Summary
Black-browed and grey-headed albatrosses breed at four known locations in Chile: Islas Diego de Almagro, Islote Evangelistas, Islas Ildefonso and Islas Diego Ramirez. Population sizes at these islands are vitally important to understanding the global conservation status of these species of albatrosses. During the incubation periods in 2001 and 2002 we determined population sizes using yacht-based photography (Diego de Almagro, Diego Ramirez), aerial photography (Evangelistas, Ildefonso, Diego Ramirez) and land-based photography and ground counts (Diego Ramirez). For black-browed albatrosses the censuses yielded 15,900 breeding pairs at Diego de Almagro, 4,670 pairs at Evangelistas, 47,000 pairs at Ildefonso and 55,000 pairs at Diego Ramirez. There were eight pairs of grey-headed albatrosses at Ildefonso and 16,400 pairs at Diego Ramirez. Totals for all islands combined were 123,000 pairs of black-browed albatrosses and 16,400 pairs of grey-headed albatrosses. Based on these estimates, and those in the published literature, Chile holds the second largest population (after the Falkland Islands/Islas Malvinas) of black-browed albatrosses in the world, representing about 20% of global numbers for the species. For grey-headed albatrosses, Chile also holds the second largest population in the world (after South Georgia), comprising about 20% of the breeding population for the species.