GULL (Welsh gwylan, Breton, goelann, whence Fr. goelamf), the name commonly adopted, to the almost entire exclusion of the O. Eng. MEW (Icel. mdfur, Dan. maage, Swedish mdse, Ger. Meve, Dutch meeuw, Fr. mouetle), for a group of sea-birds widely and commonly known, all belonging to the genus Larus of Linnaeus, which subsequent systematists have broken up in a very arbitrary and often absurd fashion. The family Laridae is composed of two chief groups, Larinae and Sterninae the gulls and the terns, though two other subfamilies are frequently counted, the skuas (Stercorariinae) , and that formed by the single genus Rhynchops, the skimmers; but there seems no strong reason why the former should not be referred to the Larinae and the latter to the Sterninae.
Taking the gulls in their restricted sense, Howard Saunders, who has subjected the group to a rigorous revision (Proc. Zool. Society, 1878, pp. 155-211), admits forty-nine species of them, which he places in five genera instead of the many which some prior investigators had sought to establish. Of the genera recognized by him, Pagophila and Rhodostethia have but one species each, Rissa and Xema two, while the rest belong to Larus. The Pagophila is the so-called ivory-gull, P. eburnea, names which hardly do justice to the extreme whiteness of its plumage, to which its jet-black legs offer a strong contrast. The young, however, are spotted with black. An inhabitant of the most northern seas, examples, most commonly young birds of the year, find their way in winter to more temperate shores. Its breeding-place has seldom been discovered, and the first of its eggs ever seen by ornithologists was brought home by Sir L. M'Clintock in 1853 from Cape Krabbe (Journ. R. Dubl. Society, i. 60, pi. i); others were subsequently obtained by Dr Malmgren in Spitsbergen. Of the species of Rissa, one is the abundant and well-known kittiwake, R. tridaclyla, of circumpolar range, breeding, however, also in comparatively low latitudes, as on the coasts of Britain, and in winter frequenting southern waters. The other is R. breviroslris, limited to the North Pacific, between Alaska and Kamchatka. The singular fact requires to be noticed that in both these species the hind toe is generally deficient, but that examples of each are occasionally found in which this functionless member has not wholly disappeared. We have then the genus Larus, which ornithologists have attempted most unsuccessfully to subdivide. It contains the largest as well as the smallest of gulls. In some species the adults assume a darkcoloured head every breeding-season, in others any trace of dark colour is the mark of immaturity. The larger species prey fiercely on other kinds of birds, while the smaller content themselves with a diet of small animals, often insects and worms. But however diverse be the appearance, structure or habits of the extremities of the series of species, they are so closely connected by intermediate forms that it is hard to find a gap between them that would justify a generic division. Forty-three species of this genus are recognized by Saunders. About fifteen belong to Europe and fourteen to North America, of which (excluding stragglers) some five only are common to both countries. Our knowledge of the geographical distribution of several of them is still incomplete. Some have a very wide range, others very much the reverse, as witness L. fuliginosus, believed to be confined to the Galapagos, and L. scopulinus and L. bulleri to New Zealand, the last indeed perhaps only to the South Island. The largest species of the group are the glaucous gull and greater black-backed gull, L. glaucus and L. marinus, of which the former is circumpolar, and the latter nearly so not being hitherto found between Labrador and Japan. The smallest species is the European L. minutus, though the North American L. Philadelphia does not much exceed it in size. Many of the gulls congregate in vast numbers to breed, whether on rocky cliffs of the sea-coast or on healthy islands in inland waters. Some of the settlements of the black-headed or " peewit " gull, L. ridibundus, are a source of no small profit to their proprietors, the eggs, which are rightly accounted a great delicacy, being taken on an orderly system up to a certain day, and the birds carefully protected. Ross's or the roseate gull, Rhodostethia rosea, forms a well-marked genus, distinguished not so much by the pink tint of its plumage (for that is found in other species) but by its small dove-like bill and wedge-shaped tail. It is an exceedingly scarce bird, and beyond its having an Arctic habitat, little has yet been ascertained about it. More rare still is one of the species of Xema, X. furcatum, of which only two specimens, both believed to have come from the Galapagos, have been seen. Its smaller congener Sabine's gull, X. sabinii, is more common, and has been found breeding both in Arctic America and in Siberia, and several examples, chiefly immature birds, have been obtained in the British islands. Both species of Xema are readily distinguished from all other gulls by their forked tails. (A. N.)
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)