Back Bay NWR impoundment pool
Back Bay National Wildlife Refuge
Ecology and Management
Back Bay NWR was established in 1938, and like many Refuges its primary management goal is focused on migratory and wintering waterfowl and shorebirds. The Refuge works to provide quality habitat that maintains or increases existing levels of migratory waterfowl and shorebird use. Sixteen impoundments occur on the refuge including five in the separate “Frank Carter” group. Two additional impoundments occur on the adjacent False Cape State Park, but are managed by Back Bay NWR staff. The impoundments are oligohaline (almost fresh water) and most are surrounded by a network of dirt roads atop their dikes.These management impoundments at Back Bay support a broad array of bird species. Specifically, the impoundments provide habitat for over 30 waterfowl species. Wading bird populations vary with the season. Most species are present only during their migrations and throughout the summer. Impoundment water levels are drawn down during July to provide additional fish and amphibian forage for these birds, particularly young of the year, prior to their migrations. Refuge shorebirds include the sandpipers, plovers, dunlins, knots, yellowlegs, dowitchers, and sanderlings, among others. They utilize the wet mud/sand flats and beach tidal habitats, where they search for the high-protein invertebrate foods they need to sustain them during their exhausting migrations. They use the Back Bay Refuge beach and impoundments vicinities most during their spring and fall migrations. The Refuge draws down the water levels of its 1000-acre impoundment complex to provide them with additional feeding areas during those periods. The secretive group of saltmarsh birds present on the impoundments includes the rails, gallinules, moorhens and coots, among others. King rail and American coot are most commonly heard or seen on bird surveys.
The habitats provided by the impoundments also support many other species, including a diverse and healthy fish community; river otters; and two state rare beetles and two rare moths. The impoundments at Back Bay NWR also support federal threatened (FT) and endangered (FE) species. These include the piping plover (FT), Kemps ridley (FE), loggerhead sea turtle (FT), green sea turtle (FT), leatherback sea turtle (FE), and seabeach amaranth (FT). However, in terms of sea turtles, those that nest here are the loggerheads. Several Kemp’s ridley have been seen since 2012, and occasionally there are green sea turtle. The state endangered eastern big-eared bat is suspected to use Back Bay NWR, but its occurrence has not been confirmed. The State threatened glass lizard was documented on Back Bay NWR during the late 1990s, and the most recent siting was in 2010. The state endangered Eastern tiger salamander is also present on the Refuge.
Several non-native and or invasive species threaten management of the impoundments. The feral hog, feral horse, nutria and resident Canada goose all consume moist soil vegetation that is grown each year in the impoundment complex to feed wintering and migrating waterfowl. If too much browsing on this important resource is allowed to occur, the ability of the Refuge to provide wintering waterfowl foods will be severely reduced. Feral hogs also significantly impact dike slopes and public use areas with their rooting behavior as they seek tubers and other foods below the surface of the ground. Such turned-over ground contributes to soil erosion around dike slopes, and creates a public safety hazard, while also removing the food-plants/vegetative cover.
In terms of management, water levels in the impoundments are drawn down during the spring and early fall months to create shallow mud flats for the shorebird migration. This is during months of late April – May and late August – September. During the summer (July, August) pools are managed for wading/marsh birds are emergent marsh with shallow water and patches of emergent plants.
The Refuge has over 8 miles of dike roads, which form 18 wetland impoundments managed by over 25 water control structures and two pump stations. Two additional impoundments (managed by the refuge) occur in the adjacent False Cape State Park. The impoundments, however, are relatively protected by the Refuge’s barrier dune system.
The Refuge sees approximately 100,000 to 120,000 visitors per year. The Refuge also provides some education opportunities. The trail system around the Refuge headquarters; an outdoor classroom; pond activity pier; and the oceanfront, bay, and impoundment areas all serve as environmental education resources for individuals and groups. A number of self-guided interpretive kiosks and panels are strategically located throughout the Refuge, with the highest concentration in the Refuge headquarters area.
We are grateful to Geralyn Mireles, USFWS Back Bay National Wildlife Refuge, for providing helpful information used on this page.