Responses of Pygoscelis adeliae and P. papua populations to environmental changes at Isla 25 de Mayo (King George Island)

Abstract

As part of a monitoring study of Ade ´lie and Gentoo penguin colonies, birds occupying nests with eggs and chicks in cre `ches were counted annually from the 1995/1996 to the 2006/2007 seasons at Stranger Point, Isla 25 de Mayo (King George Island), Antarctica. During the study period the Ade ´lie penguin population showed a decrease of 62%. The number of chicks in cre `ches followed a similar trend, the smallest number occurring in 2002, when it was 63% lower than in 1995/1996. In contrast, the Gentoo breeding population size increased by 68%, while chicks produced increased by 63%. Despite the opposing trends in population size between species, there was a positive relation in their interannual variation, although the extent, and for some years the direction, of the change observed always favoured Gentoo penguins. Breeding success (chicks in cre `ches/nests with eggs) fluctuated between 0.65 and 1.26 for Ade ´lies and between 0.76 and 1.27 for Gentoo penguins, and did not differ significantly between species. The similar breeding success of these species suggests that the contrasting population trends observed were driven by factors operating over winter. We suggest that current changes in environmental conditions may affect adult birds of both species during the previous winter with different intensity but in a roughly similar way, but that juvenile survival of both species and thus the recruitment of new breeders might be affected differentially, with a much lower survival rate of juvenile Ade ´lie penguins.

Antarctic Futures

“…Results obtained in several studies support this (Carlini et al 2009;Hinke et al 2007;. Results obtained in several studies support this (Carlini et al 2009;Hinke et al 2007;.…”

Abundance and breeding distribution of seabirds in the northern part of the Danco Coast, Antarctic Peninsula

“…For this reason, arbitrarily and applying a more conservative approach, we only discuss here those species for which annual population growth rate (l) was below 0.97 or above 1.03. Population trends of pygoscelids penguins in the Antarctic Peninsula and associated islands have been studied by numerous authors (Woehler & Croxall 1997;Hinke et al 2007;Sander, Balbao, Polito et al 2007;Carlini et al 2009;Trivelpiece et al 2011;Lynch, Ron et al 2012;Lynch, William et al 2012; among many others). The contrasting trends between species are of particular interest because as top predators, they integrate and/or magnify changes in the lower levels of the food chain.…”

Introduction to the special issue on the Life in Antarctica: Boundaries and Gradients in a Changing Environment (XIth SCAR Biology Symposium)

“…For instance, a decline of some species of penguins, as the chinstrap penguin (Pygoscelis antarctica) and the Adélie penguin (P. adeliae), have been reported in the Antarctic Peninsula (Carlini et al 2009;Trivelpiece et al 2011;Barbosa et al 2012), while in the Ross Sea, the Adélie penguin has increased or decreased in numbers depending of the sea-ice trends (Smith et al 1999;Ainley et al 2010).…”