By Tina Yerkes, Ph.D.
The American black duck, considered by many in the Atlantic Flyway to be the king of all ducks, is prized by coastal hunters. Black ducks were once the predominant species harvested by Atlantic Flyway waterfowlers. Unfortunately, wintering black duck numbers have declined by as much as 60 percent. One of several possible explanations for this decline is the loss and degradation of coastal habitat where the birds winter. Coastal salt marshes are the most threatened wetland systems in North America.
Oddly enough, despite higher historic wetland losses and extensive development, wintering numbers of black ducks have stabilized in the northern part of the Atlantic Flyway. But south of New Jersey, where wetland losses have been less severe, wintering numbers continue to decline.
Can remaining habitat support the current wintering population of black ducks? And how much more coastal wetland habitat needs to be restored and protected to support the North American Waterfowl Management Plan’s (NAWMP) population goal for black ducks? These are the primary questions DU and its partners have set out to address through recent research projects.
Wintering habitat limitation on duck populations is rare. Most ducks survive the winter relatively well. But if this limitation is going to occur, it will likely be found in the Atlantic Flyway, where extensive wetland losses and intense development have degraded salt marsh habitats and introduced human disturbance.
During the winter and spring, food is very important to ducks for survival and preparation for the upcoming breeding season. To understand the food resources currently available to wintering black ducks and to adapt habitat programs to “fill in the gaps” along the Atlantic Flyway, Ducks Unlimited and multiple partners recently completed a study on Long Island, New York. This study has been extended to additional sites in Virginia and New Jersey.
To learn more about black duck habitat use and food resources, researchers trapped 30 hens and fitted them with radio transmitters during the winters of 2004-2005 and 2005-2006. The transmitters allowed researchers to determine overall movements as well as habitat use and behavioral activity while the birds were in different habitat types. Researchers also conducted extensive sampling of invertebrates and seeds in wetland habitats used by black ducks to determine the type and amount of food available for the birds. The same type of study will be done in Virginia and New Jersey so that biologists can compare “apples to apples” on a flyway-wide scale and determine habitat restoration or protection needs throughout the flyway.