Importance to waterfowl
Lower Southeastern Coastal Plain
Mid-winter survey data for the Atlantic Flyway suggest a long-term decline in the number of most species of wintering waterfowl (Steiner 1984, Hindman and Stotts 1989). The decline is probably a function of multiple, interactive factors, but loss of aquatic vegetation, particularly in the Chesapeake Bay system likely is a significant factor. The bays and sounds of North Carolina are important to a number of dabbling and diving ducks, Canada geese, and tundra swans. Diving duck use of this area increased as habitat quality in the Chesapeake Bay system declined. North Carolina now winters up to 75% of the Atlantic Flyway canvasbacks, large numbers of the Atlantic subpopulation of Canada geese, and nearly the entire population of eastern tundra swans. Geese and swans in particular have adapted to field feeding on waste grain, no longer extensively foraging on aquatic vegetation in shoals and bays. Also, most of the American wigeon that once wintered in the Chesapeake Bay have shifted southward to the North Carolina bays and sounds to take advantage of available aquatic vegetation. The North Carolina bays and estuaries also are significant migration and winter habitat for lesser scaup, brant, and several species of sea ducks.
Numbers of waterfowl wintering in South Carolina and Georgia also have declined in recent years. This decline is perplexing in that, in general, habitat quality and quantity do not appear to have suffered a similar decline. The decline may be related to the overall decline of waterfowl in the Atlantic Flyway where habitat loss, alteration and degradation have been substantial. Alternatively, it has been suggested that many birds have shifted toward more inland habitats associated with major reservoirs where they are not counted during traditional mid-winter inventory flights. Nonetheless, coastal impoundments still winter several hundred thousand waterfowl, particularly green-winged teal, northern shovelers, American wigeon, northern pintails, wood ducks, and mallards, totaling about 30% of the birds typically found in the Atlantic Flyway. Diving ducks, especially ring-necked ducks and lesser scaup, winter in bays and sounds, but in relatively smaller numbers (generally <100,000) compared to North Carolina's (Gordon et al. 1989, Hindman and Stotts 1989).
Overall, this region is most important as winter habitat for tundra swans, Canada geese, and most species of dabbling and diving ducks common to the southern Atlantic Flyway. The SCP wetlands provide winter habitat to at least 50% of the waterfowl in the Atlantic Flyway. It has secondary importance to migrant lesser scaup, most of which winter in Florida. Factors limiting waterfowl use of habitat within the SCP are unclear. Foraging habitat may well be limiting overall, but before conclusions can be drawn the amount of foraging habitat and its value in terms of duck use days (energetic model) must be quantified. Wintering distributions of waterfowl in the Atlantic Flyway in general appear to have shifted, with a net decline in the number of birds using the flyway. Notable decreases have occurred in the Chesapeake Bay and South Carolina. Causes are unclear, but could relate to foraging habitat limitations caused by habitat loss and degradation. Also, waterfowl distributions may have been affected by inland or northward shifts of some species (mallards in particular) related to an increase in available waste grain and open water at more northern latitudes or in association with major inland reservoirs located in the Upper Southeastern Coastal Plain. Disease, severe weather, and other potential limiting factors are not generally significant problems.
Upper Southeastern Coastal Plain
Depending on their state of succession, beaver ponds can provide abundant food to migrating and wintering wood ducks, mallards, ring-necked ducks, hooded mergansers and limited numbers of other species. Beaver ponds provide very important habitat for breeding wood ducks and hooded mergansers (Arner and Hepp 1989). Minor alluvial floodplains throughout this portion of the region occasionally to regularly flood and provide habitat for wood ducks, mallards, gadwall, wigeon, ring-necked ducks, and limited numbers of other species.
Reservoirs provide an undetermined amount of foraging habitat for waterfowl throughout this region. For example, Eufaula NWR, which was created as mitigation for reservoir construction on the Chattahoochee River in Alabama and Georgia, typically over-winters 5,000-10,000 ducks, mostly mallards, green-winged teal, wood ducks, ring-necked ducks and American wigeon. Also on the Chattahoochee River, Lake Seminole in southern Georgia provides winter habitat for an average of 5,000 canvasbacks and approximately 5,000 to 25,000 ring-necked ducks, many of which feed on exotic hydrilla (Georgia DNR unpubl. data). Exotic plants, particularly hydrilla and Eurasian milfoil have become important foods in some southern reservoirs, particularly for gadwall, wigeon, ring-necked ducks, lesser scaup and canvasbacks (Johnson and Montalbano 1987, 1989). There has been a significant decline in exotic vegetation (i.e., hydrilla) on many of these southern reservoirs - Lakes Marion and Moultrie in SC, Lake Seminole (GA/FL), Lake Okeechobee and many others in FL. Aggressive control programs (herbicide and grass carp) are conducted by most of the southern states. In FL and SC, laws mandate control of exotic vegetation. However, there is evidence in FL that hydrilla is becoming resistant to herbicides and they expect to see increases throughout the state.