 2003. Effects of management practices on grassland birds: Sedge Wren. Northern Prairie Wildlife Research Center, Jamestown, ND. Northern Prairie Wildlife Research Center Online.(Version 12DEC2003).

Gross, D. A. and C. D. Haffner. 2009. Wetland bird communities: boreal bogs to open water. In Avian Ecology and Conservation: A Pennsylvania Focus with National Implications (S. Majumdar, T. Master, M. Brittingham,R. Ross, R. Mulvihill, and J. Huffman, Eds.). The Pennsylvania Academy of Science, Easton, Pennsylvania. 350 pp.

NatureServe. 2009. NatureServe Explorer: An online encyclopedia of life. Version 7.1. NatureServe, Arlington, Virginia. Search for “sedge wren”.

PGC-PFBC (Pennsylvania Game Commission and Pennsylvania Fish & Boat Commission). 2015. Pennsylvania Wildlife Action Plan, 2015-2025. C. Haffner and D. Day, editors. Pennsylvania Game Commission and Pennsylvania Fish & Boat Commission, Harrisburg, Pennsylvania.

Rich, T. D., C. J. Beardmore, H. Berlanga, P. J. Blancher, M. S. W. Bradstreet, G. S. Butcher, D. W. Demarest, E. H. Dunn, W. C. Hunter, E. E. Inogo-Elias, J. A. Kennedy, A.M. Martell, A. O. Panjabi, D.N. Pashley, K. V. Rosenberg, C. M. Rustay, J. S. Wendt, T. C. Will. 2004. Partners in Flight North American: Landbird Conservation Plan, Cornell Laboratory of Ornithology, Ithaca, New York.

Tiner, R. W. Jr. 1984. Wetlands of the United States: current status and recent trends. National Wetlands Inventory. U. S. Fish and Wildlife Service, Washington, D.C.

U.S. Geological Survey. Northern Prairie Wildlife Research Center website.

By Cathy Haffner and Doug Gross, Pennsylvania Game Commission

Dickcissel , another prairie bird that invades Pennsylvania in late summer, by Marc Favre