Second North American Sea Duck Conference - Patuxent Wildlife ...

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SECOND NORTH AMERICAN SEA DUCK CONFERENCE WETLAND CHARACTERISTICS AND HABITAT USE BY WHITE-WINGED AND SURF SCOTERS IN THE MACKENZIE DELTA REGION Shannon Haszard¹ and Robert G. Clark² ¹Department of Biology, University of Saskatchewan; s_haszard@ducks.ca ²Canadian Wildlife Service and Department of Biology, University of Saskatchewan Reasons for apparent declines in populations of white-winged (Melanitta fusca) and surf scoters (Melanitta perspicillata) in the northern boreal forest are not well understood, but some evidence suggests factors associated with events on the breeding grounds may be responsible. Breeding ground changes could adversely affect upland or wetland habitats or key food sources for breeding females or ducklings, which in turn may lower productivity or recruitment. Like most boreal-nesting ducks, virtually nothing is known about wetland habitat preferences of scoters. Determining habitat features that scoters need to breed successfully, and how habitat changes in the boreal forest affect scoters, is an important step in understanding their ecology and developing conservation initiatives. Thus, my overall goal was to look for evidence of habitat selection in scoters by characterizing features of wetlands used by scoter pairs and broods, and comparing these features with those of areas not used by scoters. Habitat characteristics and scoter use of wetlands in recently burned forest was also contrasted with unburned forest to determine whether habitat change caused by fire could affect patterns of habitat use by scoters. Scoter pairs and broods used wetlands with more abundant food, a finding that is consistent with many other waterfowl studies. However, unlike some previous waterfowl studies, I did not find a consistent correlation between total phosphorus levels and amphipod abundance or wetland use by scoters. I did not detect a difference in fine-scale features of wetlands surrounded by burned versus unburned vegetation. This study of scoters in the northern boreal forest was among the first to determine why scoters use specific wetlands or areas and not others. 90 ANNAPOLIS, MARYLAND, USA NOV. 7-11, 2005
David Kidwell and Matthew C. Perry SECOND NORTH AMERICAN SEA DUCK CONFERENCE DELINEATION OF SURF SCOTER HABITAT IN CHESAPEAKE BAY, MARYLAND: MACROBENTHIC AND SEDIMENT COMPOSITION OF SURF SCOTER FEEDING SITES USGS Patuxent Wildlife Research Center, Laurel, MD 20708 USA; dkidwell@usgs.gov Surveys of surf scoters (Melanitta perspicillata) along the Atlantic coast of the United States have shown population declines in recent decades. The Chesapeake Bay has traditionally been a key wintering area for surf scoters. Past and present research has shown that bivalves constitute a major food item for seaducks in the Chesapeake Bay, with surf scoters feeding primarily on hooked mussel (Ischadium recurvum) and dwarf surf clam (Mulinia lateralis). Degraded water quality conditions in the Chesapeake Bay have been well documented and have been shown to greatly influence the composition of benthic communities. Large concentrations of feeding surf scoters (>500 individuals) in the Bay were determined through monthly boat surveys. Locations consistently lacking surf scoters were also determined. Macrobenthos were seasonally sampled at 3 locations containing scoters and 3 locations without scoters. A 1 kilometer square grid was superimposed over each location using GIS and sampling sites within the square were randomly chosen. Benthos were sampled at each site using SCUBA and a meter square quadrat. Biomass and size class estimates were determined for all bivalves within each kilometer square. Results indicated that scoter feeding sites contained significantly greater biomass of M. lateralis, I. recurvum, and Gemma gemma than locations where no scoters were present. Substrate differences were also detected, with scoter feeding sites being composed of a sand/shell mix while non-scoter sites consisted primarily of mud. This data indicates that surf scoters in the Chesapeake Bay are selecting areas with high densities of preferred food items, potentially maximizing there foraging energetics. In addition, two scoter feeding sites also contained a patchwork of eastern oyster (Crassostrea virginica) and oyster shell, on which much of the I. recurvum was attached. This suggests the possibility that surf scoters utilize eastern oyster habitat and the dramatic depletion of oysters in the Bay could be a possible factor in surf scoter decline. More research is needed into the possible relationship between surf scoters and the eastern oyster. NOV. 7-11, 2005 ANNAPOLIS, MARYLAND, USA 91
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