The Antarctic Shag is also known as the Imperial Cormorant, the King Cormorant, the Imperial Shag, the Blue-eyed Shag or the Antarctic Cormorant. There is often confusion around the names cormorant and shag, but they are simply different names for the same bird. Some consider all of the above to be sub-species of a single species of cormorant, while others view them all as a single species – the jury is still out!
Antarctic Shags are 72 cm (28 inches) in length, with a wingspan of 124 cm (49 inches). They have white lower parts and black upper parts, with a black tail and a white bar on the wings. The distinctive blue ring around the eye is most prominent during the breeding season. There is an orange growth, or caruncle at the base of the beak.
The Antarctic Shag is the only member of the cormorant family to be found in Antarctica proper. They forage on open water in flocks, and will swim and dive in sync. Their food is mainly fish, but they will also feed on crustaceans, squid and other invertebrates.
The Antarctic Cormorant breeds on the Antarctic Peninsula, the South Shetland Islands and Elephant Island. They nest in colonies, which are usually small, but may number hundreds of pairs and can include other sea birds. Antarctic Shags are monogamous, and each season a pair produces up to 5 eggs, which are hatched in about 5 weeks. There are heavy losses of chicks and eggs to predation by skuas and sheathbills. Both parents brood the chicks until they fledge at around 7 weeks of age. The fledglings then gather in flocks.
The IUCN classes Antarctic Shags as Least Concern, although small populations and limited ranges mean that these birds are vulnerable to the negative impacts of pollution and climate change. There is a potential threat from introduced predators such as cats and rats.