Skuas are the size of a Western gull, dark with a pale nape and large white patches on the bases of the primaries on both the upper and lower surfaces.

This is a solitary bird. Its flight is low and direct with heavy flapping and little gliding. It steals food from other seabirds, and is aggressive, bordering on predatory. It may grab a shearwater's head, wing, or tail and shake and kick the bird until it regurgitates its food.

Chances of detection are best around flocks of shearwaters feeding behind fishing boats. It is a rare to uncommon fall transient offshore. Skuas arrive in late June and are present in low numbers from late July-Aug to mid October.

Hear the call of the South polar skua

Photo by Tony Morris, Flickr