Feeding Ecology of the Whiskered Tern, Chlidonias-Hybrida, in the Alligator Rivers Region, Northern-Territory

Prey from stomachs of 55 whiskered terns collected on a freshwater floodplain in the monsoonal Northern Territory were identified and counted. The terns ate a wide variety of invertebrate animals, most of them aquatic or with aquatic affinities. The most important prey in terms of dry weight were small fish, particularly Eleotridae, and insects, particularly Coleoptera, Odonata and Hemiptera. Vertebrates constituted 51% by dry weight of the diet. Numerically, dominant groups were Coleoptera, Odonata and small fish. Sexual differences were evident in morphology and diet. Males were heavier, had longer bills and wider gapes, and consumed more fish; females ate more invertebrates.