A bird survey of Iriomote I., Yaeyama Group, S. Ryu Kyus

Abstract

1. As an expedition member of Yokkaichi Minami High School to the Yaeyama Group, S. Ryu Kyus, the author investigated birds on Iriomote I. and the adjacent Nakano-Kamijima.2. Thirty eight species of 23 Families including 7 species new to the islands, were recorded of which 32 species were common to Japan and 37 to Formosa. Nineteen species were common to Japan and 21 to Formosa as subspecies.3. The islands are of special interest as an intergrading area between oriental and palearctic zones and among observed species, the following were interesting zoogeographically and ecologically: Passer montanus (new record), Lanius cristatue lucionensis (on migration), Hirundo tahitica, Sula dactylatra, Thalasseus bergii, Streptopelia orientalis stimpsoni and Sterna sumatrana. The latter two species breed on a small rocky island and Streptopelia were breeding colonially in high density at a grassy place (not on the) and flew over the sea to the feeding place on the oposite coast.4. On Nakano-Kamijima, there was a mixed sea-bird colony consisting of Anous stolidus, sterna fuscata, Calonectris leucomelas (possibly the southern limit), and Sula leucogaster, with the total of some 20, 000 individuals. There habitat segregation especially between Sterna and Anous was demarcated.5. On this island sea-bird eggs are being taken in great numbers and the protection from this is considered to be urgently needed.