The adult has a slate grey back; the head and neck are very dark grey, tail and under parts white. In winter the forehead and crown are white. In their first autumn the young are ash grey on the occiput, nape, and back. The tail feathers have broad black tips. Length 13 in.; wing 10·75 in. This species may always be recognised by the forked tail. THE WEDGE-TAILED GULL Rhodostethia rosea, Macgillivray This extremely scarce Arctic Gull is said to have been obtained in Yorkshire on one occasion. It may be recognised by the wedge-shaped tail. The adult is grey on the mantle; the rest of the plumage, except for a narrow black ring round the neck, is pure white. Length 13·5 in.; wing 10·25 in. BONAPARTE’S GULL Larus philadelphia (Ordigny) This is a common North American species, of which some three examples have been taken in the United Kingdom. In summer the adult has the head and neck black; mantle grey; tail and under parts white. The black on the head is lost in winter. Length 14 in.; wing 10·25 in. This species may always be recognised by the white margins to the inner webs of the two outer primaries. THE LITTLE GULL Larus minutus, Pallas This species, which is the smallest of our Gulls, is an irregular autumn visitor to our shores. It breeds in Northern Russia and possibly on some of the islands of the Baltic, migrating in winter to the Black Sea and Mediterranean. In summer the head and neck are black; mantle grey, primaries grey edged with white, rest of plumage white except the underside of the wing, which is black and forms a distinctive characteristic in the adult. Length 11 in.; wing 8·75 in. THE BLACK-HEADED GULL Larus ridibundus, Linnæus The Black-headed Gull is an extremely abundant species throughout the United Kingdom at all times of the year. In summer it resorts to various inland marshes and bogs, where it nests in immense colonies, some of which have been in use for centuries. In autumn and winter it is found all along the coast and up tidal rivers, a great many coming to London, where they are extremely tame and show great agility in catching bread and other morsels of food thrown to them by pedestrians. The bird is practically omnivorous. When inland it follows the plough and feeds largely on worms and beetle grubs which are thus laid bare; but on the sea-shore, fish, crustacea, marine insects, and garbage are greedily devoured. [Illustration: BLACK-HEADED GULL _Larus ridibundus_ Summer]