The Japanese White-eye, Zosterops japonica, are known as a nectar robber from several kinds of introduced flowers (Ueda & Nagano 1991, Ueda & Karaki 1997). Hibiscus flowers, pierced by white-eyes for nectar robbing, were surveyed at 49 locations in 21 southern islands belonging to Izu, Bonin, Osumi, Tokara, Amami, Ryukyu, Daito, Miyako, Yaeyama Islands, and Formosa, from 1991 to 1998. Out of 6413 flowers checked, 1947 (30.4%) had holes and slits in the bottom of the flowers, having been pierced by white-eyes.Nectar robbing did not occur in northern islands located higher than 290 N in latitude.
The nectar robbing behaviour was restricted to the population inhabiting the sub-tropical islands; however, it was not observed on the Yaeyama Islands and Minami-daito-jima (Daito Islands). Such robbing behaviour was not observed between native plants on any of the islands.