The Black Guillemot differs in many respects from the other Auks and it is never found in vast colonies, though several pairs will often breed in close proximity. Some hole or recess in a cliff or among broken rocks on a steep slope is chosen and two eggs are deposited, which are whitish spotted with grey and brown and elliptical in shape. Both sexes take part in the incubation, and the young are said not to leave the nest until they are fully fledged. Their food consists of fish and crustaceans, which they obtain by diving. The sexes are alike in plumage, and in summer are of a uniform sooty brown all over, with the exception of a patch on the wing, which is white. Bill black. Legs vermilion red. In winter the crown is black marked with white, the back barred with black and white, and the rest of the plumage white. The young resemble the adults in winter but are rather whiter. Length 14 in.; wing 6·5 in. THE LITTLE AUK Mergulus alle (Linnæus) This species is an inhabitant of Arctic seas, breeding in Greenland, Spitzbergen, and Franz Josef Land, but it does not occur in Arctic America nor to the east of the Kara Sea. In winter it migrates southwards and a few are found round our northern shores every year, but in severe winters it often occurs in considerable numbers, and many storm-driven birds are found in a dying condition far inland. There is a small white spot over the eye, but otherwise the plumage is sooty black on the upper parts. The under parts are white, but in summer the chin and throat are black. Length 8·5 in.; wing 4·65 in. [Illustration: BLACK GUILLEMOT _Uria grylle_ Summer (below). Winter (above)] PUFFIN Fratercula arctica (Linnæus) One of the most fascinating points in connection with this quaint bird is that for at least six months in every year we know nothing, or comparatively nothing, of its habits or whereabouts. Towards the middle of April it suddenly appears at certain well-known haunts and proceeds forthwith to set up housekeeping. A hole or cranny in a rock or, where possible, a rabbit-burrow is fixed upon as its home, and the same entrance is often shared by several pairs as well as the rabbit. A weird little creature is our friend as he sits bolt upright on his doorstep, turning round every now and again to bill and coo with his mate, their large orange-red beaks and feet showing up brightly against their black-and-white plumage. The wings are so short that this bird finds some difficulty in rising from a flat surface, and when on the wing will often fly round in spiral curves in order to reach the summit of the cliff. In flight the legs are held spread out behind on either side of the very short tail and help to act as rudders.