Effect of diving ducks on benthic food resources during winter in South Carolina, U.S.A

Abstract

The effect of diving duck predation on benthic macroinvertebrate numbers and biomass was investigated with the use of exclosures, during winter 1983-84, in a South Carolina reservoir. The relationship of food quality with increasing water depth was also studied. The most numerous waterfowl species occurring that feed on benthic invertebrates were Lesser Scaup Aythya affinis, Ring-necked Duck A. collaris, Bufflehead Bucephala albeola, and ruddy Duck Oxyura jamaicensis. Birds reached peak numbers in early January, and departed in late March. Waterfowl had little overall impact on benthic macroinvertebrate biomass and numbers during winter except for clams (Corbiculidae). For most invertebrate taxa, deeper waters did not contain richer food supplies when compared with shallow waters. A hypothesized relationship of food quality and water depth may not play an important role in the habitat segregation of male and female diving ducks.