Head and neck violet-black, the latter with a double interrupted white collar: bill upwards of four inches in length; the upper mandible nearly straight.
C. glacialis, Temm. Man. d'Orn. torn. it. p. 910. Northern Diver, Mont. Orn. Diet. Selb. Must. vol. ii. p. 406. pl. 76. Great Northern Diver, Bew. Brit. Birds, vol. ii. p. 174.
Entire length thirty-three inches: length of the bill (from the forehead) two inches eleven lines, (from the gape) four inches one line; of the tarsus three inches; of the middle toe, nail included, four inches two lines; of the tail three inches six lines; from the carpus to the end of the wing thirteen inches six lines.
(Adult). Head and neck velvet black, with green and purple reflections; beneath the throat a transverse semilunar white band with black streaks; on the lower part of the neck an interrupted broad collar, streaked longitudinally with black and white: all the upper parts black, elegantly spotted with white; the spots on the back and rump small and round; those on the scapulars larger and of an oblong-square form, disposed in rows, two at the extremity of each feather: quills and tail without spots: breast and other under parts white; flanks and sides of the breast with a few black streaks: bill black; the ridge of the upper mandible very slightly arched above; lower mandible channelled beneath, appearing deepest in the middle; the gonys sloping upwards to the tip; tomia of both mandibles, but particularly of the lower one, inflected: irides brown: feet externally dusky brown; the inner portions, and membranes between the toes, whitish. (Young of the year). Head, occiput, and all the back part of the neck, cinereous brown; cheeks speckled with white and ash-colour; throat, front of the neck, and all the other under parts, pure white; the feathers on the back, wings, rump, and flanks, deep brown in the middle, the edges and tips ash-colour: upper mandible cinereous gray; lower mandible whitish. At the age of one year, a transverse bar of dusky brown appears on the middle of the neck, forming a sort of collar; the back assumes a dusky tint, and the small white spots begin for the first time to shew themselves. At the end of the second year, the dusky bar on the neck extends further; the brown on the head and nape becomes mixed with greenish black; the spots on the back and wings increase in number, and the band on the throat, and collar on the lower part of the neck, are more distinctly indicated by longitudinal streaks of brown and white. At the age of three years, the plumage is perfect. (Egg). Dark olive-brown, with a few spots of umber-brown: long. diam. three inches six lines; trans, diam. two inches three lines.
A native of high northern latitudes. Abundant in the Orkneys, Hebrides, and other Scotch islands, but very rare in the southern parts of Britain. Has been taken in Cornwall, Bedfordshire, and occasionally, in the immature state, on different parts of the English coast. Seldom flies, but dives well. Feeds on fish, particularly herrings. Nest said to be placed on the borders of fresh-water lakes, or in small islands. Eggs two in number. Obs. In its immature state, this species is the C. Immer of authors, but it is probable that in some cases this name has been also applied to the young of the next species.