South Polar Skua  |  

The south polar skua (Stercorarius maccormicki) is a large seabird in the skua family, Stercorariidae. An older name for the bird is MacCormick’s skua, after explorer and naval surgeon Robert McCormick, who first collected the type specimen. This species and the other large skuas, such as the great skua, are sometimes placed in a separate genus Catharacta. The south polar skua is a large bird (though small compared to other skuas sometimes placed in Catharacta) that measures around 53 cm (21 in) in length. Adults are greyish brown above, and have a whitish (pale morph) or straw-brown (intermediate morph) head and underparts, and the contrast between head and body makes it easy to separate from similar species with good views. Juveniles and adult dark morphs are harder to distinguish from their relatives, and more subjective or difficult-to-observe criteria, such as the colder brown plumage and blue bill base, must be used.