Although not very rare, this bird is seldom seen, as it spends most of its time at sea in attendance on the fishing-boats or on the banks where the fish abound. In Scotland it nests on St. Kilda and a few of the other islands of that group; while in the Shetlands, where it was first known to nest in 1878, it has now spread to several of the neighbouring stacks.

The nest is placed on a ledge on the face of a precipitous cliff, and the single egg is pure white with a few reddish-brown spots. The young are at first nourished on a yellowish oil vomited by the parent birds, and large numbers are annually taken in St. Kilda for the sake of this oil. It may easily be distinguished from a Gull on the wing by its peculiar flight and rounded wings.