The shag may be easily mistaken for the cormorant, which it closely resembles, but when near at hand is seen to differ in its smaller size and its prevailing green colour, which appears black at a distance; and, in the breeding season, by the absence of the white patch on the flank. In its habits it is more strictly marine than the cormorant, but resembles that bird in its manner of swimming and flight. It prefers bays and inlets to the open sea, and deep water near rocks to the shallow sea, where there is a low beach. In diving after fish it springs upwards almost out of the water, and goes down head first. Beneath the water it propels itself wholly by its feet; the auks, and some other diving birds, use their wings as fins to assist progression. After capturing a fish the shag brings it to the surface to swallow it, then swims on for a space, and dives again, and so on, and finally returns to the rock, where it proceeds to disgorge its prey, to devour it at leisure. The shag breeds on sea-cliffs, sometimes building on the ledges or in crevices, but caves, where they exist, are preferred. The eggs are three in number, in shape and colour like those of the cormorant, and the nests, which are placed close together, are also like those of that bird.
The shag is found in certain localities all round the coasts of Great Britain and Ireland, but is less numerous and more local than the cormorant.
Gannets. Guillemots. Herring-Gulls.
Gannet.
Sula bassana.
Adult: head and neck buff-colour; all the rest of the plumage white, except the primaries, which are black. Young of the first year: upper parts blackish brown necked with white; under parts mottled with dusky ash and buff. The dark markings diminish until the sixth year, when the adult colouring is assumed. Length, thirty-four inches.
One of the most notable seafowls inhabiting the British coasts is the gannet, or solan goose, a species which forms a connecting-link between the cormorants and the pelicans. The origin of its two common names is not precisely known, although it seems probable that gannet is derived from gans, the ancient British name for goose. The young birds from the Bass Rock, which are largely used as food in the neighbouring counties, are called, I do not know why, ‘Parliamentary geese.’ The world will have it that the bird is a goose, although as little like a goose, except in size, as a guillemot is like a sheldrake. The scientific name, bassana (of the Bass Rock), had its origin in the belief that the rock at the entrance to the Firth of Forth was the gannet’s only breeding-place. There are several other colonies: one, now greatly diminished, on Lundy Island; another, also small, on the coast of Pembrokeshire; on the West Coast of Scotland there are four stations, and others exist on the Irish coast. None of these, however, can compare in importance with the Bass Rock, where it has been calculated that as many as ten thousand pairs congregate each year to breed.
The gannet is an exclusively marine bird, and an inhabitant throughout the year of the seas round the British Islands. Its flight is easy and powerful, and its appearance on the wing more pelican- than cormorant-like. It feeds entirely on fish, and follows the shoals of such species as swim near the surface—mackerel, herrings, pilchards, and sprats. When fishing it sails at a considerable height, and on catching sight of its prey rises to a greater height, and then, with wings nearly closed, drops straight down, with great force, into the water. Its appearance when falling has been likened by one observer to ‘a brilliant piece of white marble.’