The nest itself is more or less artistically constructed of twigs, stalks, straw-grass, leaves, and similar materials, always well and warmly lined with down. The brood consists of from eight to fourteen eggs, but by regularly abstracting them as they are laid, the female will sometimes produce double those numbers. The eggs are well-shaped, rather elongate, slightly shining, and of a delicate greenish brown, grey, or dirty olive-green colour. Only the female sits, and upon her the guardianship of the young brood almost entirely devolves. Such as are born in nests placed at a considerable height, must necessarily be brought by her to the surface of the ground, but we are not aware that any naturalist has witnessed such a proceeding. It is just possible that, like some Ducks and Geese, they may leap from the nest trusting to their fluttering wings and thick downy covering to come off scatheless. Were we to judge by the observations we have had opportunities of making relative to the breeding of the Red-breasted Merganser (Mergus serrator), we should say that the young brood at first comport themselves exactly like young Ducks; soon, however, their natural peculiarities and special endowments begin to show themselves, and after the lapse of about eight days, they adopt the habits of their race. When first hatched they live upon small crustaceans and larvæ, caught upon the surface of the water, but on the third day are able to dive, and from the eighth day are quite[Pg 174] capable of fishing for themselves. They grow very rapidly, and soon become independent. According to Naumann the instinct for brooding is so strong in these birds, that if robbed of their eggs, they will take possession of the nest of a Duck, and after forcibly driving away its owner, will sit upon her eggs till they are hatched.
[Pg 175]
THE SEA-FLIERS (Longipennes).
IN the broad-billed water birds, we have had an opportunity of admiring the manner in which their power of swimming becomes more and more complete. In the Sea-fliers we shall recognise the tyrants of the ocean, seeing that in their presence the swimming birds, whether inhabitants of the coast or children of the wave are subservient. The great character whereby the Longipennes are distinguished is the enormous development of their wings, while that of their feet remains comparatively in abeyance. Some of them, it is true, are well able both to swim and to walk, but their special adaptation is for flight. Their power of flying is supreme, and in this they are surpassed by no other birds. As to their general structure, there is a great similarity between the different races. Their body is powerful, their neck short, and their head of moderate size. Their beak, which is of medium length, is compressed at the sides and sharp-pointed or hooked at the end; in conformity with this structure, the upper mandible is more or less arched, while the under jaw at a little distance from its apex, is strengthened by an angular enlargement. Their feet are feeble in proportion to the size of their bodies, and only webbed upon the three anterior toes; moreover, even upon these the webs are often very imperfectly developed. The wings are always long, and sharp-pointed, more or less narrow and proportionately very large; their tail is of moderate dimensions, either truncate, greatly rounded, pointed, or forked at the extremity, and usually composed of twelve feathers. The general plumage is very thick and rich, but not particularly well-furnished with down; its colour is much varied, and changes with the age of the bird and at different seasons. In all the above characters and in many others that might be adduced from an examination of their internal structure, these birds differ from the Swimmers in so many particulars that they cannot be considered as in any way belonging to the same order.
The domain of the Sea-fliers is the ocean, their territory the wide world. Some families seem more especially to frequent coasts, others prefer fresh water to the salt sea, but these are mere exceptions. Sweeping continually over the waves, or skimming in the proximity of coasts, they wander over the sea and circle round the globe. By one tie only are they bound to the dry land, and that is, their affection for their offspring. They lay their eggs upon the land, and there watch over their young brood until their wings attain sufficient strength to enable them to join their brethren in the air; the rest of their time is for the most part devoted to the sea, upon which they sometimes repose, or, in exceptional cases, sleep upon the shore. Their flight is longer sustained than that of the Swallows or Swifts, or even of the Humming-birds, for they fly not only during the whole day but often likewise throughout the night. It is to this untiring energy and constant restlessness that we must attribute the boundless range over which particular species spread themselves. Some of them indeed have literally a world-wide distribution, and visit every climate between the equator and the polar seas. Others again, restrict their wanderings, or migrations, or flights, or whatever the reader may choose to call them, either within more or less definite regions, or within certain degrees of latitude; it must, however, be kept in mind that these boundaries are not coasts or countries, but whole continents and oceans.
All Sea-fliers are divers, but, owing to the thickness of their plumage, some are less capable than others of plunging far beneath the surface. They generally fly over the waves at a certain altitude, disporting themselves in the sunshine should the weather be fine, or battling with the elements during[Pg 176] a storm. While flying, their attention is anxiously bent upon the sea beneath, on the look-out for food, upon which, when discovered, they instantly dart down, some of them with the straightness and rapidity of an arrow, others more leisurely, while some, before they seize their prey, settle down and swim. All are equally rapacious, whether they catch food for themselves or rob other birds of their hard-earned booty, whether they devour living victims or content themselves with feeding, like the Vultures, upon carrion. Whatever the sea presents for their acceptance they greedily swallow. In their mode of breeding these birds very much resemble each other. Their nests are generally placed upon the ground, sometimes in wild mosses and swamps, sometimes on ledges or projections of rocks, and in the holes and excavations of the soil. Occasionally they select precipitous cliffs and mountains, more rarely trees; some lay but one egg, others two, three, or four. All show much attention to their mates and offspring. The young are at once introduced to their future element, where they soon learn to catch their own food.
The TERNS, or SEA SWALLOWS (Sternæ), are a race of middle-sized or small slenderly-built birds. Their beak is of about the same length as the head, hard, straight, or gently arched towards the tip, both in the upper and lower mandible. The feet are feeble, and provided with toes united by a short or deeply-excavated web, and furnished with slightly-curved sharp claws. The wings are long, narrow, and sharp-pointed, the first quill being the longest; the tail, which is of medium length, consists of twelve feathers, and is more or less forked. The thick, soft, close plumage is coloured light blue, black, and white, and varies but little either with the sexes, age, or season of the year. The Terns are very extensively distributed, inhabiting every zone; still they appear to prefer warm and temperate climates to the colder regions, only visiting the latter, indeed, for a short time during the year. The members of this group live both upon the sea and fresh water, and during their wanderings follow the windings of coasts and the courses of rivers; some species prefer flat, bare shores, others resort to localities rich in vegetation, while others, again, delight in the neighbourhood of woods. All are exceedingly active, and from sunset to sunrise are constantly on the wing; their nights are passed on dry land, but they apparently require less repose than any of their kindred. They walk badly, and when on the ground hold their body in a horizontal position, slightly depressed in front, so that the tips of their long sabre-like wings are higher than their head, which is kept in a retracted position. In the water they swim like corks, their little feet being almost incapable of assisting them in that element; on the other hand, their powers of flight are wonderful, and will bear comparison in every respect with those of the Swallow. When not in haste they move their wings with slow wide-spreading strokes, and thus glide onwards through the air in a gently undulating line; but if urged to speed they beat the wind with powerful rapid jerks, and skim along with indescribable velocity. In fine weather they disport themselves almost after the manner of Swallows, sweeping round and round in broad circles, and performing a variety of elegant curves and graceful evolutions; but in a storm their energies seem roused to the utmost, and they may then be seen battling untiringly against the gale. Generally they fly very low over the surface of the water, rising and sinking as the waves heave and fall, till suddenly, with close-shut wings, they dart obliquely into the sea, sinking so deep that they almost disappear, but, immediately rising again, they shake their wings and recommence their devious course over the billows. In this manner they fly over a vast extent of water during the day, but however widely they may wander, return again and again to the same track, and never remove far from the locality whence they started. The disagreeable shrieking cry uttered by these birds varies but little in different species. Although the Terns are very sociable in their intercourse with their own kind, they appear to take but little heed of the rest of their feathered companions, even when, as is often the case, they associate with them in search of food. The diet of the Sea Swallows consists principally of fishes and a variety of creatures met with in the sea, their prey being always taken when on the wing. These birds are strictly monogamous: a few weeks before the commencement of the breeding season they begin to assemble in the vicinity of their meeting-place, returning year after year to the same locality. Such species as inhabit the sea-shore generally select coral-banks, islands, or long spits of bare sand for this purpose, while such as settle inland seek out similar, but less barren spots, in the vicinity of swamps and marshes, the various species usually breeding apart from each other. Such as resort to morasses lay their eggs in a mere depression of the ground. Their unpretending apologies for a nest are sometimes isolated, sometimes so crowded together as literally to cover the ground so thickly, that the brooding birds have all to sit with their heads in one direction, and a man cannot pass between them without crushing the eggs of contiguous nests. Even such species as resort to trees construct nothing in the shape of a nest, but deposit their eggs in chinks of the bark or inequalities of the branches. Most of the Terns lay three eggs, others two, whilst those that breed on trees deposit but one. The male and female brood alternately; during the heat of the day, however, they leave their eggs to be kept warm by the sun. The young are hatched in about a fortnight or three weeks, and make their appearance clad in down; they leave the hollow that has served as a nest on the day of their birth, and run at once down to the water's edge, quite as fast as their parents, by whom they are anxiously and carefully tended.