American Black Duck (Anas rubripes)
Perhaps no other species of waterfowl symbolizes the Atlantic Flyway more than the American black duck. Historically, it was one of the more abundant puddle duck species on the East Coast. Despite dramatic population declines during the past 50 years, the black duck remains an important and prominent species. The black duck has been identified in the North American Waterfowl Management Plan as a species of priority concern, and the Black Duck Joint Venture was developed to help draw attention to research and management.
There are a number of factors that may be contributing to the decline of the black duck. These include changes in breeding and wintering habitats, hybridization and competition with mallard ducks, environmental contaminants, over-harvest, and poor productivity. A variety of research projects are being conducted to assess these factors, including the following research in Virginia.
Winter Black Ducks
The Chesapeake Bay and the Eastern Shore of Virginia are important wintering areas for black ducks. There are approximately 220,000 black ducks counted in the mid-winter survey throughout the Atlantic Flyway and approximately 20,000 of those are counted in Virginia. There is uncertainty as to how much habitat is required for wintering black ducks, and whether wintering, breeding, or migration habitats are limiting.
Satellite Telemetry Study
To shed some light on these issues, the Virginia Department of Game and Inland Fisheries (VDGIF) is conducting a satellite telemetry study that will obtain information on large-scale movement patterns including migration routes, timing of migration, staging and stop-over areas, winter habitat use and breeding grounds affiliations.
In the winter of 2006-07, VDGIF captured 8 black duck hens along the Eastern Shore of Virginia and equipped them with satellite transmitters. These transmitters emit a signal that is received by satellites orbiting the earth. This information is relayed back to receiving stations on the ground and then to our biologists via the Internet. You can track their movements and read about the habitats they are using along the way by clicking the provided links.
This study is being conducted in cooperation with a companion study on black ducks being led by Ducks Unlimited (DU) and Southern Illinois University (SIU). A graduate student working on the Eastern Shore of Virginia is evaluating food resources available to black ducks, and is using conventional VHF radio telemetry to monitor local habitat use by female black ducks during the wintering period. Black ducks were captured at the same sites as those where satellite transmitters were deployed. For more information on this aspect of the black duck research please visit Ducks Unlimited's Web site.
In the winter of 2007-08, the satellite telemetry portion of the study was expanded. In Virginia, we equipped 23 black duck hens with satellite transmitters, 13 of these were provided by VDGIF and 10 were provided by Ducks Unlimited. Satellite transmitters were again put on female black ducks on the Eastern Shore, and in addition, some were put on female black ducks on the western side of the Chesapeake Bay. Check our tracking maps to find the locations where the birds were captured and follow their movements. Check the Ducks Unlimited website for maps of their satellite equipped and VHF transmittered birds.
Other partners that we would like to acknowledge for their assistance on these projects include the U.S. Fish and Wildlife Service (Chincoteague, Eastern Shore and Eastern Virginia Rivers National Wildlife Refuges); the Virginia Department of Conservation and Recreation; Jamestown Island/Colonial National Historic Park; and The Nature Conservancy, Virginia Coast Reserve.
Nesting Black Ducks
The Eastern Shore of Virginia may be more noted as a wintering area for black ducks, but Virginia is also on the southern edge of the black duck breeding range. Black Ducks nesting in Virginia are an important component of the total black duck population. But black ducks nesting in Virginia face some large obstacles. Land use changes, erosion of the Chesapeake Bay islands and marshes, and increases in predator communities have led to severe declines in the number of nesting black ducks.
The Chesapeake Bay islands and the barrier island complex off Virginia's Eastern Shore offer large blocks of habitat that could provide undisturbed nesting habitat for black ducks. However, factors such as predator populations (avian and mammalian) and other deficiencies of critical habitat components may be limiting breeding efforts. Aerial surveys and nest searches are conducted annually to monitor and index breeding waterfowl numbers, concentrations, and to inventory black duck breeding habitat in Virginia. VDGIF is also examining factors that affect recruitment rates of black ducks, such as breeding habitat selection, nest success, brood survival and effects of nest predation.