Factors affecting the breeding success of south polar skua

Among marine organisms breeding in Antarctica, the South Polar skua (Catharacta maccormicki) combines the traits of the species more exposed to the bioaccumulation of persistent contaminants. Skuas are opportunistic top predators, and during the breeding season in Antarctica they adopt a wide range of feeding tactics that enable them to prey or scavenge on all profitable marine or terrestrial food resources according to their temporal and spatial availability. Many skuas nest close to penguin rookeries, and Adélie penguins are an important component of their diet. However, in areas such as the Larsemann Hills (Princess Elizabeth Land) where there are no breeding penguins, the snow petrel (Pagodroma nivea), together with other seabirds, various marine foods and refuse (meat, fish and vegetable remains) from nearby stations, becomes the major dietary component of skuas. South Polar skuas have one of the longest migration flights of any bird, and they can range over huge areas of the ocean up to the north Atlantic and Greenland during the Antarctic winter. Their feeding behaviour in Antarctica and especially that in more polluted marine ecosystems of the Northern Hemisphere exposes South Polar skuas to enhanced uptake of persistent contaminants. Early biomonitoring surveys of Antarctic wildlife identified the South Polar skua and brown skua (C. lonnbergi) as the species with the highest concentrations of persistent contaminants.