THE FEEDING ECOLOGY OF MIGRATORY WADERS, PACIFIC GOLDEN PLOVERS (PLUVIALIS FULVA) AND WHIMBRELS (NUMENIUS PHAEOPUS VARIEGATUS) ON SOME INTERTIDAL FLATS IN SINGAPORE

Abstract

This thesis examines the feeding ecology of migratory waders on four intertidal flats in Singapore. At each site, the foraging activities of two species of waders, namely the Pacific Golden Plover (Pluvialis fulva (Gmelin)) and the Whimbrel (Numenius phaeopus variegatus (Scolpoli)) were studied. In order to determine the prey available to the waders, the invertebrate fauna at each site was surveyed. At Mandai Kechil, the main prey of both species of wader was the polychaete, Ceratonereis aequisetis Augener. Other prey taken at the intertidal mudflat were, swimming crabs, Portunus sp. and bivalves, which included the bag mussel, Musculista senhousia (Benson in Cantor, 1842). The Whimbrel was also observed to feed on the horseshoe crab, Carcinoscorpius rotundicauda Latreille. At Pasir Ris, the bag mussel was the predominant prey eaten by the waders. At the other sites, Changi and Kranji, the main prey of the waders were polychaetes, Tylonere is sp. and C. aequisetis respectively. Competition for food was observed at Changi where the density of prey was low. Both inter- and intra-specific competition were absent at Mandai Kechil and Pasir Ris. At the former, competition for polychaete prey was not seen as the density of the prey was relatively high. Furthermore, there was a partitioning of the food resource. The Pacific Golden Plovers and the Whimbrels fed on different sizes of polychaetes. At Pasir Ris, there was habitat partitioning as the waders fed on mussels on different parts of the mudflat. The greatest threat to the population of migratory waders in Singapore is the loss of the feeding sites through development and land reclamation.