Comparative feeding ecology of Little Egrets on intertidal mudflats in Hong Kong, South China

The feeding ecology of Little Egrets (Egretta garzetta) in the Deep Bay Ram sar Site and Starling Inlet mudflats of Hong Kong was studied from October 1996 to October 1997. The feeding behavior of thirty birds on each mudflat was observed once a month and the densities of mudskippers (Boleophthalmus pectinirostris and Scartelaos viridis), crabs (Macrophthalmus sp. and Graps idae), nereid worms (Nereidae) and other benthic invertebrates were estimat ed. Birds in Deep Bay had a higher feeding rate, capture success and strike rate than those in Starling Inlet. Birds in Deep Bay mainly fed on benthic invertebrates, while those ill Starling Inlet fed on gobies (Mugilogobius piapensis) and shrimps Exopalamon styliferus). Nereid worms were only taken by birds in Deep Bay, even though the densities of nereid worms, mudskippe rs and crabs in Starling Inlet were higher. Although feeding behavior diffe red between the two mudflats, the estimated energy: intake rare was similar . Feeding on exposed mudflats alone cannot meet the Little Egrets' daily en ergetic requirements, but this habitat provides predictable food resources, such as nereid worms and gobies. The differences in feeding behavior were mainly due to differences in prey composition and behavior. Factors such as the hydrological regime and degree of organic enrichment may influence pre y availability for the birds and thus may indirectly contribute to the diff erences in behavior. We suggest that energy intake rate should be considere d when assessing the relative importance of habitats for wading birds.