Seasonal Changes in Numbers and Diet of Kentish Plover Charadrius alexandrinus at Obitsu Estuary in Tokyo Bay

Abstract

From January 1975 to January 1977, we observed the feeding behavior of Kentish Plovers at the Obitsu estuary (35°24'N, 139°54'E) in Tokyo bay. This area is one of the most important staging sites for migratory shorebirdsin Honshu, and a valuable feeding site for the Kentish Plovers. During daytimeand at low tide, they spent an average of 86.4% of observation time for feeding. After mid December, their feeding rate increased and their resting rate decreased. Scopimera globosa, Nereidae and Capitellidae are the main prey of Kentish Plover here. Brachyura constituted 39.8-66.3% of the diet, but only 7.2-10.8% of the benthos, clearly showing that Kentish Plover positively selects Brachyura as prey.