Long-term population trends of the Red-legged Cormorant Phalacrocorax gaimardi in the Argentine coast

MILLONES, A., GANDINI, P. & FRERE, E.

BIRD CONSERVATION INTERNATIONAL

CAMBRIDGE UNIV PRESS

Año: 2015 vol. 25 p. 234 - 241

0959-2709

The world population of Red-legged Cormorant Phalacrocorax gaimardi is reasonably smalland has showed rapid declines. In Argentina, this species breeds in 13 localities and is consideredas ?Endangered? by the national government. In this study, we provide information aboutpopulation trends of the Red-legged Cormorant on the Argentine coast, between 1990 and2009. We also discuss whether these trends could be related to sea surface temperature andmarine primary productivity, both of which are considered oceanographic factors that canaffect breeding seabirds. The long-term trend in the breeding population showed a slightdecrease of 1.2% per year. Seven colonies showed an average population change < 1. Periodsof stability and increase were identified over the study period, but they were insufficient tocompensate for the decreases. The largest colony of Red-legged Cormorants (La Mina, withmore than 55% of the entire breeding population) seems to determine the overall populationtrend. We did not find a direct relationship between the overall number of Red-legged Cormorantsand the two oceanographic factors analysed. However, our analysis detected a positive effectof ocean productivity close to the coast on the largest colony at the beginning of the breedingseason, suggesting that coastal ocean productivity could be an important factor affecting temporalvariations in the Argentinian population.