Food Habits of Three Bird Species on Phosphatemine Settling Ponds and Natural Wetlands

Common moorhens (Gallinula chloropus), double-crested cormorants (Phalacrocorax auritus), and mottled ducks (Anas julvigula) were collected from phosphate-mine settling ponds and natural wetlands in north and central Florida between June and October 1981. Contents of esophagi, proventriculi, and stomachs were removed from 185 birds, identified, and measured by volumetric displacement. Aggregate percentages of food items in diets were compared between settling ponds and natural wetlands. Rank order of items in moorhen diets differed among the 2 habitats. Plant foods comprised at least 80% of moorhen diets on both habitats. Cormorants primarily consumed the same species of fish on settling ponds and natural areas. However, high numbers of mosquito fish (Gambusia afjinis) and small invertebrates were consumed on the settling ponds but not on the natural wetlands. Mottled duck diets from settling ponds and natural wetlands in central Florida were not positively correlated based on rankings of food items. A diversity of both plant and animal species were consumed by these ducks. Mottled duck diets included 27% animal matter on settling ponds and 50% animal matter on natural wetlands.

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