Observations on the status of the Short-tailed Albatross Diomedea albatrus on Torishima in 1977/78 and 1978/79

Abstract

1. Current breeding status of the endangered Short-tailed Albatross Dimedea albatrus, was reported based on two visits a year, i. e. egg and chick seasons, to Torishima, the southern Izu Shoto, on which the only known breeding station for this species exists.
2. In the 1977/78 season, 73 adults were observed at the beginning of the season, and at least 12 chicks, but not larger than 20, seemed to be reared. In 1978/79, 80 adults at the beginning, 95 in the chick season, were observed and 22 chicks were reared.
3. Although recent counts of adults indicate steady albeit very slow increase in numbers and perhaps 50-60 pairs are actually breeding currently, the production of young has been smaller than expected.
4. Comparative breeding data in the early 1960's and of recent seasons suggest that the nesting success is low recently, particularly at the east part of the breeding colony, where vegetation has become stunted in the last two decades. It was suggested that this change in vegetation might be a factor contributing to observed low breeding output.
5. In March 1979, an expedition party rediscovered 16 Short-tailed Albatrosses on Minamikojima in the Senkaku Retto, the southwestern Ryukyus, although breeding was not confirmed. From these observations the total world population was roughly estimated to amount to well over 150 and perhaps in short reach of 200.
6. Protection measures effective at the breeding ground were proposed and the status of the Black-footed Albatross nesting on Torishima was also reported in brief.