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At least 1,117 records · Page 62Linked to original sources
USGS1982

Food habits of diving ducks in the Carolinas

Food habits analyses were conducted on 264 diving ducks (7 species) from North and South Carolina during the 1970'S. The Baltic clam (Macoma balthica) was the predominant food among canvasbacks (Aythya valisineria) from the Pamlico River area, whereas sago pondweed (Potamogeton pectinatus) predominated in birds from impoundments in North and South Carolina. Shoalgrass (Halodule beaudettei) formed 100% of the gullet food and 99% of the gizzard food in redheads (Aythya americana) from Pamlico Sound. Lesser scaup (Aythya affinis) in North Carolina had fed predominantly on mollusks (Mulinia lateralis and Rangia cuneata), whereas widgeon grass (Ruppia maritima) was the predominant food in birds from South Carolina. In North Carolina, ring-necked ducks (Aythya collaris) fed mainly on vegetation, and greater scaup (Aythya marila), bufflehead (Bucephala albeola), and ruddy ducks (Oxyura jamaicensis) fed mainly on Mulinia lateralis. Food habits data from this study when compared with historical food habits of these species indicate that most diving duck species were feeding more on invertebrates and less on submerged aquatic vegetation than in the past. North and South Carolina have a diverse food supply and appear to offer waterfowl adequate wintering habitat based on these food habits studies. Present trends in wintering habitat, however, could adversely affect diving duck populations in the future.

Proceedings of the Annual Conference of the Southe↗
USGS1997

Evaluation of a mallard HSI model for the Lower Mississippi Valley

We evaluated a habitat suitability (HSI) model developed for mallards ( Anas platyrhynchos ) wintering in the Lower Mississippi Valley by comparing mallard densities obtained from aerial surveys with habitat suitability indices derived from satellite imagery for 25, 256km 2 sampling units. Regression models that related mallard densities to habitat suitability indices accounted for only 29% of the variability in the data and the 95% confidence interval of predicted mallard densities included zero for most habitat suitability indices evaluated. Thus, we conclude that the published HSI model is a poor predictor of wintering mallard density in the Lower Mississippi Valley. We suggest model revision to allow users to remotely obtain model inputs for habitat characteristics at landscape scales. Further, we suggest the model be revised to consider yearly variation in habitat and flood conditions that better reflect the ability of an area to support wintering mallards.

Arkansas, Louisiana, Mississippi↗