Louis Figuier

Birds are the spoilt children of nature—the favourites of creation. Their brilliant plumage often assumes the most resplendent colours. They have the happy privilege of moving in space—now fluttering through the air, hunting the insect which flits from flower to flower; now soaring high aloft, and swooping upon the victim it has marked for its prey; now cleaving the atmosphere on rapid wing, and performing journeys of vast extent with great rapidity. Mankind have a profound sympathy with these little winged beings, which charm at once by the elegance of their form, the melody of their song, and the graceful impetuosity of their movements.

Anatomically speaking, birds are connected with the Mammifera by their internal structure. Their skeleton essentially resembles that of the Mammals, the bones being nearly the same, only modified slightly for the purposes of flight.

In birds there is a double circulation. The heart consists of two moieties, or lobes, known as the auricle and ventricle. It is conical in form, and occupies the anterior part of the thorax, its apex passing between the lobes of the liver; but there is little perceptible distinction between auricles and ventricles. Their blood is richer in globules than that of the Mammalia, being more thoroughly permeated by air; the respiratory function is also more energetic, from the same cause—in fact, they consume a larger quantity of oxygen, and produce a proportionately greater degree of heat; for while their lungs are small, and placed in the upper part of the thorax only, where they are confined on each side to a cavity, bounded above by the ribs, and below by an imperfect diaphragm, they are perforated by tubes, which communicate with membranous cells, distributed over the thoracic and abdominal cavities, between the muscles, and beneath the skin,—often in all parts of the body. What distinguishes the bird, in fact, is not the wing; for certain of the Mammalia, as the Bat, and even some fishes, as the Gusard and Exocoetus, can traverse the air by expanding their wings. In birds the diaphragm which arrests the air in the Mammalia is scarcely perceptible, so the external air penetrates into every part of the body by the respiratory tubes, which ramify the whole cellular tissue, the interior of the bones, and even the feathers, and between the muscles. Their bodies, dilated by the air inhaled, lose a proportionate amount of weight; balloon-like, they float in the air, and, from their peculiar forms, they can swim, so to speak, in any direction in the gaseous element.

Fig. 45.—Skeleton of the Swan.

Fig. 46.

Wings alone, then, would fail to support the bird in space. The position renders a double system of breathing necessary. Vital heat in animals is always in proportion to their respiration, for the oxygen of the air, which penetrates every cell and cavity of their bones, feathers, and body, warming and giving increased activity to their circulation, and specific lightness to their bodies, from its rich organisation enables birds to live in the coldest atmospheric regions. In Fig. 46 the respiratory organs of a Pigeon are represented. The trachea, or windpipe, is composed of many bony rings, varying in different species. In the Falcons it is slightly flattened, and tapers in a small degree; but in many genera it presents dilatations and contractions, and in others it is variously curved, two slender muscles, which run along its sides towards the sternum, serving to contract it. In many of the song-birds several pairs of small muscles are attached to the lower larynx where the tube bifurcates, by which they are enabled to control this organ, which is the producer of their note.

Fig. 47.

The trachea carries the air to the lungs in a Pigeon, and separates into two branches in the breast, where it abuts on the aËrial sacs, and on the two lungs (Fig. 47). The air carried by the windpipe acts upon the blood through the thin substance of the cells which constitute the pulmonary tissue, in which it traverses in an infinity of minute vessels, whose thin walls are permeable by the gas.

The lungs are small, and placed in the upper part of the thorax, where they are confined on each side by a cavity bounded above by the ribs and below by an imperfect diaphragm; but they are perforated by tubes which communicate with membranous cells distributed over the thoracic and abdominal cavities, between the muscles, beneath the skin, and in all parts of the body—the air even penetrating many of the bones when the species are peculiarly aËrial in their habits.

The external form of birds is modified so as to be subservient to aËrial progression. The vertebral column, or spine, along the centre of which runs the spinal cord, is divided into three regions—the cervical, dorsal, and sacral regions—terminating in the caudal extremities, the number of vertebrÆ, or pieces, varying much in different genera. The body consists of the dorsal, sacral, and caudal parts of the column; laterally, of the ribs and pelvis; and beneath, of the sternum and the soft parts contained in it. Its anterior part, containing heart, lungs, and liver, is named the thorax; the posterior, the pelvis. The sternum, with the clavicles and scapulÆ, is perhaps the most curiously modified part of the skeleton of birds.

The sternum, then, is a large expanded plate extended over the whole anterior part of the thorax, and even covering more or less what may be considered the abdomen. It varies greatly in different genera; but in all it is more or less four-sided, and convex externally, forming the basis for the powerful muscles by which the wings are moved. These wings serve as arms by which the bird guides itself, ascending or descending according to the impulse given them. "That the anterior form of birds is modified so as to be subservient to the aËrial progression for which these animals are intended," says McGillivray, "is obvious and intelligible. Their bodies are oval, with the more powerful muscles placed on the breast, so that, when the horizontal position is assumed, the centre of gravity comes between the wings, and is kept near the lower part by the weight of the pectoral muscles. The length and flexibility of the neck enable the bird to make the necessary changes in the centre of gravity, while the solidity of the dorsal spine gives advantage to the action of the muscles. The head is terminated by a pointed bill, which aids in cleaving the air; the feet, when short, are drawn up and concealed under the feathers; when long, they are stretched out beneath or behind the tail, which is more or less expanded, and helps to support the body in the air, as well as, by acting in the manner of a rudder, to change its direction, or, by being expanded, to break its descent."

Fig. 48.

The wings of birds are acute or obtuse. The more angular the wing of birds—that is to say, the longer the feathers on the edge of the wing—the more rapidly does it propel itself through the air. The tail consists of a number of feathers, to which are attached a series of small muscles, one for each vertebra, which are capable of depressing and elevating the tail in various degrees; while a series of connections, whose fibres invest the base of the quills, curve round the edge of the tail. Their action is to spread out the tail-feathers, and incline them to the right or left; thus enabling it to perform the part of a helm or rudder as it cleaves the atmosphere.

Besides flight, birds possess other means of locomotion. They are formed for walking or for swimming as well as for flying, according as their habits are aËrial, terrestrial, or aquatic. Their general form, though possessing all the characteristics of the class, is modified and adapted to the kind of life they are intended to lead. Where the skin of a bird is covered with feathers, it is observed that the true skin, or derma, is thin and transparent; while the cuticle is thicker, and even covered with scales, in those parts where feathers are absent.

Before addressing ourselves to the physiological functions of birds, a few words descriptive of their feathers, beaks, and claws will not be out of place.

The covering of birds is known by the general name of plumage. It is composed of many individual feathers. The feathers are horny productions, consisting of a hollow tube or barrel, and a stem rising from it. Chemically, this covering is of the same material as the hair on Mammals and the scales on reptiles and fishes, differing only in its mechanical structure. Besides the more conspicuous feathers, most birds have an underneath covering of smaller ones known as down-feathers. A feather of the ordinary kind consists of the tube, or barrel, by which it is attached to the skin, varying in length according to the species; the stem, or shaft, composed internally of a soft, compact, but elastic substance of a whitish colour, and in its buoyancy not unlike cork; the web, which is a lateral prolongation of the external coating of the shaft, and which assumes the form of a thin linear membrane springing from it at an angle more or less acute in different species: this is the barb. From the upper edge of each barb two sets of minute filaments proceed at an angle similar to that of the barb itself in respect to the shaft. These smaller filaments are the barbules, by means of which the barbs are retained in opposition—not by the barbules of one barb interlocking with those of another in the manner of dovetailing, but by the anterior series of one barb overlapping and hooking into the recurvate formation of the barb next to it (Figs. 51, 52). The barbules themselves frequently throw out filaments in the same manner, which are called barbicels, whose object is apparently the same—namely, that of connecting and retaining the barbules in position. These may be observed, by the aid of a small magnifying glass, in the quills of the Golden Eagle, Aquila chrysaËtus.

Feathers, then, consist of three parts—the tube, the shaft, and the webs; the webs being the barbs furnished with barbules, sometimes barbicels. They are convex above, and are thus enabled to resist flexion or fracture better from beneath than from any other direction. They are also elastic; and this property, together with their curvature, tends to keep them closer together.

In the feathers of a large portion of birds there is a plumiform formation, or small feather or plumule. This plumule is conspicuous in gallinaceous birds—for instance, the Pheasants (Fig. 53); it springs from the fore part of the tube, just at the commencement of the shafts; it gradually narrows, and is continued in the form of a very delicate, thread-like fibre; from its side proceed two series of barbs, and from the barbs two series of barbules, extremely fine, entirely disunited, and very loose. This plumule seldom exists among aquatic birds, but in gallinaceous fowls it attains the length of two-thirds of the feather, and in the Emu and Cassowary it equals it in length.

Feathers may be divided into those specially employed as the means of locomotion and those intended to protect the bird from extreme cold. The former are much stronger, more compact, and more elongated than the others. The row of feathers bordering the wing behind is known as the alar quills, or wing-quills, and those terminating the extremity of the tail, as caudal quills. From the head, backwards to the tail, the feathers increase in strength and size; those on the face, or round the base of the bill, being smallest, the tail-coverts longest. Immediately covering the base of the wing-quills are a row of feathers on both surfaces of the wing; these are the quill-coverts.

The most brilliant feathers are found in birds of warm climates, and the more tropical the climate the more dazzling and brilliant is the plumage. In many species the brilliant plumage is confined to the males, while that of the females is dark and sombre. In other cases it is the same in both sexes. The young of some species attain the adult appearance after the first moult; others take several years to acquire their full splendour.

Birds cast their feathers at least once a year, in order to put on a fresh dress. This is called moulting—a change which usually occurs in the autumn, but sometimes both in spring and autumn. During the moulting season birds are dull, retiring, and silent; but when they emerge from this state they proudly display their lively colours, which now rival the gayest flowers that surround them.

Among the gallinaceous birds, and especially among the aquatic species, there exist over the coccyx certain receptacles from which is distilled the oily substance with which they lubricate their plumage. These receptacles are known as the uropygial glands. On the lower surface is a layer of cellular tissue containing a similar fluid, which seems to be connected with the growth of the feathers.

The beak, or bill, of birds is composed of two bony pieces, called mandibles, surrounded by a horny substance, differing both in form and thickness according to the habits of the species. In the genus Falco the bill is shorter than the head; the upper mandible is furnished at the base with a bare coloured skin, of a peculiar dense texture, called the cere; its outline slightly convex as far as the edge of the cere (Fig. 61), then curved so as to form about the third of a circle, and evidently destined, in connection with its formidable claws, to tear its prey.

In the Toucans RamphastidÆ the bill is half a foot long, hollow within, thin, and nearly transparent; and the mandibles are so disposed as to combine, with their great bulk, strength and lightness, and assisting by their digestive power to assimilate both animal and vegetable food (Fig. 62). In the PelicanidÆ, as in the Common Cormorant, Phalacrocorax carbo, the bill is long, straight, and compound; the upper mandible curved towards the point, the lower compressed; the base inserted in a small membrane which extends under the throat. In the back part of the head is an additional bone (Fig. 63, a), attached in such a manner to the occiput as to admit of great expansion, which permits of its swallowing plaice and other flat fish of considerable size. The Crane, Grus cinerea (Fig. 64), has the bill rather longer than the head, strong, straight, compressed, and pointed at the extremity; the sides of the mandible deeply channelled with nostrils, and closed backwards by a thin membrane.

In the Goose, genus Anser (Fig. 65), we find the bill short, not longer than the head, conical, covered at the base with a cerous skin, with under mandible smaller than the upper. In the Sparrows, Passerina (Fig. 66), the bill is strong and conical, the upper mandible slightly curved, the lower compressed and smaller than the upper; nostrils lateral, basal, round, and partly concealed by the short feathers at the base of the mandibles. In the Goatsuckers, Caprimulgus (Fig. 67), the bill is remarkably small and weak, the sides inflexed and sometimes gaping.

The tongue, like the bill, however, is only an accessory to the digestive apparatus; for while the beak serves the purpose of prehension and trituration, the tongue assists in deglutition or swallowing. Digestion is so active in some birds, that they get fat in an excessively short space of time. The Ortolan Bunting, Emberiza hortulana, and some others, are fattened for the table in five or six days. In the swelling under the throat, called the crop, a (Fig. 68), or first stomach, which is largely developed in some of the granivorous or grain-eating birds, the food remains for a time, where it undergoes certain modifications which facilitate digestion; thence it passes into the succenteric ventricle, or second stomach, b (Fig. 68),—there it imbibes the necessary amount of gastric juice; being finally transformed into chyme in the gizzard, c (Fig. 68), or third stomach, which is possessed of great muscular power, being capable of acting upon the most solid bodies, triturating even the flints and gravel which the gallinaceous birds swallow to aid their digestion.

The organ of sight is, indeed, more highly developed in birds than in any other class of animals. The volume of the eye itself is large compared with the head. It includes an addition which seems to be confined to birds. This is a black membrane, with many folds, very rich in blood-vessels, and situated at the bottom of the ocular globe, and advancing towards the crystalline. Anatomy has failed to explain the use of this, but it is supposed that by advancing or withdrawing it, it gives to birds additional power of vision. Other parts of the eye, such as the choroÏds, the thin membrane which covers the posterior part of the eye, the iris, the retina, present nothing remarkable. The white of the eye is surrounded by an osseous or cartilaginous matter, evidently placed there for protection of this delicate and useful organ.

Besides the ordinary upper and lower pupils, birds possess a third. This consists of an extensive transparent membrane, disposed vertically, which covers the eye like a piece of network, protecting it from the effects of a blaze of light. It is this pupil, or nictating membrane, placed at the internal angle of the eye, between the orb and the external pupil, which the animal uses at will, which permits the Eagle to gaze at the sun, and prevents the nocturnal birds of prey from being dazzled when exposed to daylight.

The perfection of the sight of birds seems to be proved from the Vulture, so distant from his prey as to appear a mere speck in the heavens, without deviation flying directly to it; or the Swallow, which perceives, while on rapid wing, the smallest insect on which it feeds. According to Spallanzani, the Swift has sight so piercing, that it can see only five lines in diameter at the distance of five hundred feet.

Birds, of all animal creation, can traverse distances with the greatest rapidity. The fleetest among the Mammifera cannot run over five or six leagues in an hour. Certain birds easily traverse their twenty leagues in the same interval of time. In less than three minutes we lose sight of a large bird, such as a Kite or an Eagle, whose body is more than a yard from wing to wing. It is assumed, from these facts, that these birds traverse more than fifteen hundred yards each minute, or more than fifty miles in an hour. A Falcon of Henri II. strayed from Fontainebleau in pursuit of a Bustard; it was taken the next day at Malta. Another Falcon, sent from the Canaries to the Duke de Lermes, in Spain, returned from Andalusia to the Peak of Teneriffe in six hours—the flight representing a distance of two hundred and fifty leagues. In short, the whole organisation gives to a bird that remarkable lightness which contributes so much to its velocity. Not to speak of the feathers with which it is covered, its bones are hollow and form large cells, called aËrial sacs, which it is able to fill with air at will, and its sternum is furnished with a bony frame or breast-bone, formed somewhat like the keel of a ship, into which the pectoral muscles are inserted—which, besides being largely developed, in birds of flight possess remarkable contractile properties.

The vocal apparatus in birds, represented in Figs. 70 and 71, is very complicated, and differs from the human larynx and trachea. It consists of a kind of osseous chamber; which, however, is only a swelling in the arterial trachea at the point where it bifurcates and enters the breast to form the bronchial tube. It is this formation, called the lower larynx, which constitutes the organ of song. Five pairs of muscles, attached to the walls of this chamber, stretch or relax the vocal chord, by which means they enlarge or diminish the cavity of the larynx. Whoever has watched any song-bird singing must have noted the swelling and contracting of its throat as it poured out its melody, modifying, in a thousand ways, the tension of the vocal chords and of the larynx, and producing those marvellous modulations whose perfection must always be a subject of astonishment and admiration.

Our landscape would be sad and mute indeed without these graceful inhabitants of the air, which give so much animation to country life and solitary rambles. In the silence of night, when all nature sleeps and life seems suspended, all at once certain notes of harmony rise from under the dense foliage, as if to protest against the universal silence. It is sometimes a plaintive cry, prolonged into a stifled sigh, now a continuous warbling, now a lively song, gay and melodious, which the whole forest re-echoes to.

When the darkness of night gives place to the first dawn of day—when the soft gleam of Aurora has appeared on the horizon, all is transformed, all is vivified on the new-born earth, lately asleep and apparently deserted. The larger birds rise higher and higher in the air, till they are lost in the clouds. The small birds hop from branch to branch with joyous gambols, communicating a movement of happiness and content over all nature. What a wonderful variety of music issues from them—what dazzling brilliancy and variety deck their plumage—what a charm pervades the whole scene, enlivened by these living flowers flitting about in intense enjoyment, hovering, traversing, and embellishing the air! Be it a Titmouse, which seems to spend its life suspended from the branch of a tree; or the Fly Catcher, on the other hand, always perched; the Lark, performing its graceful circles in the air as it rises higher and higher, pouring forth its melodious song more vigorously with each circle described; the Thrush, which runs along the grassy path, watching for its prey, or the House Sparrow chirping from the straw-built roof, or the Robin warbling from some leafless bower—how completely the little winged wanderers decorate the landscape and improve the picture with their innocent gambols!

Assuredly birds have a language which they alone comprehend. When danger threatens them, a particular cry is uttered by one, and immediately all of the same species hide themselves until their fears are dispelled and confidence restored. When the presence of a bird of prey is announced by the plaintive cry of the Thrush, all the feathered race of the neighbourhood are hushed into silence.

Birds of prey with carnivorous instincts live in the most solitary places. The Eagle lives alone with his mate in some unapproachable aerie, his nest placed on the side of some steeply-scarped mountain, or perhaps hidden in the depth of some inaccessible ravine, whence they sally forth to visit some distant region in search of prey.

It is very difficult for us to appreciate the degree of intelligence exhibited by birds. In the Mammifers, whose organisation approaches nearer to that of man, we are enabled partially to comprehend their joys and griefs; but in the case of birds we are reduced to conjecture in order to arrive at an estimate of their sensations. To explain this profound mystery a word has been invented which satisfies easy minds: we call the sentiment which leads birds to perform many admirable actions which are related of them, instinct. The tenderness of the mother for her young—a tenderness so full of delicacy and foresight—is, we say, only the result of instinct. It is agreed on all hands, however, that this instinct singularly resembles the intelligence called reason, and, in the opinion of many, is nothing else.

Reproduction in birds occurs at intervals regulated by nature, and they are distinguished, above all other creatures, for the fidelity of their affections. It is frequently a matter of observation that a male attaches itself to a female, and they henceforth live together till the death of one or both; and many affecting scenes are described where death has overtaken one of the affectionate pair. When the breeding season approaches, the habits of the female are modified; she abandons her former freedom, and, having laid her eggs, she passes her whole time in incubation, defying hunger and all other dangers, apparently well instructed in the fact that the equal and prolonged heat communicated by their contact with her body is necessary to hatch them. During the period of incubation the male, in most instances, watches the female, and supplies her with food; afterwards the little ones are waited on by both the parent birds with the tenderest care until they finally attain the use of their wings.

The solicitude of birds for their young is first manifested in the choice of the locality for the nest, and in the care with which this cradle of their progeny is constructed. But all this disappears when the young no longer require the maternal protection.

In spring, when the birds have paired, they set themselves to work at once to collect the necessary materials for their nest. Each carries its blade of grass or stem of moss. Large birds content themselves with a coarser structure—chips of wood, or branches of trees interlaced with twigs, lined with hair and other soft materials, are fashioned into the necessary shape. But the smaller species really display great art in framing their miniature dwelling, which they furnish inside with wool, blades of grass, or down, the male and female labouring in the common work. Their effort is to make a soft, warm, and solid bed on which to deposit the coming eggs. The mother-bird has recourse to all sorts of cunning devices in order to conceal her nest from prying eyes, choosing for this purpose the heart of a leafy bush, the forked limb, the concealed crack or hollow in the trunk of a tree, the chimneys of a house, crevices in a wall or under a roof. Curiously enough, the nests of the same species are always fashioned in precisely the same manner. The Kinglet, or Wren (Fig. 72), builds its nest under a bank, generally near some brook; it is neatly formed of moss, nearly covered with leaves, and lined with small feathers, hair, and wool. In this nest the smallest of our native birds lays six delicate little white eggs, marked with small pink spots. The Humming-birds (Fig. 73), which flit about in tropical woods, build their nests of grass, lined with feathers. The House Sparrow (Fig. 74) builds its nest under the eave of some house; while the Hedge Sparrow (Fig. 74) chooses the fork of a hawthorn-tree in which to construct its children's home. The Magpie, more ambitious, constructs, in the topmost fork of some tall ash, or poplar, or elm, its nest of branches interlaced with twigs, and lined with fine grass, hair, and other soft materials (Fig. 75). It is a large and consequently a conspicuous fabric, elliptical in form, composed first of rough boughs, on which is laid a quantity of mud, and then a layer of twigs, the whole lined with fibrous roots and other soft material. The Goldfinch builds its nest on trees; it is composed of grass, moss, and lichens, and lined with the down of various plants and such other soft material as comes in its way, elaborately interwoven with wool and hair (Fig. 76).

The Owl, Strix flammea, chooses her nest in some obscure nook of an old tower, the steeple of a church, a dovecot, or the hollow of an aged tree (Fig. 77). It is composed of twigs and straws loosely arranged.

Some birds form into a sort of coarse tissue the fibres of which they construct their nest, which has procured them the name of Weaver Birds. The nest of Fondia erythrops occupies the centre of a bundle of reeds growing in shallow water, in which various grasses are roughly interwoven in the form of a cupola. The Black-headed Synalaxis, S. melanops (Bonaparte), constructs a more delicate fabric, but remarkable for its strength. It builds its nest with grasses, interlacing them in a firm and inextricable web; the form is globular, and the entrance is a small hole in one of its sides. The Orioles and Cassiques of the New World cannot be passed without noticing their wonderful skill in nest construction. The nest of the Baltimore Oriole forms a perfect family pouch, which it suspends from the upper branches of a shrub or tree. The nest of Cassicus hÆmorrhous (Cuvier) consists of dry grasses woven into long sacks, gradually increasing in size towards the bottom, with an elongated slit in the side; this is so constructed as to exclude rain from the nest. These wonderful structures are sometimes two yards in length; and when these birds are numerous in the country, the nests, as they hang suspended from the branches of trees, give a singularly novel aspect to the landscape.

Not less curious is the nest of the Tailor Bird, Orthotonia (Fig. 78), which is formed of a large leaf, the two sides of which the bird has contrived to sew together; in the interior is placed the nest. Miraculous indeed is the produce of these little workers. The wonder is how the birds contrive to enter a nest on the wing when the opening seems scarcely so large as the bird's body, and yet it enters without disturbing a fibre. The hut of some savage races is left constantly open, their intelligence not suggesting a protecting door. The Spiders are more ingenious. They contrive to close the entrance to their dwellings, while the door is left habitually open; some birds adopt analogous precautions. In M. Jeudon's book on the Birds of India, he reports a curious arrangement of a species of Homrain: when the female of this bird begins to lay, the male encloses her in their nest by shutting up the door with a thick mud wall, leaving only a small opening by which the female can breathe and receive her food from the male bird's bill; for this severe husband is not forgetful of his duties, but every few minutes conveys some morsel to the enclosed prisoner.

Sonnerat, in his "Voyage to India," speaks of a Cape Tit, the nest of which is in the form of a bottle, and composed of cotton. While the female hatches the eggs, the male, like a true sentinel, maintains a strict watch on a specially-formed resting-place, built on one of the sides. Finally, for ingenious construction, instigated by affection for its progeny, there is nothing to compare to the work of the Republican (Fig. 79). This little bird of the Cape, which is about the size of a Sparrow, which it much resembles, lives in numerous families, that unite in forming immense colonies. Their dwellings have the appearance of a circular framework surrounding the trunk of some large tree, as represented beneath. Levaillant counted as many as three hundred cells, which indicate that it is inhabited by six hundred birds. These nests are so heavy that Levaillant was compelled to employ a cart with many men in transporting one of their colonies. At a distance they resemble great roofs attached to the trunks or branches of trees, on which hundreds of birds sport and enjoy themselves. Further, the Oriole suspends its basket-like nest by a twig at the extremity of a flexible branch, placing it thus beyond the reach of any prowling four-footed ravisher. The Magpie selects the topmost fork of the loftiest trees. Again, the nest of the esculent Eastern Swallow, the one so much sought after by gourmands, hangs from those cliffs washed by the sea, and is constructed of a fucus, or marine plant, of the genus Gelidium, which gelatinous substance, cemented by the saliva of the bird, forms a sort of paste of most delicate flavour.

When this nest is built, and the walls properly cemented, and the home of the little brood prepared, the eggs are laid and the process of hatching commences. Eggs are generally numerous in inverse proportion to the size of the bird. The Eagle lays two, for instance, while the Titmouse (Parus) lays from twelve to eighteen.

The eggs laid, the female must now submit to the long and painful labour of incubation. While the male lies in wait in the neighbouring bush to defend his young brood against any enemy which may present itself, giving battle to much larger animals if they venture to attack his nest, the female only quits her charge for necessary food, and her place is often occupied during her absence by her mate. Enemies that lie in wait are numerous. Among them may be enumerated birds of prey, small quadrupeds, reptiles which treacherously insinuate themselves into the nest, and perhaps more unfeeling than all, children with destructive instincts.

If nothing occurs to disturb the repose of the pair, the male, perched upon a neighbouring branch, pours out a song expressive of his felicity. The little ones are finally hatched. Helpless and incapable, without feathers and with closed eyes, they are utterly dependent on the parent birds, by which they are fed until the time when they are covered with feathers. They now begin to try their wings, and find their own food. The mother directs their first efforts, uttering a peculiar cry to attract them when she discovers a favourite morsel; defending them courageously, and, with a total abnegation of self, meeting the most formidable enemies; sometimes going so far for their protection as to offer herself a victim. How pitiful are the cries of a Swallow whose nest is built under the roof of a house on fire! Fearlessly she rushes on the flames, flying to the assistance of her young, as if she would rescue them or perish under the fatal roof. Or mark the unhappy Partridge which the sportsman has surprised on the nest. She hesitates not to offer herself a sacrifice, throwing herself almost under the intruder's feet, in order to attract his attention from her progeny.

When the young are strong enough to take wing, they abandon the family tie, and soon lose themselves in the great world of nature, forgetful of their parents' unselfish care. The ingratitude of their first-born does not, however, discourage the forsaken couple. With the returning season they renew their labours, exhibit the same solicitude, the same affection, to meet with the same return. Nature is an unfailing source—an eternal focus of tenderness and love.

Most families of birds are migratory; that is, they abandon their summer quarters and undertake long journeys at certain seasons. These migrations occur with the greatest regularity. By their departure from temperate or cold climates they prognosticate the approach of winter, as their return heralds spring. Among the ancient Greeks, as we learn from a passage of Aristophanes on birds, the arrival of the Crane pointed out the time of sowing; the arrival of the Kite the sheep-shearing season; and the arrival of the Swallow in Greece was the date for putting off summer clothing. The impulse which causes birds to depart is an instinctive desire to find climatic conditions appropriate to their wants of life. At the approach of winter they desert the regions of the north in search of southern countries with a warmer climate, while others migrate northwards to escape the heat.

Nevertheless, all birds are not migratory; many species remain during their whole lives in the locality where they were hatched, straying but little distance from their birth-place. The majority of those which migrate perform their journeys annually and with great regularity; a few irregularly and accidentally; that is, they are caused by necessity, or by atmospheric influences, to change their residence; and it is no unusual sight on such occasions to see numerous flocks of birds assembling under the leadership of a chief, and taking their flight in perfect order, traversing seas, and passing from one continent to another, with astonishing rapidity. On the 22nd of September, 1771, White, of Selborne, witnessed the flight of a flock of Swallows which had rendezvoused the night before in a neighbour's walnut-tree. "At dawn of what was a very foggy day, they arose all together in infinite numbers, occasioning such a rustling from the strokes of their wings against the hazy atmosphere that the sound might be heard at a considerable distance." In the Old World, choosing a time when the winds are favourable, most migratory birds direct their flight towards the south-west in the autumn, and the north-east in spring. In America the migratory birds take a south-east direction in autumn, and the reverse in spring. These aËrial travellers instinctively direct their flight to the same regions—often to the same district; and there are good grounds to believe that the same pair frequently find their way year after year to the same nest.

The duration of the life of birds in a state of nature is one of those subjects on which little is known. Some ancient authors—Hesiod and Pliny, for example—give to the Crow nine times the length of life allotted to man, and to the Raven three times that period; in other words, the Carrion Crow, according to these authors, attains to seven hundred and twenty years, and the Raven two hundred and forty. The Swan, on the same authority, lives two hundred years. This longevity is more than doubtful. Paroquets, however, are known to have reached more than a hundred. Goldfinches, Chaffinches, and Nightingales unquestionably, even in the confinement of a cage, have lived four-and-twenty years. A Heron, Girardin tells us, lived fifty-two years, which was testified by the ring which he bore on one of his legs, and even then he lost his life by an accident, while in full vigour. A couple of Storks, moreover, have been known to nestle in the same place for more than forty years. All that we can affirm is that birds live much longer than the Mammalia.

We can easily fix a circumscribed geographical boundary to any species of Mammalia. They may be limited to a country, or even a district. Can we impose a like distribution on birds? At first sight this seems difficult: their powerful organs of locomotion permit of their travelling rapidly; and, moreover, their nature, essentially mobile, and their wandering humour, lead them to continual change; and then their organisation adapts them for great extremes of temperature—circumstances which would lead us to consider them quite cosmopolite. Nevertheless, many species reside habitually in countries of very limited range. A Sovereign Hand has traced on the surface of the globe limits that cannot be passed. How such small creatures are able to perform such distant journeys, pausing only at far-severed resting-places for necessaries, has always been a matter of surprise. They pass on without an instant's sleep, however long and fatiguing the route. How can the Quail, for instance, with its short wing and plump body, traverse the Mediterranean twice in the year? Hasselquist tells us that small short-winged birds frequently came on board his ship in squally weather, all the way from the Channel to the Levant; and Prince Charles Bonaparte was agreeably surprised by the visit of a party of Swallows to the ship Delaware, in which he was a passenger, when five hundred miles from the coast of Portugal, and four hundred from Africa. Audubon relates a similar occurrence; and numerous instances are recorded in which these fatigued travellers have taken shelter in the first fisherman's boat they met, sometimes so weak as to be hardly able to move a wing. It is therefore a fact truly inexplicable, in spite of every hypothesis, more or less reasonable, which has been advanced by naturalists in explanation.

Men have little influence over birds, and have, therefore, few opportunities of studying their habits in a state of nature. Some few species may be retained in captivity, and some observers have been able to obtain their entire confidence while in that condition; but, except two or three species, it has not been possible to reduce them to a state of domestication. Our knowledge of the habits and manners of the feathered race is, therefore, entirely dependent on chance observation.

The Humming-bird is confined to certain portions of America. The Nightingale, if a visitor to Scotland, is only found in Berwick and Dumfriesshire in fine seasons, while it is constantly seen in Sweden, a country much colder and much more northerly. The Toucans, so brilliant in plumage, are only found in tropical South America. The Swallow, so rapid on the wing, clearing its twenty leagues an hour when it leaves us for its southern winter quarters, never deviates from the route which seems to have been traced for it by a Sovereign Master.

It may, then, be stated that the great zones of the earth differ as much in birds as in the Mammifers found in them. We find in climatic regions birds, or groups of birds, of perfectly distinct species, and which are rarely found beyond that particular zone. Glancing at the various countries forming a region, particular types of birds are easily recognised. Africa, for instance, alone possesses the Great Ostrich, while only a small species exists in America—the Rhea; the Emu represents the genus in Australia. Africa has species brilliant as the most precious stones. To America belong exclusively the Humming-birds, so remarkable for the brilliancy of their plumage. Again, if Africa is the country of the Vulture, to America belongs the Condor.

Nevertheless, the acclimatisation of birds is by no means beyond our power. Experience proves that by carrying a bird far from its native country, and placing it in conditions approaching those to which it has been accustomed, it will live and multiply—acclimate itself, in short, to its new home.

Europe possesses no ornithological type peculiar to it. It is only in Africa and America that we find those rich varieties of form and colour which characterise the feathered race. The Island of Madagascar is the land which possesses the greatest number of ornithological types—simply, perhaps, because that island abounds in species whose rudimentary wings do not permit of their wandering away. Whatever the cause, however, the species found there are not obtained elsewhere. Here we find the unique Dodo, a form of animal which became extinct in Europe in the last century.

There is a wonderful charm of companionship in birds—they give animation to the scene, skipping from bush to bush, or skimming the surface of land and water. They please the eye by their graceful shape and plumage, and they charm our ears by their ceaseless warblings. Even in this sense we lie under a debt of gratitude to these graceful inhabitants of the air. But this is far from being the limit of the benefits we derive from them. The birds of the poultry-yards furnish our most delicate food; their eggs form a considerable branch of trade, and are indispensable in the kitchen; and what would become of our country gentleman should our game birds ever become extinct?—an event by no means improbable, seeing that, in the year of grace 1868, the head-dress of every votary of fashion was decorated with the wing of a bird—not confining the demand to Birds of Paradise, Ostrich, Pheasant, and other feathers of brilliant plumage whose value was a protection, but extending to the harmless sea-fowl, which were destroyed by thousands only for the sake of their feathers.

Birds are useful to man by their feeding on the insects, larvÆ, and caterpillars which infest cultivated crops. Without their aid, agriculture would become impossible. In former times it was a favourite doctrine with the agriculturist that the Passerina were the real destroyers of his crops, and a war of extermination was declared against them; but the observations of more enlightened persons have demonstrated that the chief food of most of these consists of insects, and the havoc among them has consequently been stayed; still much ignorance, and its concomitant, cruelty, exist on this point. Elsewhere, those interested soon discovered that the destruction of small birds led to formidable increase in the numbers of voracious insects—that these lively and joyous creatures, which float in the air and twitter on the bough, are sent us more for good than evil, and that if some of them make the crops pay a tax, they repay it tenfold by keeping down the excess of more destructive ravagers.

While the smaller birds have proved essentially beneficial to man, some of the larger birds exhibit similar tendencies. The Wading Bird clears the earth of serpents and other unclean and venomous animals. The Vultures and Storks throw themselves in flocks on corrupt carrion, and divest the soil of all putrefying objects: thus, in concert with insects, birds are the scavengers of the earth, lending their aid to make it a fit residence for man; in fact, are constituted by nature guardians of the public health.

In former days Falconry afforded a stately and picturesque sport to the great, in which lords and noble dames assisted. This pastime still exists in some parts of England and some portions of the East, especially in Persia, where the Falcon is trained to chase the Gazelle and small ruminants; while in China and Japan the Cormorant and Pelican are taught to fish the rivers for their masters. From very ancient times, the Carrier Pigeon was the bearer of messages now transmitted along the electric wires with lightning speed.

Nor do these benefits comprise all the claims of birds to the gratitude of man. In tropical America the Agami, Trophia crepitans, or Trumpet Bird of Guiana, is domesticated, and so docile in its habits, that it is employed to watch the flocks, which it does with the fidelity and intelligence of a Dog. "The Agami," says M. Monocour, "is not only tamed easily, but becomes attached to its benefactor with all the fondness and fidelity of a Dog. When bred in the house, it loads the master with caresses, and follows all his motions, but is easily offended." It is bold and obstinate, and will attack Cats and Dogs, fighting a tough battle with one of the latter, however considerable his size. In Cayenne the denizens of the poultry-yard are confided to its care; it leads them to their pasture, prevents them from straying to a dangerous distance, and brings them home in the evening, just as a trained shepherd's Dog will do the flocks committed to his care, and it manifests its delight by cries of joy when its master vouchsafes a caress in return for its faithful service. The Kamichi, which belongs, like the Agami, to the same order, possesses similar characteristic intelligence. Like the former, it is sociable and susceptible of education, and becomes a useful auxiliary to the inhabitants of South America.

After these brief remarks on the organisation and habits of birds, we proceed to describe the more remarkable species, arranged according to a simple and comprehensive order of classification, placing before the reader the various orders of the class Aves, in the ascending scale which has been adopted in our previous works.

Aves—Birds.

Warm-blooded, vertebrated, biped animals. Pectoral limbs, fore-arms or wings organised for flight; feathery integument; red blood; respiration and circulation double; lungs fixed and perforated.

I. Natatores, or Palmipedes.

Swimming birds, having the toes united by a membrane; legs placed behind the equilibrium; the body covered with a thick coat of down beneath the feathers. They include the following orders and families:—

I. Brevipennes, Ostriches, Cassowaries, the Penguins, Auks, Guillemots, and Grebes.

II. Longipennes, including the Terns, Gulls, Mews, Petrel, and Albatross.

III. Totipalmates, the Pelicans, Gannets, Cormorants, Frigate Bird, Tropic Bird.

IV. Lamellirostres, the Ducks, Geese, Swans, Flamingos.

II. Grallatores.

Wading birds, having the legs long and naked from the tibia downwards.

I. Macrodactyli, Crakes, Coots, Rails, Screamers.

II. Cultrirostres, Boatbills, Cranes, Herons, Ibis, Storks, Spoonbills.

III. Longirostres, Avocets, Snipes, Ruffs, Turnstones, Sandpipers, Godwit, Curlews, Gambets.

IV. Pressirostres, Oyster Catchers, Thicknee Plovers, Lapwings, Bustards, Coursers.

III. Rasores.

Scratching birds. Feet with strong, obtuse, scratching claws; mandible vaulted; nostrils pierced at the base, covered by a cartilaginous scale.

I. GallinaceÆ (Polygamous), Pea-fowl, Partridge, Pheasant, Quail, Grouse, Pentados, Turkey, Curassow.

II. ColumbaceÆ (Monogamous), Pigeons, Gouravinago.

IV. Cantores.

Singing birds. Legs short and slender, three toes before and one behind. In this order, according to Professor Owen, the brain attains its greatest proportionate size, and the organs of the voice their greatest complexity.

I. Dentirostres, Shrikes, Wrens, Wagtails, Thrushes, Warblers, Manakins.

II. Conirostres, Birds of Paradise, Crows, Tits, Starlings, Buntings, Larks, Finches, Grosbeaks.

III. Tenuirostres, Nuthatch, Creeper, Sunboard.

IV. Fissirostres, Swallows, Martins.

V. Volitores.

Birds moving solely by flight. Skeleton light and buoyant; head large; keel deep (entire on the Humming-bird); wings powerful, in some long and pointed; legs small and weak. The order includes—

I. CypselidÆ, Swifts.

II. TrochilidÆ, Humming-birds.

III. CaprimulgidÆ, Night-jar.

IV. TrogonidÆ, Trogons.

V. PrionitidÆ, Momots or Motmots.

VI. MeropidÆ, Bee-eaters.

VII. GalbulidÆ, Jacmar.

VIII. CoraciadÆ, Rollers.

IX. CapitonidÆ, Puff-bird.

X. AlcedinidÆ, King-fishers.

XI. BucerotidÆ, Hornbills.

VI. Scansores.

Climbing birds, with opposing toes in pairs, two behind and two before. The order includes—

I. RamphastidÆ, Toucans.

II. BucconidÆ, Barbets.

III. CuculidÆ, Cuckoos.

IV. PicidÆ, Woodpeckers.

V. MusophagidÆ, Plantain-eaters.

VI. ColiidÆ, Colys.

VII. PsittacidÆ, Parrots.

VII. Raptores.

Rapacious birds, with strong, curved, pointed, and sharp-edged beak; legs short and robust, three toes before and one behind, armed with strong, crooked talons. The order includes—

I. Nocturnes, Owls.

II. Diurnes, Eagles, Vultures, Hawks.