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DIVER

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Originally appearing in Volume V08, Page 326 of the 1911 Encyclopedia Britannica.
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DIVER , a name that when applied to a See also:

bird is commonly used dinavia, and across the See also:Russian See also:empire, it would seem, to See also:Japan, in a sense even more vague than that of See also:loom, several of the See also:sea reappearing in the See also:north-See also:west of North See also:America,* though its ducks or Fuligulinae and mergansers being frequently so called, - eastern limit on that See also:continent cannot be definitely laid down; to say nothing of certain of the auks or Alcidae and grebes; but in See also:English ornithological See also:works the See also:term diver is generally restricted to the See also:Family known as Colymbidae, a very well-marked See also:group of aquatic birds, possessing See also:great, though not exceptional, See also:powers of submergence, and consisting of a single genus Colymbus which is composed of three, or at most four, See also:species, all confined to the See also:northern hemisphere. This Family belongs to the Cecomorphae of T. H. See also:Huxley, and is usually supposed to occupy a See also:place between the Alcidae and Podicipedidae; but to which of these See also:groups it is most closely related is undecided. See also:Professor Brandt in 1837 (Beitr. Naturgesch. See also:Vogel, pp. 124-132) pointed out the osteological See also:differences of the grebes and the See also:divers, urging the See also:affinity of the latter to the auks; while, See also:thirty years later, Professor Alph. Milne-See also:Edwards (Ois. See also:foss. See also:France, i. pp. 299–283) inclined to the opposite view, chiefly relying on the similarity of a See also:peculiar formation of the See also:tibia in the grebes and divers,' which indeed is very remarkable, and, in the latter group, attracted the See also:attention of See also:Willughby more than 230 years ago. On the other See also:hand Professor Brandt, and See also:Rudolph See also:Wagner shortly after (See also:Naumann's Vogel Deutschlands, ix. p.

683, xii. p. 395), had already shown that the structure of the See also:

knee-See also:joint in the grebes and divers differs in that the former have a distinct and singularly formed patella (which is undeveloped in the latter) in addition to the prolonged, pyramidally formed, procnemial process—which last may, from its exaggeration, be regarded as a See also:character almost peculiar to these two groups .2 The See also:evidence furnished by oology and the newly-hatched See also:young seems to favour Brandt's views. The See also:abortion of the rectrices in the gerbes, while these feathers are fairly See also:developed in the divers, is another point that See also:helps to See also:separate the two Families. The commonest species of Colymbus is C. septentrionalis, known as the red-throated diver from an elongated patch of dark by which distinguishes the See also:throat of the adult in summer See also:dress. Immature birds want the See also:bay patch, and have the back so much more spotted that they are commonly known as " speckled divers." Next in See also:size is the See also:black-throated diver, C. arcticus, having a See also:light See also:grey See also:head and a gular patch of purplish-black, above which is a semicollar of See also:white striped vertically with black. Still bigger is the great northern diver, C. glacialis. or torquatus, with a glossy black head. and See also:neck, two semicollars of white and black See also:vertical stripes, and nearly the whole of the black back and upper See also:surface of the wings beautifully marked with white spots, varying in size and arranged in belts.' Closely resembling this bird, so as to be most easily distinguished from it by its yellow See also:bill, is C. adamsi. The divers live chiefly on See also:fish, and are of eminently marine See also:habit, though invariably resorting for the purpose of breeding to See also:freshwater lakes, where they See also:lay two dark See also:brown eggs on the very brink; but they are not unfrequently found far from the sea, being either driven inland by stress of See also:weather, or exhausted in their migrations. Like most birds of their build, they chiefly See also:trust to See also:swimming, whether submerged or on the surface, as a means of progress, but once on the wing their See also:flight is strong and they can See also:mount to a great height. In See also:winter their range is too extensive and varied to be here defined, though it is believed never to pass, and in few directions to approach, the northern tropic; but the See also:geographical See also:distribution of the several forms in summer requires mention. While C. septentrionalis inhabits the north temperate See also:zone of both hemispheres, C. arcticus breeds in suitable places from the See also:Hebrides to Scan- The remains of Colymboides minutus, from the See also:Miocene of Langy, described by this naturalist in the See also:work just cited, seem to show it to have been a generalized See also:form. Unfortunately its tibia is unknown. 2 A.

H. Garrod, in his tentative and chiefly myological arrangement of Birds (Prot Zool. Society, 1874, p. 117), placed the Colymbidae and Podicipedidae in one See also:

order (Anseriformes) and the Alcidae in another (Charadriiformes) ; but the artificial nature of this See also:assignment may be realized by the fact of his considering the other Families of the former order to be Anatidae and Spheniscidce. ' The See also:osteology and myology of this species are described by Dr See also:Coues (Mem. See also:Boston See also:Soc. Nat. See also:History, i. pp. 131-172, pl. 5).but it is not found in See also:Greenland, See also:Iceland, See also:Shetland or See also:Orkney. C. glacialis, on the contrary, breeds throughout the north-eastern See also:part of See also:Canada, in Greenland and in Iceland. It has been said to do so in See also:Scotland as well as in See also:Norway, but the assertion seems to lack See also:positive See also:proof, and it may be doubted whether, with the exception of Iceland, it is indigenous to the Old See also:World,* since the form observed in North-eastern See also:Asia is evidently that which has been called C. adamsi, and is also found in North-western America; but it may be remarked that one example of this form has been taken in See also:England (Prot.

Zool. Society, 1859, p. 206) and at least one in Norway (Nyt Mag. for Naturvidenskaberne, 1877, p. 134). (A.

End of Article: DIVER

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