Wandering Albatrosses Diomedea exulans are globally threatened due to population declines and the Macquarie Island breeding populations is particularly vulnerable as it comprises fewer than 20 breeding pairs. Most breeding birds in this small population are banded and monitoring over the last 40 years has increasingly focused on their conservation status. Demographic trends of the Macquarie Island Wandering Albatrosses between 1955 and 2003 are described here, combining historical data with information from an intensive demographic study conducted between 1994 and 2003. Annual breeding effort and survival varied markedly with breeding numbers declining from a peak in 1964 to near extinction levels in the mid 1980’s. Underlying this decline was a significant decrease in juvenile survival and, to a lesser extent, adult survival. These survival changes were coincident with changes in fishing effort in the eastern Indian Ocean. Breeding numbers slowly increased on Macquarie Island through the 1980s, reaching 19 breeding pairs in the mid 1990s and the population remains at this level today. Trends in population numbers and survival are similar to that observed in other populations in the Indian Ocean including Marion Island, Iles Crozet and Amsterdam Island. The age distribution of the current breeding population also provides supporting evidence that there were periods of low juvenile survival. Although the current population has remained stable at approximately 19 breeding pairs for the last seven years, the small size makes it extremely vulnerable to any activities that elevate mortality rates.
Número de documento:
Punto(s) de la agenda