British Sea Birds

CHAPTER IV.

DIVERS, GREBES, AND CORMORANTS

The birds included in the present chapter belong to three well-defined families. None of them are so completely pelagic as the Auks, and yet, according to season, many of them are interesting features in the bird-life of the coast. Unfortunately for the summer visitor to the seaside, the Divers will be absent. They are birds that resort chiefly to inland districts to rear their young, or are only known as winter visitors to the British Coasts. The Divers form a small but well-marked family known as Colymbidæ, consisting of a single genus Colymbus, into which are grouped the four species that are now known to science. The Divers are allied to the Auks on the one hand, to the Grebes on the other, although systematists are not yet agreed upon the degree of their relationship. United, these three families form Dr. Sclater’s order Pygopodes. In every way the Divers are remarkably well fitted for an aquatic life. Their strong tarsi are laterally compressed, a form best suited for cleaving the water, the hind toe is well developed, and on the same plane as the rest, the feet are webbed, the bill is long, straight, spear-shaped and conical, admirably adapted for seizing the finny prey, the wings are comparatively short, yet capable of bearing the bird at great speed, the tail is short and fairly developed. The Divers in nuptial plumage are remarkably handsome birds, the neck being striped or richly marked, and the upper plumage beautifully spotted or adorned with white bars. They are all more or less gregarious birds during winter, and well marked social tendencies are displayed in some species during the breeding season. Their migrations, if comparatively short, are pronounced and regular. The young are hatched covered with down, able to swim with ease almost immediately. Adults moult in autumn, and assume their nuptial plumage in winter – a period doubtless when they pair – the winter plumage thus being carried for a short time. Young Divers carry their first plumage through the winter until the following spring (not moulting in December with their parents), when they assume their summer plumage, but the nuptial ornaments are not so brilliant in colour as in adults. Whether the vernal change in colour is effected without moulting, as in the Auks and some of the Limicolæ, appears not to have yet been ascertained. All the species of Divers are visitors to the British Islands, but only two breed in them, and one is an exceptionally irregular straggler. This is the largest of them all, the White-billed Diver, Colymbus adamsi, and a species apparently circumpolar in its distribution. The Divers are all birds of the north-temperate or Arctic regions, during summer; in winter their range is much more extended, almost reaching to the northern tropics. With this brief résumé of their more salient characteristics, we will now proceed to a more detailed examination of their economy.

This species, the Colymbus glacialis of Linnæus and of ornithologists generally, is, in its breeding plumage, one of the handsomest of British birds. Its chief characteristics are its large size – about that of a Goose – black head and neck, double semi-collars of white and black vertical stripes, and black upper parts, marked with white spots of varying size, and arranged in a series of belts. Whether it actually breeds within our limits has not yet been absolutely determined, although evidence is forthcoming that seems to point to the fact. Unfortunately for the seaside student of bird life, the Great Northern Diver is only known as a winter visitor. At that season, however, it may be met with pretty frequently off the British coasts, the young birds especially venturing into our bays and creeks and estuaries, older individuals, as a rule, keeping further out to sea. Adult birds are, however, often observed near the coasts of South Devonshire and Cornwall. I have known them linger in the waters near here until the summer has been well advanced. Young birds of this species, in the brown and white dress characteristic of immaturity, may often be seen quietly fishing under the cliffs, notably in Tor Bay. One very remarkable thing about this Diver is its singular habit of immersing the body to such a depth that the back is quite under water. It often so sinks itself when menaced by danger, and then, almost out of sight, swims away with great speed. If pursuit is still continued all but the neck is sunk below the surface, and finally, if hotly pressed, the bird will disappear entirely, and swim along under water at a speed absolutely astonishing, Gätke records that this Diver, when chased by a boat under these circumstances, will dive and allow the boat to pass over it, rising again in the rear of it, a habit which my own observations of the bird completely confirm. How this act of immersion, without apparent effort, is accomplished remains a mystery, and offers a problem in animal mechanics by no means easy of solution.

The Great Northern Diver is rarely seen on land, perhaps never except during the breeding season. Its movements on shore are ungainly in the extreme, the legs being placed so far back that the bird can only push itself along in a crawling sort of a way; it is equally rarely seen in the air, and apparently only uses its wings to fly when performing its annual migrations. How the species still retains the function of flight at all seems almost a mystery, but perhaps the constant use of the wings in the water keeps them to a standard of efficiency. This Diver is one of the least gregarious, and save on passage is rarely met with in numbers greater than a pair. It seems to be the rule for odd pairs to take up their residence in certain spots during the breeding season; after that period the bird is usually met with solitary, and the young individuals, unlike so many others that evince strong gregarious propensities, for the most part wander about alone. This Diver, like most big birds, is shy and wary, although I have repeatedly watched it from the cliffs in Tor Bay evincing little concern at my presence. As may be gathered from the foregoing remarks the Great Northern Diver is a proficient in the art of diving, and is said to be able to remain as long as eight minutes beneath the surface – a period of time which seems incredible. The depth to which it sometimes descends is also enormous – it has been captured in a net thirty fathoms from the surface. The food of this Diver is almost, if not absolutely, composed of fish. During the non-breeding season Divers are not particularly noisy birds, but at their nesting-places the cries they utter are both loud and startling, described by some listeners as similar to the screams of tortured children; as shrieks of maddened laughter, or as weird and melancholy howls by others.

It is a somewhat remarkable fact that the Great Northern Diver breeds nowhere in Europe, except on Iceland. It is an American species, and nests from Greenland westwards to Alaska, south of the Arctic circle to the more northern of the United States. It reaches its breeding-grounds in pairs towards the end of May, as soon as the northern waters are free from ice. Its favourite nesting places are secluded tarns and lakes, and an island is always selected if possible, doubtless from motives of security. The nest – always made upon the ground – varies a good deal in size, according to the local requirements. On wet marshy ground it is large, and composed of a heap of half rotten sedges, rushes, reeds, and such like vegetation, lined with dry bits of broken reed and withered grass. On drier and barer situations it is little more than a hollow in the sand or hard ground, with, perhaps, a few bits of dry grass for lining. The birds are very alert and watchful whilst nesting, as if fully conscious of their comparative difficulty in escaping from danger on the land. One bird is generally on the look out whilst the other sits, and at the least danger the alarm is given, and the incubating partner shuffles off in a floundering way to the water. A path is soon thus worn from the nest to the lake. The eggs are almost invariably two, elongated, and varying in ground colour from russet-brown to olive-brown, spotted sparingly with blackish-brown and paler brown. When the young are sufficiently matured, the inland haunts are deserted, and the nomad wandering life upon the sea resumed.

The present species of Diver (much smaller than the preceding), the Colymbus arcticus of Linnæus and most other writers, is the rarest of the three that visit the British Islands regularly, and perhaps we might also say the most beautiful in nuptial dress. All its showy colours and patterns, however, are on the head, neck, and upper parts, the under surface being white. The head is gray, the throat patch black, above which is a semi-collar of white striped vertically with black; the sides of the neck are also striped with black and white; whilst the black upper parts of the body are conspicuously marked with a regular series of nearly square white spots, becoming oval in shape on the wing coverts: the bill is black, the irides crimson. After the autumn moult all this finery is lost, and the upper parts become a nearly uniform blackish-brown. This Diver breeds sparingly in various parts of the Hebrides and the Highlands, from Argyll to Caithness; elsewhere it is only known as a winter visitor. In many of its habits it closely resembles the preceding species. It is exclusively aquatic, only seeking the land during the breeding season, but is, perhaps, not quite so oceanic as that bird in the winter, when it not unfrequently haunts inland waters. It dives with equal skill, flies with the same powerful rapidity, and utters during the nesting season very similar unearthly cries. Fish form the chief food of this Diver, but it is said also to capture frogs. Most of the examples of this Diver that are seen close in-shore (on our eastern and southern coasts principally) during winter are immature, the older birds as a rule keeping further out to sea. The Black-throated Diver indulges in the same peculiar habit of gradually sinking its body in the sea when alarmed, and will frequently seek to escape pursuit by diving outright, and swimming under water for a considerable distance.

The Black-throated Divers that breed with us, retire to their inland haunts in May. Its favourite nesting places are on islands in moorland lochs, pools, and tarns. It displays few social tendencies at this season, although several pairs not unfrequently nest within a comparatively small area of exceptionally suitable country, each, nevertheless, keeping to its own particular haunt. This Diver may also pair for life, seeing that it evinces considerable attachment to certain favourite nesting places. The nest is always made upon the ground, and seldom very far from the water, to which the frightened bird can retire readily. An island covered with short herbage is always preferred in Scotland, but in some places the bare shingly beach is selected. This nest, often of the slightest construction, is made of stalks of plants, roots, and all kinds of drifted vegetable fragments, lined with grass. Sometimes no nest whatever is made. The two eggs are narrow and elongated, olive- or rufous-brown, sparingly spotted and speckled with blackish-brown and paler brown. The sitting bird is ever on the alert to slip off into the water at the first alarm; and sometimes both birds will fly round and round in anxiety for the fate of their treasured eggs. A movement seawards is soon taken when the young are sufficiently matured. This Diver has a wide geographical range outside our limits, extending across Europe and Asia to Japan and North-west America, perhaps as far as Hudson Bay. American authorities, however, insist upon the specific distinctness of most of the Black-throated Divers found in Alaska, and have named this form C. pacificus.

Smallest of the British Divers, the present species, the Colymbus septentrionalis of Linnæus and modern authorities, is also the best known and the most widely distributed. It is also the least showy in nuptial dress. In this plumage the throat is marked with an elongated patch of chestnut; the head, and sides of the neck are ash-brown, the latter striped with black and white, the general colour of the upper plumage blackish-brown, sparingly spotted with white, and the under parts are white. The plumage, as in all the Divers, is remarkably dense and compact, adapted in every way to the aquatic habits of the bird. The Red-throated Diver is a fairly frequent visitor, during autumn and winter, off the English coasts, often entering bays and the mouths of wide rivers. In summer, however, it becomes much more local, retiring then to haunts in Scotland, especially in the Hebrides and along the wild and little populated western districts, from the Clyde northwards to the Shetlands. Outside our limits, this Diver has a very wide distribution, occupying in summer the Arctic and north temperate regions of Europe, Asia, and America; in winter migrating southwards for a thousand miles or more. The Red-throated Diver is certainly the most gregarious species, and in winter may not unfrequently be seen in gatherings of varying size. In connection with this trait, mention may be made of the extraordinary numbers of this bird that, on the 2nd and 3rd of December 1879, passed Heligoland. The movement was not strictly a migratory one, but a grand flight of storm-driven, frozen-out birds, seeking more congenial haunts. Gätke tells us that during this visitation, there was about thirteen degrees of frost, an easterly wind, and a snowstorm in the evening. The Divers were by no means alone in their distress, for hundreds of thousands of Ducks, Geese, and Swans, Curlews, Dunlins, and Oyster-catchers, passed from east to west. From early morning until noon, on both days in succession, the Divers were seen in one incessant stream, travelling north-east, in numbers estimated almost by the million! Well may Gätke have wondered whence such vast multitudes came, and whither they were going, and what was the initial cause of such gregarious instincts, never manifested in this Diver under any ordinary circumstances.

The Red-throated Diver is a master at the art of diving, and is often seen slowly to sink its body under water when alarmed. It also flies with great strength and speed, and is said to show more preference for flying than either of its congeners. The food of this Diver is chiefly composed of fish. Its ordinary note is a harsh ak or hark; but at the nesting places the same wild unearthly cries are uttered that are equally characteristic of the other species. These cries are said to foretell rain or rough weather, and have caused the bird to be called “Rain Goose” in many Highland districts. The Red-throated Diver, however agile and graceful it may be in the water or even in the air, is a clumsy object on the land, incapable of walking upright, owing to the backward position of its legs, and compelled to shuffle along with its breast touching the surface. In winter these Divers are by no means shy, and I have many times watched them pursuing their fishing operations, from my station on the cliffs.

In May, the Red-throated Diver retires to its breeding stations – the wild romantic lochs and pools so characteristic a feature of the Highlands and the Hebrides. Solitary pairs generally scatter themselves over a district, resenting intrusion, and keeping to their own particular haunt. This Diver probably pairs for life, returning each successive season to a certain spot to nest. An island is usually selected for the nest, which is invariably made upon the ground, and consists generally of little more than a hollow, into which is collected a few bits of withered vegetation. As may be expected, this nest is seldom made far from the water, so that at the least alarm the sitting bird can slip off and shuffle into the water at once. The two narrow elongated eggs are olive- or buffish-brown, spotted and speckled with blackish-brown and paler brown.

In many respects Grebes are remarkable birds. They form so well defined a group that no other known bird can possibly be confused with them, their characteristics being absolutely unique among the class Aves. The most noticeable external features of a Grebe are its relatively short body, laterally compressed tarsi, lobed feet, rudimentary and functionless tail, and dense compact plumage of a peculiar silky texture. The twenty or so species of Grebes are grouped into a single family, called Podicipedidæ, of which the genus Podiceps (or more correctly Podicipes) contains the greater number. The Grebes are almost cosmopolitan. Five well-marked species are found in Europe, all of which, being visitants or regular residents, are included in the British avifauna. In the colours of their plumage the Grebes are not very remarkable, with the exception of the crests or tippets assumed by some species during the nuptial period: plain browns predominate on the upper surface; the underparts are almost always glossy white. The Grebes fly well; dive with great dexterity, but their movements on the ground are not graceful. The young are hatched covered with close down, and able to swim at once. The Grebes have a complete moult in autumn, and assume their nuptial ornaments in spring. The quill feathers are moulted so rapidly that for some little time the birds are unable to fly, as is the case with the Geese and some others.

It is only during the winter months that the Grebes become pelagic or marine in their habits, and even some species are much less addicted to a sea life than others. We will now proceed briefly to glance at the British species.

This, the largest species, the Podicipes cristatus of naturalists, is chiefly an inland bird, but resorts to the sea when fresh waters are frozen. I have sometimes met with half a dozen together in a quiet bay, under these circumstances, and very graceful interesting birds they are. They rarely come upon the land at these times, swimming about and diving from time to time in quest of food. Like the Divers, they sometimes sink the body very low in the water, but under ordinary conditions sit rather high, with the long neck held well up, the head turned at intervals in all directions as if on the look out for enemies. They always prefer to dive when pursued; and as this species more especially is in great demand by plumasiers, and subject to much persecution, it is wary and shy in extreme. The food of this Grebe whilst on the sea is composed largely of fish, but inland the bird’s tastes are more omnivorous. Sometimes many of its own feathers are found in its stomach, mixed with the food, but as yet ornithologists have been unable to assign any plausible explanation of the fact. In Spring, the adults assume two very conspicuous crests or horns of a dark brown colour, and a tippet or ruff of bright bay, shading into nearly black on the margin. The birds now retire inland to meres and lakes, where the shallows are full of reeds, sedges, rushes, and other aquatic vegetation, and here, at some distance from the shore, a large floating nest is made, composed of dead and decaying vegetation. As the bird is sometimes gregarious several nests may often be found within a small area – huge floating rafts moored to the reeds, or built up from the bottom of the shallow water. In a shallow depression at the top four or five eggs are laid, elliptical in shape, chalky in texture, and white, until contact with the bird’s wet feet and the wet nest covers them with stains. Several mock nests are often made in the vicinity of the one containing the eggs, probably destined as resting places for the future young. The sitting bird very dexterously covers its eggs with weed when alarmed, previous to slipping off the nest into the water. The note of this Grebe is a loud kak.