HABITAT USE BY SYMPATRIC FEMALE MALLARDS AND AMERICAN BLACK DUCKS BREEDING IN A FORESTED ENVIRONMENT

There has been much speculation regarding whether breeding mallards (A nas platyrhynchos) and American black ducks (A. rubripes) use similar habitat types in forested areas, which could lead to increased intersp ecific contact. To study this issue, we used radiotelemetry during 199 0-1991 on sympatric female mallards and black ducks breeding in the we stern Adirondack Mountains of New York. Mallard and black duck pairs o ccupied the general area at a density of 0.7 and 0.6/km(2), respective ly. Black duck home ranges tended to be larger than those of mallards, although the difference was not significant. Habitat composition with in the home ranges of mallards and black ducks was similar, upland for est being the dominant habitat type, followed by wetlands, disturbed a reas, and active residential sites. Within home ranges, mallards and b lack ducks were similar in their use of four major wetland habitat typ es. Our data suggest that undisturbed forest and habitat use within su ch areas may not serve as an isolating mechanism between breeding mall ards and black ducks.