Population of Waterbirds in the Breeding Colony at Khuan Khi Sian, Thailand’s First Ramsar Site

This study investigated the species composition, population sizeand population fluctuation of waterbirds in Melaleuca swamp forest atKhuan Khi Sian, Thale Noi Non-hunting Area, Phatthalung Province,southern Thailand. The study was conducted from April 1998 to March1999. The number of waterbirds was counted monthly and some environmentalfactors were also observed. It was found that the Melaleucaswamp forest was a breeding site of five species of waterbirds, consisting ofPhalacrocorax niger, Ardea purpurea, Bubulcus ibis, Egretta garzetta andNycticorax nycticorax. This area was also served as a night roosting site for arare migratory species, Threskiornis melanocephalus from April to July. Thepopulation density of waterbirds in the breeding colony greatly fluctuatedthroughout the year, but peaked in May when the number reached 20,430individuals. The lowest number was 136 in September. Of all the waterbirds,only P. niger and A. purpurea used this breeding area throughout the year.Considering environmental factors, the number of B. ibis, N. nycticorax andT. melanocephalus showed correlations with mean temperature, relativehumidity and total rainfall.