ANNUAL VARIATION IN SURVIVAL AND RETURN RATE IN BREEDING ADELIE

JUÁRES MA, LIBERTELLI MM, SANTOS MM, CORIA NR, NEGRETE J, DONINI G, MUT COLL S, MATUS F, CARLINI AR.

Conferencia; XXXI SCAR Open Science Conference; 2010

In Antarctic ecosystems, environmental conditions have shown to affect population?sdynamics of seabirds. Among these, populations of Adélie penguin Pygoscelis adeliae are especially sensitive to climate variations, since they are closely associated with sea ice conditions. The increment of sea surface temperatures during winter causes the reduction of sea ice extent, affecting the abundance and distribution of Antarctic krill, principal prey of this species. In this study we analyze the annual variation in survival and return rate in breeding Adélie penguins ringed during breeding seasons 1995/96-2004/05 at Laurie Island, South Orkney Islands. For this purpose we used presence/absence data of marked birds in previous years, excluding 2000/01 season where data were not available. Overall survival and return rates average 61.64% and 54.36% respectively. Survival and return rate reach maximum values (87 and 86% respectively) during the 1998/99 season while minimum values (28 and 25% respectively) were recorded during 1999/2000 season. A similar trend was observed for interannual variation in the breeding population size, with an increase of 11.4% in the population size for 1998/99 followed by a decrease of 42.7% in the next season. Survival and return rates were closely associated to winter availability of its main prey since high and low values of krill biomass around South Orkneys islands were recorded in 1998/99 and 1999/2000 seasons respectively.Pygoscelis adeliae are especially sensitive to climate variations, since they are closely associated with sea ice conditions. The increment of sea surface temperatures during winter causes the reduction of sea ice extent, affecting the abundance and distribution of Antarctic krill, principal prey of this species. In this study we analyze the annual variation in survival and return rate in breeding Adélie penguins ringed during breeding seasons 1995/96-2004/05 at Laurie Island, South Orkney Islands. For this purpose we used presence/absence data of marked birds in previous years, excluding 2000/01 season where data were not available. Overall survivaland return rates average 61.64% and 54.36% respectively. Survival and return rate reach maximum values (87 and 86% respectively) during the 1998/99 season while minimum values (28 and 25% respectively) were recorded during 1999/2000 season. A similar trend was observed for interannual variation in the breeding population size, with an increase of 11.4% in the population size for 1998/99 followed by a decrease of 42.7% in the next season. Survival and return rates were closely associated to winter availability of its main prey since high and low values of krill biomass around South Orkneys islands were recorded in 1998/99 and 1999/2000 seasons respectively.