Cassell's book of birds; vol. 4

by Alfred Edmund Brehm

The DIVERS (Colymbi) may be regarded as the marine representatives of the Grebes, from which, however, they are at once distinguishable by their larger bodies, shorter neck, more bulky head, and stronger beak. These birds are fully webbed; their wings are short, and their quills, the second of which is the longest, hard and stiff; the tail is composed of from sixteen to twenty close-set feathers. The coloration of the thick warm plumage varies considerably at different seasons of the year. The number of species belonging to this group is very limited; of these only three are recognised as belonging to Great Britain; namely, C. glacialis, C. arcticus, and C. septentrionalis. The members of this group are essentially sea-birds, only visiting rivers or lakes of fresh water during the[Pg 246] breeding season or in the course of their winter migrations. Like the Grebes, they transact all their business in the water. They swim with the utmost ease to very considerable distances, and rest themselves by lying as it were flat upon the surface of the sea; sometimes, however, they sink their bodies to such a depth that only a small portion of the back is visible. Now they are seen gliding leisurely along over the tranquil waves, and now with the rapidity of lightning they disappear apparently without the slightest effort, and without causing any perceptible disturbance in the water. No sooner are they submerged, than they stretch themselves out to their full length, their feathers become flat and smooth, their wings are pressed close to their sides, and thus presenting a shape beautifully adapted to their work, they shoot through the water with arrow-like speed, now in one direction, now in another; sometimes swimming along close beneath the surface, sometimes plunging to a depth of several fathoms in pursuit of the fishes upon which they feed.

"To see them from some promontory," says Mudie, "against which the air and the sea are setting full wind and tide, and driving before them myriads of herrings and other fishes, is a glorious sight. They dash along the surface, they dart under it, they bounce up again, they bore through the advancing waves, and when the billow breaks in foam and thunders over them, and the spectator naturally concludes they are buried for ever in the deep, up they spring to the surface of the unbroken water farther from the land, as though exulting in the fury of the elements." This facility for swimming and diving they enjoy from their earliest infancy, and to it they trust as a means of escape from danger. It is seldom that they set foot upon dry land; indeed, even when they visit the shore they can scarcely be said to do so, they might rather be said to slide out of the water on to the beach; as to walking, in the ordinary acceptation or the term, that is quite out of their power—indeed, they are unable to support themselves in an upright position; by the efforts of their feet and wings, aided by their neck and beak, they creep, or rather tumble over the ground until they regain their proper element. Their powers of flight are very limited, nevertheless it is a pretty sight to see them plunge from some high cliff into the waters beneath, the efforts of their wings only serving to give an oblique direction to their downward career, as they shoot headlong into the deep, and immediately disappear beneath the waves.

The Divers appear to avoid the company of other birds, and indeed seldom associate with those of their own kind, except during the breeding season—at which time they may be seen in pairs. Their food consists exclusively of fishes overtaken in the water or brought up from the bottom of the sea; of these they seem to prefer the mid-sea swimmers, but flat fishes, such as small plaice and soles, form likewise a considerable part of their diet. Graba informs us, that from his window he has often seen them bring up flounders of considerable size, in disposing of which they showed considerable dexterity. If too large to be swallowed whole, they were dropped into the water and devoured piecemeal. Even a herring seemed to be a somewhat unmanageable morsel; but the smaller fry were at once made away with. When the breeding season approaches, all the different species of Divers betake themselves to lakes of fresh water, at some little distance from the coast, and sometimes at a considerable altitude above the level of the sea. Their harsh-sounding cry is now uttered more frequently than usual, especially towards evening, at which time they come down to the shore and throw themselves from the rocks into the ocean, in order to procure a supply of food. Their nest is generally built upon some small island in the middle of the lake or pond, or should such a situation not offer itself, upon the margin, but always close to the water; it is rudely constructed of sedge-grass and reeds, negligently heaped together and frequently without the slightest attempt at concealment, insomuch as the sitting bird is rather a conspicuous object, and may be seen from a considerable distance. Upon this rude nest the female lays two eggs of an elongated shape, having a strong, coarse-grained, but somewhat polished shell. The two sexes take their turn in the incubation of the[Pg 247] eggs, and both labour with equal zeal in the feeding and rearing of the young. The eggs are laid towards the end of May, and towards the end of June young birds may be found in the nests; but the exact period of incubation is not as yet accurately determined. Should the lake on which the nest is placed be well stocked with fish, both the parents remain constantly with their progeny; but if there is a scarcity of such a supply, and the old birds have to resort to the sea for food, they do so by turns, each of them most probably bringing to the nest a share of what they capture wherewith to feed their nestlings. These last, however, as soon as they are hatched begin to show considerable aptitude for the chase, and are able to procure food for themselves betimes. When they are fully fledged they betake themselves to the sea.

THE GREAT NORTHERN DIVER.

The GREAT NORTHERN DIVER (Colymbus glacialis) is a very striking bird, measuring about three feet in length and five feet across the wings. The length of each wing is sixteen inches and tail two inches and a quarter. In its summer plumage it is principally black, enlivened with white spots; on the head and neck the feathers are greenish black, the latter being traversed by a broad longitudinal band of black and white; a similar stripe is situated on the fore part of the neck. The sides of the upper breast are black striped with white; the rest of the under surface is a rich satiny white. The eye is light brown, and beak black; the exterior of the tarsus is grey, the under surface of a reddish flesh-colour. In its winter dress the upper part and sides are blackish, and without the white spots, and the under surface white; the breast black, streaked with white. The young are clad in a similar garb, but are without the white streaks upon the breast.

The Northern Diver is common on all the coasts of the North Sea, as well as on the inland lakes of high latitudes. It appears on the coast of Great Britain in the autumn, and remains during the winter, going at the breeding season; except at that time, it lives at sea, following the shoals of herrings and sprats; it also resorts to arms of the sea and sandy bays, floating lightly, with its body deep in the water; when alarmed, it swims with astonishing swiftness, and endeavours to escape by diving.

These birds breed on the Faroe Islands. Respecting their manner of nidification Mr. Porter, who observed them closely during the nesting season in Iceland, says:—"The Northern Diver breeds on the lochs of fresh water. In the nests I examined, a single egg was deposited. On the bare ground, but just out of water-mark, rather under a rugged bank on some broken ground, I was successful in finding two nests. I allowed the single egg to remain in one of them in the expectation that another egg would be laid to it, but was disappointed. The old bird was very shy, and always left the egg on our approach, when at a great distance off, taking to the water and keeping so far from the side as not to be within shot." In the breeding season they frequent islands, making their nests of dead herbage near the water's edge. The eggs, usually two in number, are dark olive-brown, with a few umber-brown spots, and are three inches six lines long by two inches three lines broad. The mother lies flat on the eggs, and, if disturbed, pushes herself along the ground with her feet, diving as soon as she reaches the water. The young are able in a day or two after birth to follow their mother to the water, and are able to swim and dive well. They are fed during the first fortnight with food from the crop of their parent. The voice of this bird is loud, plaintive, and much varied in tone.

Montagu tells us that, "A Northern Diver taken alive was kept in a pond for some months. In a few days it became extremely docile, would come at a call from one side of the pond to the other, and would take food from the hand. The bird had received an injury in the head which had deprived one eye of its sight, and the other was a little impaired; but, notwithstanding, it could, by incessantly diving, discover all the fish that was thrown into the pond. In default of fish it would eat flesh. It[Pg 248] is observable that the legs of this bird are so constructed and situated as to render it incapable of walking upon them. When the bird quitted the water, it shoved its body along upon the ground like a seal, by jerks, rubbing the breast against the earth; and returned to the land in a similar manner. In swimming and diving, the legs only are used and not the wings, as in the Guillemot and Auk tribes; and by their situation so far behind and their little deviation from the line of the body, it is enabled to propel itself in the water with great velocity in a straight line, as well as turn with astonishing quickness." The plumage of the Northern Diver is close, and its skin tough, on which account it is much used by the inhabitants of northern countries in the manufacture of comfortable articles of clothing. The flesh is hard and of a rank fishy flavour.

THE BLACK-THROATED DIVER.

The BLACK-THROATED DIVER (Colymbus arcticus) is smaller than the preceding species, but very much like it both in the colour and markings of its plumage. In its nuptial costume the upper part of the head and hind neck are deep ashy grey, the back and wings black, a space upon the back and another upon the hinder part of the wing are spotted with white, while upon the fore part of the wing is another space speckled with blue spots. The side of the neck presents a longitudinal black streak, the fore neck has a transverse white band, and the sides are longitudinally marked with black. The under side is white. During the winter, the head and nape are grey, the rest of the feathers on the upper surface black with white borders; the lower parts of the body are white, and the sides of the crop striped black and white. In young birds the latter markings are wanting. The eye is light brown, and the beak black. The foot is grey at its exterior, and flesh-red on the inner side. This species is from twenty-eight to thirty inches long and from fifty to fifty-two broad; the wing measures from fourteen to fifteen inches, and the tail from two inches and a quarter to two inches and a half. The Black-throated Diver is rare on our southern coasts; on the northern shores of our island it begins to appear about September. The majority of these depart about April, although a few remain to nest in the northern parts and islands of Scotland. We are indebted to Mr. Selby for the following account of its breeding, as observed by himself during the course of an excursion in Scotland.