THE KITTIWAKE GULL Rissa tridactyla (Linnæus) With the Kittiwake we come to a species of Gull which differs in its general build from those we have hitherto dealt with. It is rather shorter in the leg, which gives it a somewhat “squat” appearance, and it does not run about on land with the same facility. In correlation with this we find it to be a much more pelagic species, and though found commonly round our shores, it gets most of its food on the water and is rarely to be found among the large flocks of other Gulls that spend much of their time on the shore itself. Its food consists almost entirely of fish, in pursuit of which it dives and swims under water with ease. It nests on the ledges of precipitous cliffs in immense colonies, and in some cases the population of these colonies must amount to very many thousands. The nest is built of seaweed and other flotsam, and is often larger than the narrow ledge on which it is placed. The eggs, two or three in number, are usually pale greyish white, blotched and zoned with ash grey and brown; the shell is rougher in texture than in the other species. They are laid very late in the season, so that it is generally July before the young are hatched. Both sexes take part in the incubation, and the young are entirely nidicolous, not leaving the nest till they are well able to fly. In summer the adults very closely resemble the common Gull, but it is a smaller bird, and the black legs, on which the hind toe is absent, form an unfailing characteristic. In winter the nape and hind neck are grey like the mantle. Length 15·5 in.; wing 12 in. The young bird in its first autumn has the nape greyish but darker than in the adult, and the wing coverts and inner secondaries are thickly spotted with brownish black. [Illustration: KITTIWAKE _Rissa tridactyla_ Summer (below). Winter (above)] THE IVORY GULL Pagophila eburnea (Phipps) Some thirty or forty examples of this Arctic Gull have been taken in these islands; it is entirely circumpolar in distribution and breeds on Spitzbergen, Franz Josef Land, Novaya Zemlya, and other Arctic regions. The adult is entirely white; bill greenish grey with a red tip; legs black, the hind toe being well developed. The young bird is mostly white, but spotted on the back, wings, and tail with brownish black. Length 18 in.; wing 13 in. THE GREAT SKUA Megalestris catarrhactes (Linnæus) The Skuas are a group of birds closely allied to the Gulls, being very similar in general build, but both the claws and beaks are sharper and more hooked.