New Breeding Localities of the Bridled Tern Sterna anaethetus and its Measurements

Abstract

The first breeding record in Japan of Bridled Tern Sterna anaethetus is reported from Nakanokami-shima, Okinawa prefecture, South Ryukyus (Abe and Mano 1980). In this paper, we report two other breeding localities of the species. One is Fude Rock where we have already suggested its breeding. The survey of this area was made on 27 and 28 June 1981. Fude Rock is a small rocky islet situated 12km NE of Seto-zaki, Miyako-jima, Okinawa prefecture, having an area of 140m×70m and the altitude, 9m. There is a lighthouse on the islet. Sterna anaethetus, Sterna sumatrana, Anous stolidus and Sula leucogaster settled on Fude Rock and adjacent tiny rocks. About sixty Bridled Terns were breeding, and some of them were in incubation. Another breeding locality is "Panari" commonly called, "Gunkan-jima", is situated near the southeastern end of Miyako-jima. We visited this area on 9 July 1981. The area is a small ring-shaped coral reef, and there are many small rocks at the eastern side of the area. Sterna anaethetus, Sterna sumatrana and Anous stolidus were observed on these rocks. About one hundred or one hundred and fifty Bridled Terns were counted, and their eggs and early chicks were found. The measurements of the Bridled Terns captured on Nakanokami-shima are given.