Foods Of Ducks Wintering In Coastal South Carolina, 1965-1967

During the wintering seasons of 1965-1967, 706 waterfowl gizzards were collected and subsequent food habit studies were made. The collections represented 14 species of waterfowl (9 species of dabblers and 5 species of divers). Six hundred and five collections constituted the dabbling duck sample and 101 gizzards represented the diving duck sample. The most important foods consumed were from fresh and slightly brackish water habitats. Seeds of marsh plants and vegetative fragments and seeds of pondweeds were the primary foods consumed. Animal foods in the diet were not considered important. The most important food consumed by volume by dabbling ducks was Najas guadalupensis. The most important food consumed by volume by diving ducks was Brasenia schreberi. The plant most frequently used by dabblers was Scirpus validus, while the plant most frequently used by diving ducks was Brasenia schreberi. Food habit studies are of utmost importance in relating waterfowl utilization to various habitat types in aquatic ecosystems. They document the important food plants and animals and provide an understanding of the role of higher vertebrates within the trophic structure of the aquatic ecosystem (e. g. fresh water, estuarine, and marine). Although at times food habit studies are criticized, they are essential if we are to understand the functional processes of ecosystems. Previous studies of the food habits of waterfowl in South Carolina have been generally confined to local areas, or limited to a few analyses. Some of these studies are as follows. One hundred and fourteen duck stomachs from South Carolina were examined for the comprehensive report by Martin and Uhler (1939). An intensive study of 244 ducks, including 12 species, was conducted near Georgetown by Brock Conrad (1965). Twenty-five crops and 243 gizzards were examined and their contents were identified. McGilvrey (1966 a and b) published data concerning the fall food habits of dabbling ducks from Lake Marion and the area around Santee National Wildlife Refuge. Coastal South Carolina is extremely important for wintering waterfowl of the Atlantic Flyway. In the waterfowl survey of January 1968, South Carolina had 366,400 ducks, 15,800 gease, 100 brant, and 61,300 coots; they comprised 13.4 percent of the total population of wintering waterfowl in the Atlantic Flyway (Martinson et al., 1968). Comparable wintering populations occurred during the years of this study, 1965-1967. The objective of this study was to document the relative importance of foods for the major species of ducks utilizing the coastal, aquatic habitats of South Carolina. The resulting information could be used as a basis for studies having a more functional nature.

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