8. Food preferences of the common tern, <i>sterna hirundo</i> (Linnaeus, 1758) at the Densu floodplains, Accra

Abstract

Seabirds are important in the dynamics of marine ecosystems because they recycle important biomass of lower trophic level organisms. Their faeces and carcasses provide important food sources for terrestrial and benthic scavengers. As a result of the abundance of food resources along the coast of Ghana, common terns (Sterna hirundo) are found in large numbers in productive brackish or saltwater wetlands, and are notable for indicating location of rich fish stocks at sea and in lagoons. The study aimed to determine the variety of food available, and any food preferences exhibited by S. hirundo at the Densu floodplains near Accra. While earlier studies of food habits of seabirds worldwide used examination of regurgitates and telescopic observations, the study quantitatively analyzed guts of common tern for their food content using standardized methods. The utilization by common terns of the Panbros lagoon fish resource during roosting in the night was quantified. Results showed that food available to the birds included marine and fresh or brackish water fish, crustaceans and worms. During caging, only one bird fed on 15 individuals of Hemichromis fasciatus. Prey items such as exoskeleton of crab zoea larvae, capitellid worms, fish otolith, pieces of fish bones and vertebrae, detrital materials and sand grains were found in the guts. The presence of capitellid worms in the guts, a known indicator of excess nutrient enrichment, showed that S. hirundo utilized the Panbros lagoon fish resource in feeding, and the roosting ground was under much stress. The study stressed the importance of complementing conservation efforts for common terns with attempts to manage the fish resources in the Densu floodplains.