SREL Reprint #1094




Effect of Diving Ducks on Benthic Food Resources during Winter in South Carolina


Loren M. Smith, Larry D. Vangilder, Richard T. Hoppe, Stephen J. Morreale and I. Lehr Brisbin, Jr.



Recently, increased attention has been focused on the role of the winter period in limiting waterfowl populations (Anderson & Batt 1983).  Many current studies suggest that winter food resources may be a limiting factor (Phersson 1976; Alexander & Hair 1979; Saylor & Afto 1981) for diving ducks.  Benthic food resources may decline over winter and competitive interactions among waterfowl, and between waterfowl and fish, have also been suggested as causes for food limitation (Nilsson 1969; Thompson 1973; Pehrsson 1976). Although recent studies have demonstrated that herbivorous waterfowl may reduce wetland macrophyte production (Smith & Odum 1981; Smith & Kadlec 1985) few studies have directly tested the hypothesis that diving ducks affect their winter invertebrate food resources.

Studies examining the impacts of diving ducks on benthic invertebrates have been complicated by the natural decline in invertebrates during winter and the difficulty of determining what portion of that decline, if any, may have been due to predation by waterfowl.  Also, many studies have indirectly extrapolated from estimated feeding rates to total food consumption.  In this study, our first objective was to estimate the direct impact of waterfowl predation on benthic invertebrates using enclosures.  Secondly, we investigated whether deep waters contained richer food resources, when compared with shallow waters.

SREL Reprint #1094

Smith, L.M., L.D. Vangilder, R.T. Hoppe, S.J. Morreale, and I.L. Brisbin Jr. 1986. Effect of diving ducks on benthic food resources during winter in South Carolina, USA. Wildfowl 37:136-141.

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