The status of the black-browed and grey-headed albatrosses on Macquarie Island

Abstract

Marginal populations of both black-browed (Diomedea melanophris) and grey-headed (D, chrysostoma) albatrosses breed in the Macquarie Island Nature Reserve. Black-browed albatrosses breed in three colonies: one, on North Head, has been declining in numbers since the 1950's; the second, in the southwest corner of the island, has been increasing; the third, on Bishop and Clerk Islets, appears to be larger than the second. Breeding success has been high in the southwest colony over the past ten years, but recruitment of banded youngsters into the breeding population has been very low. Grey-headed albatrosses, biennial breeders, breed only in the southwest corner of the island, with an apparently stable breeding population. The breeding success is slightly higher than that of the black-browed albatrosses but again recruitment into the breeding population is very low. First breeding records of birds banded as fledglings are given for both species and these data are used to extrapolate minimum ages for birds banded as adults in the 1950's. Observations from several seasons are combined to construct the breeding cycles of both species at Macquarie Island Nature Reserve