Abstract
The present breeding status of the endangered Short-tailed Albatross Diomedea albatrus, on Torishima, the Izu Is. was investigated. In the 1979/80 season, more than 50 eggs were laid and 20 young fledged. In 1980/81, 54 eggs laid and 32 fledged. Breeding success was similar to that in the early 1960s. About 130 adults and sub-adults were observed. The population is still increasing. The rats Rattus rattus, inhabiting much of Torishima were very numerous in 1979/80 but seemed to be decreasing in 1980/81. Although the rats are present on the albatross' nesting grounds in appreciable numbers, the species is primarily a herbivor and might be less harmful to the eggs and hatchlings than previously supposed. Recent observations on the status of the Short-tailed Albatross on Torishima, the Senkaku Is., and Hawaiian Is. suggest that the world population is at least 250 individuals.
