Breeding Status of Black-naped and Roseate Terns in the Yaeyama Islands, Ryukyu Islands, Japan, in 2001

Abstract

The distribution of breeding sites, number of nests, and timing of egg laying of the threatened Black-naped Tern Sterna sumatrana and Roseate Tern S. dougallii was surveyed across most of the Yaeyama Islands, located among the southern Ryukyu Islands, in the 2001 breeding season. Black-naped Terns bred in 42 sites that included 1-64 nests (average number of nests, 14.8±16.5 SD). Roseate Terns bred in six sites that included 1-123 nests (average number of nests, 59.8±57.3 SD). At most of the breeding sites, Black-naped Terns started to lay eggs in late June; while at some breeding sites, breeding commenced in early or mid July. Roseate Terns started to lay eggs in late June at two sites and in mid June at the other site.