Estimates of Southern Rockhopper and Macaroni Penguin Numbers at the Ildefonso and Diego Ramírez Archipelagos, Chile, Using Quadrat and Distance-sampling Techniques

Abstract

Abstract Populations of Southern Rockhopper (Euduptes chrysocome chrysocome) and Macaroni (E. chrysolophus) Penguins at key breeding sites in the Southern Hemisphere have declined substantially in the past 50 years, but their statuses at important breeding sites in southern Chile are poorly known. In 2002, at two of the largest breeding sites in Chile, the Ildefonso and Diego Ramirez Archipelagos, we determined the number of breeding pairs. Based on nest density checks (quadrat and/or point-distance techniques) in a sample of habitats and calculations of the areas of occupied terrain, we estimated there were 86,400 (CL95%: 54,000 to 135,000) Rockhopper pairs and 5,660 (2,280 to 11,900) Macaroni pairs at Ildefonso, and 132,721 (88,860 to 185,665) Rockhopper pairs and about 15,600 Macaroni pairs at Diego Ramirez. Combined, the archipelagos hold about 28% of the world population of Southern Rockhopper Penguins.