The Great Cypress Swamp is one of the largest contiguous areas of forest on the Delmarva Peninsula. Located at the headwaters of the Pocomoke River, the swamp has 600ha in Worcester Co., Maryland and 4400 ha in Sussex Co., Delaware. This IBA also includes the floodplain forests flanking the Pocomoke River south of the swamp to Highway 50. The swamp, once dominated by Atlantic white cedar and bald cypress, is now dominated by seasonally flooded forest of loblolly and pond pine and hardwoods, including red maple, sweetgum, black tupelo and black gum. There are also areas of dry upland forest. The shrub layer is dense in places, including in areas recently disturbed by southern pine beetle infestations ? a dense shrub layer improves the habitat for Forest-Interior Dwelling Species of bird. Much of the area is owned and managed by Delaware Wild Lands, Inc. and is designated as the Great Cypress Swamp Conservation Area. Maryland DNR owns some portions of the site in Worcester County.
The Great Cypress Swamp has been identified as an IBA due to its diverse community of Forest-Interior Dwelling Species (FIDS) and large populations of several at-risk species from within the FIDS species assemblage. Detailed information of this site?s birdlife has been provided by an in-depth bird study (Heckscher 2000) that counted breeding birds at 75 points throughout the swamp. The FIDS community here is one of the most diverse on the Delmarva peninsula, with 20 species regularly breeding of 24 species found on Maryland?s coastal plain. Among the at-risk species are four on the Audubon/American Bird Conservancy WatchList (Yellow category), Wood Thrush, Prothonotary Warbler, Swainson?s Warbler and Kentucky Warbler. Prothonotary Warblers ranked 4th in abundance of all birds found in Heckscher?s study, indicating a large and regionally important population of this declining species. This site represents the most northerly breeding location of Swainson?s Warbler with just one or two pairs present. Another at-risk species, Worm-eating Warbler, was the most abundant bird found by Heckscher?s study and breeding densities at this site are perhaps the greatest recorded anywhere.