Brown skua, Stercorarius antarctica (also known as Catharacta antarctica), also known as the Antarctic, subantarctic, southern great or Falkland skua, photographed near Stromness, an abandoned whaling station on South Georgia Island, Antarctica.
Image: Alek O. Komarnitsky, 31 January 2009 [velociraptorize].
Question: This fierce but highly adaptable mystery bird has a very large range and a confusing taxonomy. Can you identify this species and tell me a little about it?
Response: This is a brown skua, Stercorarius antarctica, a predatory seabird that breeds in the sub-Antarctic and Antarctic zones and moves further north when not breeding. This bird employs a variety of methods to obtain food, including stealing from other birds (kleptoparasitism), scavenging on carcasses, and attacking and killing a wide variety of animal species, ranging from krill to birds.
Skua taxonomy is confusing and highly complex and is often disputed. Until recently, all the skuas of the world were thought to be just one species -- the Great Skua, Stercorarius skua, which is restricted to the Northern Hemisphere -- but now some experts think there may be as many as five separate skua species.
Adding strength to this view is the finding that on some southern islands, two forms will nest side by side without interbreeding, demonstrating that they are different species. However, adding to the confusion, this bird will hybridize with both the South Polar skua, Stercorarius maccormicki, and Chilean Skua, Stercorarius chilensis.
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