Activity Patterns of Dabbling Ducks Wintering in Coastal South Carolina

Nearctic dabbling ducks (Anatini) use varied wintering habitats. Spatial and structural variability among these may translate into differing capabilities of habitats to meet behavioral and physiological requirements of ducks. Our study was conducted on the Santee River Delta (SRD) in South Carolina, an important wintering area for dabbling ducks in the Atlantic Flyway. Our objectives were to determine (1) activities of dabbling ducks wintering on the SRD, (2) if different habitats within managed wetlands had differing functional values (intra-and interspecific), based on dabbling duck behavioral usage, and (3) if there were intraspecific differences in activity patterns between those observed in this study and those reported for other continental wintering locations. We quantified activities of northern pintail (Anas acuta), American green-winged teal (A. crecca carolinensis), American wigeon (A. americana), gadwall (A. strepera), northern shoveler, (A. clypeatd), mallard (A.platyrhynchos), and blue-winged teal (A. discors) by sex and habitat type. Frequency of activities differed (P < 0.001) between male and female pintail, green-winged teal, shoveler, and mallard in some habitats, but did not differ (0.06 < P < 0.90) between male and female wigeon, gadwall, and blue-winged teal in any habitats. Although activity patterns were similar among certain species, the frequency of occurrence of activities generally differed (P < 0.05) among habitats within species and among species within habitats. Frequency of occurrence of feeding, resting, and swimming differed (P < 0.05) most among species, whereas comfort, alert, and courtship activities differed least. Pintail, mallard, gadwall, blue-winged teal, and greenwinged teal spent substantially more diurnal time feeding in the SRD than in any other wintering area previously studied. We hypothesize that greater feeding frequency in the SRD may be explained by ambient temperatures below lower critical temperatures and by reliance on natural foods with lower metabolizable energy than agricultural seeds. We recommend against the introduction of agricultural foods to the SRD as a management option; rather, we believe that current management practices in the SRD will continue to provide important habitat for a wintering dabbling ducks and other wildlife.

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