Decrease in Numbers of the Eastern Rockhopper PenguinEudyptes Chrysocome Filholiat Marion Island, 1994/95–2002/03

Pelagic predators

“…The decrease in the population of Rockhopper Penguins has been even more marked at Marion Island, falling by c. 40% in 14 years (Crawford et al 2003b). Most of the decrease occurred in the late 1990s, with the breeding population decreasing by an average of 12% per year from 1994/95 to 2001/02 (Crawford et al 2003b). The population at Prince Edward Island has apparently remained stable over the last two decades , although the accuracy of the previous estimate from Prince Edward Island is unknown.…”

“…Macaroni Penguins are less constrained by a need for sheltered landing sites, breeding in more than 50 colonies at Marion Island and seven at Prince Edward Island, but some 80% breed at two sites on the east coast of Marion Island, at Bullard and Kildalkey (Crawford et al 2003c;Ryan et al 2003a), where they have removed some 3 x 10 5 m 3 of peat (Hall & Williams 1981). By comparison, more agile Rockhopper Penguins occur around the coasts of both islands, breeding along all but the most sheer of cliffs (Crawford et al 2003b;Ryan et al 2003a). They also penetrate further inland, at least locally, but do not venture as far from the coast as the small numbers of Gentoo Penguins breeding at both islands (Adams & Wilson 1987;Crawford et al 2003d;Ryan et al 2003a).…”

“…The islands support some 13% of King Penguins worldwide, 4% of Macaroni Penguins and only 0.5% of Gentoo Penguins (Woehler 1993;Williams 1995;Crawford & Cooper 2003). The population of Southern Rockhopper Penguins is about 5% of the world population (and 17% of the eastern race filholi), but this is affected by the rapid decreases observed at many colonies, including Marion Island (Crawford et al 2003b;BirdLife International 2004a). Penguins dominate the avian biomass at the islands, comprising some 97% of the biomass of breeding adults at Marion Island (9 200 tons) and 60% of the biomass at Prince Edward Island (750 tons).…”

“…Nel et al 2002c;Crawford et al 2003aCrawford et al , 2003bCrawford et al , 2003cCrawford et al , 2003d. Demographic parameters are estimated from individually-marked birds in several study colonies that have been followed since the early 1980s (Nel et al 2002c).…”

“…Breeding success has increased over the last decade, but appears to have been too low to maintain a stable population (Crawford et al 2003c). The decrease in the population of Rockhopper Penguins has been even more marked at Marion Island, falling by c. 40% in 14 years (Crawford et al 2003b). Most of the decrease occurred in the late 1990s, with the breeding population decreasing by an average of 12% per year from 1994/95 to 2001/02 (Crawford et al 2003b).…”