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To the Beauty of Birds

The Imperial Shag, Blue-eyed Shag, Blue-eyed Cormorant, King Shag Phalacrocorax atriceps, is a black and white cormorant native to many subantarctic islands, the Antarctic Peninsula and southern South America, primarily in rocky coastal regions, but locally also at large inland lakes. The taxonomy is very complex, and several subspecies are often considered separate species.

The taxonomy is very complex and species-limits within this group remain unresolved. The following are usually considered part of this group:

Imperial Shag, Phalacrocorax (atriceps) atriceps, from coastal southern Chile and Argentina.
King Cormorant/White-bellied Shag, Phalacrocorax (atriceps) albiventer,[NB 1] from the Falkland Islands, and locally in southern Argentina and Chile.
Antarctic Shag, Phalacrocorax (atriceps) bransfieldensis, from the Antarctic Peninsula and the South Shetland Islands.
South Georgia Shag, Phalacrocorax (atriceps) georgianus, from the South Georgia and the South Sandwich Islands, and South Orkney Islands.
Heard Shag, Phalacrocorax (atriceps) nivalis, from Heard Island.
Crozet Shag, Phalacrocorax (atriceps) melanogenis, from the Crozet and Prince Edward Islands.
Macquarie Shag, Phalacrocorax (atriceps) purpurascens, from Macquarie Island.
The subspecies vary primarily in the amount of white on the cheeks/ear-coverts, wing-coverts and back.

While some authorities accept all of the above – except albiventer – as separate species, others consider all as subspecies of a single species (a reasonable approach). With all this confusion it is no wonder I was also confused. Initially I thought the Imperial Shag and King Shag were different species in that the former had a prominent white streak on its back (photos # 9273,9275,9521, 9695) while the King Shag did not (all other photos). However, Burton and Croxall A Field Guide to the Wildlife of South Georgia suggest these differences are due to non-breeding and breeding plumage. Couve and Vidal in Birds of Patagonia, Tierra del Fuego & Antarctic Peninsula stated they were subspecies.

The Imperial Shag has a total length of 28–31 in with males averaging larger than females. It is endowed with glossy black feathers covering most of its body, with a white belly and neck. It possesses a distinctive ring of blue skin around its eyes, an orange-yellow nasal knob, pinkish legs and feet, and an erectile black crest. During the non-breeding season, adults lack the crest, have a duller facial area, and less/no white to the back/wings. It has a serrated bill used for catching fish.

Imperial Shag