A survey of ardeid nesting colonies in Hainan Province, China, was made between May and August 2004 and recorded 5,287 nests of four species (Little Egret Egretta garzetta, Cattle Egret Bubulcus ibis, Chinese Pond Heron Ardeola bacchus and Black-crowned Night Heron Nycticorax nycticorax), in 18 colonies in the northern area. Chinese Pond Heron was the dominant nesting species (62% of the total nests), while the Black-crowned Night Heron was the least abundant (4%). Numbers of the Chinese Pond Heron in Hainan is probably related to the presence of extensive ricefields in this area. Fewer numbers of nests of all species in the field were recorded compared with expected obtained from nest densities over a ricefield-dominated landscape in a previous study of ardeid nest abundance in central China. This suggests that nest density in central China could not be applied in Hainan and the assumption of 5 million nests in China requires further study. Based on available information for south China, numbers of nesting Cattle Egret and Chinese Pond Heron in Hainan (75% of total nests of each species), Black-crowned Night Heron in Guangdong and Guangxi, and Great Egret in Hong Kong (80%) are of regional importance. Using media to invite readers to report nesting colonies is recommended for similar surveys in a large area as it provides a cost effective approach to minimize sampling effort.