Prairie Warbler

Dendroica discolor

Howard B. Eskin
  • PARULIDAE
  • Wood Warblers
  • 1.4 million

Contrary to what its name suggests, the warbler does not occur in prairie habitats but rather is a bird of shrubby fields, early regenerating forests, and other successional habitats. The Prairie Warbler breeds in southeastern and central-eastern United States and winters in the southern United States, the West Indies, and coastal Central America. The species has shown rather steep declines since the 1960's.

Identification
A 4.5-inch long bird that often bobs its tail, the Prairie Warbler shows a distinct facial pattern with a yellow eyebrow and a dark half-circle on a yellow cheek in all plumages. A spot of black on the lower neck is also evident. The underparts are all yellow, with dark streaking on the flanks. Adult females are similar to males, only paler. Most spring and fall adults have chestnut markings on the back.

Distribution and Population Trends
The Prairie Warbler breeds in southeastern and south-central United States, as far north as New England, and south into Florida. Winters mostly in the West Indies, but also in coastal Florida and coastal Central America including parts of Belize and Costa Rica. It is also a rare, but regular winter visitor in Georgia, South Carolina, and North Carolina. Many Audubon Important Bird Areas host breeding populations of this species including New York's Long Island Pine Barrens and Northern Shawangunk Mountains IBAs and North Carolina's Alligator River National Wildlife Refuge IBA.

A bird of early successional habitats, the Prairie Warbler experienced a population increase as deciduous forest was cleared in the United States during colonial times but Breeding Bird Surveys (BBS) show recent declines in most of the bird's range. Between 1966 and 1993, BBS data show a 44 percent decline of the Prairie Warbler in Midwestern states. Declines have occurred in Florida since 1971; the subspecies, Dendroica discolor paludicola is listed as a species of special concern there. Breeding populations of the Prairie Warbler have also declined significantly in Michigan since 1970 where the species is now listed as state-endangered.

Ecology
The Prairie Warbler breeds in shrubby habitats including those in southern pine forest, mangroves, pine and scrub oak barrens, and regenerating forest. Interestingly, the species has also been reported breeding in closed canopy forests in Virginia. The cup-shaped nest, made of plant fibers and other materials, is placed in a shrub or sapling roughly one-to-ten-feet off the ground. Incubation occurs for 11 to 15 days; young fledge when they are about 8-to-10-days old. Of 336 nests found in Indiana, 27 percent were parasitized by cowbirds. Female Prairie Warblers have been known to desert their nests if parasitized. Cowbirds will also damage host eggs. The Prairie Warbler eats mostly insects and spiders, but will also take mollusks and sometimes fruit and other vegetative matter. Fall migration begins in September, and the species returns to its breeding grounds beginning in March.

Threats
Habitat loss and fragmentation are the two major threats. Prairie Warbler is among a suite of bird species of shrubby habitats that have shown some of the greatest declines of any habitat group. Destruction of mangrove forests for development in Florida is contributing to the decline there as well as encouraging increased parasitism from Brown-headed Cowbird, and to a lesser extent, Shiny Cowbird. Habitat loss in the wintering range due to cutting wood, development, and agriculture may also be tied to this species' decline. Since the Prairie Warbler has a rather limited winter range, destruction that occurs there could devastate some local populations.

Conservation
As awareness continues to increase towards managing for the needs of species inhabiting shrubby, early successional habitats public and private land managers have begun using a variety of management tools including prescribed burns in fire-dependent habitats, mechanical removal of vegetation to mimic disturbance, and other activities. Many scrub oak-pine barren ecosystems in the eastern U.S., which typically harbor significant populations of Prairie Warblers, have been the focus of intensive protection efforts by state and local governments and NGO's, particularly The Nature Conservancy. In these areas, much land has been purchased and often regulations have been implemented to reduce the impacts of development. Prescribed burns continue to be an actively used tool in these fire-evolved ecosystems.

What Can You Do?
Audubon's Important Bird Area program is a vital tool for the conservation of Prairie Warbler as well as other species. To learn more about the Important Bird Areas program and how you can help, visit: http://www.audubon.org/bird/iba/.

Support local land trusts, government agencies, and other organizations working to preserve pine barrens and other shrub habitats in your area. Contact your state Important Bird Areas coordinator (http://www.audubon.org/bird/iba/state_coords.html) to find out if there are sites in your area important for Prairie Warblers that need increased protection.

U.S. National Wildlife Refuges provide essential habitat for Prairie Warbler, and a great number of other species throughout the U.S. and its territories. Unfortunately, the refuge system is often under-funded during the U.S. government's budgeting process. To learn more about how you can help gain much needed funding for U.S. National Wildlife Refuges, visit: http://www.audubon.org/campaign/refuge_report/

Information on where Prairie Warblers occur and in what numbers is vital to conserving the species. Help in monitoring this and other species by reporting your sightings to eBird. A project of Audubon and the Cornell Lab of Ornithology, eBird is the world's first comprehensive on-line bird monitoring program: http://www.audubon.org/bird/ebird/index.html.

References
Cooper, J.L. 2000. Special animal abstract for Dendroica discolor. Michigan Natural Features Inventory. Lansing, MI. 3 pp.

Dunn, J. and K. Garrett. 1997. Peterson Field Guide: Warblers. Houghton Miffllin. New York.

Nolan, V. Jr., E. D. Ketterson, and C.A. Buerkle. 1999. Prairie Warbler (Dendroica discolor). In The Birds of North America, No. 455 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists' Union, Washington, D. C.

Southwell, D. K. 2001. Conservation Assessment for Prairie Warbler. Eastern Region of the U.S. Forest Service, Milwaukee, WI. 18 pp.