Population status and trends of Southern Giant Petrels (Macronectes giganteus) breeding in north Patagonia, Argentina

The actual breeding population of the Southern Giant Petrel from the northern Patagonian colonies of Argentina on Isla Arce and Isla Gran Robredo was estimated to be 2,300 pairs. The available data sets are small, but showed a positive linear trend at Isla Gran Robredo over the last 14 years, but no trend was detected by a linear model at Isla Arce over a 17-year-period. Our study suggests higher population numbers in recent years. The close presence of increasing penguin, elephant seal and sea lion colonies, the low capture rates by longliners at the Patagonian shelf and/or the extensive use of waste from an increasing fleet of trawlers and jiggers as extra food supply might be some of the reasons for such a population increase.