Population dynamics of Black-browed and Grey-headed Albatrosses were studied at Bird Island, South Georgia for 17 consecutive years (1975-1991). Over this period almost all the Grey-headed Albatross colonies decreased, at an average rate of 1.8% per annum. Although the total Black-browed Albatross population increased (at 0.8% pa.), 14 of the 23 colonies (including both study colonies) decreased. Black-browed Albatrosses follow an annual breeding cycle, with over 80% of birds successful in rearing a chick and 75% of those failing to do so returning to breed the next year, 5-10% of both categories delaying one further year (even when still paired). Grey-headed Albatrosses are essentially biennial,
