Long-term population increase of black-browed albatrosses <Emphasis Type="Italic">Thalassarche melanophrys</Emphasis> at Heard Island, 1947/1948 – 2000/2001

The breeding population of the black-browed albatross Thalassarche melanophrys has increased at Heard Island since the first census data were obtained in 1947/1948. Four breeding localities are known, and all populations have increased in the period 1947/1948-2000/2001. The breeding population is estimated to have been approximately 200 pairs in 1947/1948. Based on 2000/2001 census data, the population has increased to a minimum of approximately 600 pairs over the 53 years. Two mechanisms, that of increased prey availability through scavenging discards from trawlers operating within their foraging range, and climatic amelioration, are proposed as hypotheses for this increase.