Part 55

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.

As a rule they chase Gulls and Terns, compelling them by so doing to disgorge their last meal; this the Skua then devours, leaving the Gull in peace to hunt for more. They are not, however, always content with this second-hand dinner, but sometimes kill and eat the Gulls themselves; they also devour offal and carrion.

The Great Skua is a scarce species, and is but seldom seen round our shores. The only breeding-stations within the United Kingdom are on two islands of the Shetlands, where it is strictly protected. During the winter, unless driven inshore by stress of weather, it keeps out at sea, remaining near the Gulls on the fishing-grounds.

The nest is a "scrape" among the heather on the highest part of some island, and the eggs, two in number, are olive brown with darker markings. In defence of their home this species is very bold, sweeping down continually at an intruder and even striking at him with their wings.

The sexes are alike, and are dark brown above with chestnut and whitish mottlings; below they are of a uniform rufous brown. The claws are hooked and sharp. Length 21 in.; wing 16 in.

The young resemble their parents.

THE POMATORHINE SKUA Stercorarius pomatorhinus (Temminck)

This bird, especially when immature, is not very rare on our eastern shores during the autumn migration in September and October, a few even wintering off our south coast. On the return migration in spring it is very rarely seen.

It breeds in Eastern Siberia and thence eastward across Arctic America to Greenland.

The adult has the head sooty black. The hind neck whitish with straw yellow acuminate feathers. Upper parts brown, two central tail feathers longer than the rest and twisted vertically. Under parts whitish, except the flanks and abdomen, which are brown. Length 21 in.; wing 14·25 in.

The young bird in its first autumn is brown mottled and barred with dull rufous. It takes more than a year to assume the full adult plumage.

THE ARCTIC OR RICHARDSON'S SKUA Stercorarius crepidatus (J. F. Gmelin)

This is the commonest of the Skuas, occurring on all the Scottish coasts and being fairly common in the east of England every autumn. In Ireland and the west of England it is only an irregular straggler.

It breeds in the Shetlands, Orkneys, and the north of Scotland, some moor at no great distance from the sea being chosen as a summer home. No nest is made, but a depression is formed in the moss or grass on which the two brownish green eggs, blotched with darker brown, are laid. The young when first hatched are covered with dark brown down.

In its habits and food it does not differ from the other Skuas.

This species is dimorphic, one form having light under parts, and the other being of a uniform sooty brown all over. The light-coloured birds predominate in the north of their breeding area and the dark ones in the south, but when they meet they breed indiscriminately, and intermediates of all shades are found. The central tail feathers are longer than the rest. Length 20 in.; wing 13 in.

The young vary considerably, but are usually brown, mottled and spotted with chestnut, while in some the chestnut colour is almost entirely wanting.

THE LONG-TAILED OR BUFFOUS SKUA Stercorarius parasiticus (Linnæus)

This is a rare species to all our shores, but a few, chiefly immature birds, visit the east coast yearly, and in some seasons become quite common. It is a circumpolar species, breeding on the tundras throughout Europe, Asia, and America, and migrating in winter as far south as the basin of the Mediterranean.

In its habits it resembles other Skuas, but in addition to robbing Gulls, it feeds largely on beetles and worms, and the young eat a large quantity of crowberries when in their summer-quarters.

The adult has the top of the head black, cheeks and hind neck buffish yellow, mantle and tail, the two central feathers of which are much elongated, grey brown, wings darker. Under parts chiefly white, brownish on the flanks and belly. Length 23 in.; tail 8·5 in.; wing 11·9 in.

Immature birds are barred above and below with brown and yellowish white. It is sometimes rather difficult to distinguish between the young of this and the preceding species; the present species is, however, always much greyer and less rufous, and has the shafts of the two outer primaries white, the rest being dusky, whereas in the Arctic Skua the shafts of all the primaries are white.

THE RAZORBILL Alca torda, Linnæus

The Alcidæ are pre-eminently pelagic birds that spend their whole life out on the ocean except for a few short weeks every year, when they assemble in thousands on precipitous cliffs to breed.