Alfred Edmund Brehm

We were some time ago both delighted and astonished by the performances of a German artist, who imitated with wonderful exactness the notes of a variety of birds. The song of the nightingale and the warblings of the skylark, the whistling of the throstle and the out-poured melody of the canary, were gone through with such perfect execution, that the birds themselves, we thought, could scarcely have detected a flaw in the performance. This gifted individual introduced himself to his audience by a somewhat humorous account of the manner in which he had acquired his extraordinary powers. He told us that his father, who was a breeder of birds, had upon one occasion gone from home, leaving a bag of rice as provision for his children, and a quantity of bird-seed for his feathered protÉgÉs. By some mistake the rice had been given to the birds, and the bird-seed to the children, the consequence being, that on the gentleman's return he found his birds all dead, and his children singing like piping bullfinches. How far this explanation was satisfactory we will not stop to inquire; but we have sometimes been almost tempted to suppose that some similar accident must be of frequent occurrence in Germany. The deep acquaintance of the ornithologists of that country with the objects of their study, and the fidelity with which they note down the minutest incidents connected with the history of their favourites, surpassing anything achieved by other naturalists, not even excepting such enthusiastic labourers as Wilson and Audubon, demands our warmest praise; while the patient industry, so conspicuous in their writings, at once calls for and excites our admiration.

Among the foremost of his countrymen in the cultivation of ornithological research stands the author of the magnificent work whose pages it is our wish to lay before English readers. Not content with studying the natural history of his favourites from books, or even in the rich scientifically arranged collections contained in so many Continental museums, his zeal led him to follow them even into their own wild retreats, and, gun in hand, to penetrate the burning deserts of Eastern Africa, and the equally inhospitable, and then but little known, regions of Abyssinia. By thus familiarising himself with the habits of birds in their native haunts, and amid the scenery whereby they are surrounded in a state of nature, he has been enabled to impart a freshness to his descriptions as characteristic of the real naturalist as the smell of new-made hay is redolent of fields and hedgerows, and no more to be imitated by the mere compiler than the voice of an orator by the reporter of his speeches.

Before, however, we permit our author to speak for himself, it may perhaps be desirable to preface his remarks by a few general observations concerning the structure of the beautiful creatures that form the subjects of his teaching, inasmuch as it is obviously desirable to have clear notions concerning the machinery employed before its adaptation to its intended uses can be made manifest; and further, because in the study of ornithology, as in every other branch of natural history, there are certain conventional terms that may require explanation before the words used in describing an object are intelligible to the uninitiated.

The Bird is an inhabitant of the air in the fullest sense of the expression. The atmosphere is emphatically the sphere of its activity; it mounts it as it would a ladder; it sails through it in triumph, and rides upon the winds as upon a fleet steed. Moreover, it is the atmosphere itself which endows the feathered Ariel with such capabilities, and it is in the perfection of his respiration that we must search for an explanation of his wonderful achievements.

Fig. 1.—RESPIRATORY APPARATUS OF A FOWL.

a, the Lungs, immovably fixed; c, d, the Breast-bone, moving as upon a hinge at b, so that it can be raised to the position indicated by dotted lines at h. 1, 2, 3, 4, 5, 6, Cells, with membranous walls, into which the air is freely admitted during the act of inspiration.

The muscular activity of every animal is intimately dependent upon the efficiency of its breathing apparatus, upon the freedom with which the vital element finds admission to the blood which it is destined to renovate, and upon which it confers those qualities so inseparably connected with the elimination of increased temperature, and the vigour of muscular action. In this respect, as we shall see immediately, the feathered races surpass all living creatures, with the exception, perhaps, of the members of the insect creation.

The lungs of a bird are not suspended, like those of a quadruped, within a circumscribed chest or thoracic cavity, in such a manner as to become inflated by each inspiration; they are rather to be described as soft, porous, and highly vascular organs, through which the air passes as through the interior of a sponge. The movements of the chest, upon which depend the inspiration and expiration of the atmospheric fluid, may be compared to those of a bellows continually employed in taking in and expelling the surrounding element by a mechanism represented in the accompanying figure (Fig. 1). The framework of the chest, consisting of the ribs and of the breast-bone, is so put together that at each inspiration it can be raised, as shown in the drawing, from the position d to the position h, thus materially enlarging the thoracic chamber, just as the upper board of an ordinary bellows is raised for the purpose of taking in the air; but, in this case, the surrounding element, instead of entering through a valve-defended orifice, rushes down the windpipe, and through the immovable, sponge-like lungs, permeating the wide passages with which they are perforated, and not only filling the entire thorax, but penetrating into the interior of the very bones, which are left marrowless for its reception.

The mechanism whereby expiration is effected is equally simple; just as, when the upper board of the bellows is depressed, the air is forced out through the nozzle, so, by the return of the breast-bone to its former position, the inspired air is again forced to pass through the lungs and make its escape by means of the windpipe. By this process it is obvious that the vital element—the oxygen of the atmosphere—being admitted to every part of the system, the blood is vitalised to the greatest possible extent, its temperature is raised until the heat of the body of a bird is far greater than that of an ordinary quadruped, and its vitality is proportionately exalted. Consequently, as the blood circulates through the system, it carries with it heat and life in superabundance; the energies of the entire system are roused to the uttermost; the fibres of every muscle quiver with intense life, like a steam-engine working under high pressure, thus enabling the falcon to cleave the skies with the velocity of a falling thunderbolt, and not only qualifying the swallow for its rapid flight, but enabling it to achieve its wonderful migrations.

This admission of air into every part of the system serves not only to fan the vital flame, and rouse the energies of the bird to an extraordinary degree of tension; it likewise assists in giving buoyancy to its movements, bearing it upward, as the gas does a balloon; for it is evident that the air received into the body being raised to a temperature corresponding to the heat of its blood, the specific gravity of the bird is proportionately diminished, and it rises into the air almost without an effort, and even hovers in the sky with scarcely a perceptible movement of its wings.

A knowledge of the mechanism of their mode of respiration will likewise enable us to explain another remarkable feature in the history of the feathered tribes, namely, their power of song. Who that has listened to the prolonged warblings of a linnet, the flood of melody poured forth from the little throat of the canary, the "lengthened sweetness long drawn out" which almost pains the enraptured ear as we listen to the song of the nightingale, but has wondered how such tiny birds can ever find sufficient breath for the utterance of such long-sustained, such interminable notes? What would our prima-donnas at the opera give for but the tithe of the capacity of these favoured little songsters? No human breast could ever hold sufficient breath for such performances. We now see, however, that the vocal organs of a bird are exactly adapted to the nature of their music. Their whole body is a bellows, as large in proportion to their size as the bellows of an organ is in relation to the pipes into which it has to pour the sound. The little bird is, in fact, a living harmonium—its singing apparatus is not situated at the top of its throat, but is implanted in the inferior termination of its windpipe; and just as the tongue of the harmonium is thrown into vibration by the issuing current of air caused by pressure upon the bellows, so are the vocal chords of the feathered songster rendered sonorous as the air passes over them. In proportion to the capacity of the bellows must be the duration of the note, and we have already seen that the air-cells of the bird are capable of furnishing a supply not easily exhausted. There is, however, this remarkable difference between the two instruments: the tongue of each key of the harmonium can give utterance but to one sound—one never-varying tone—while the corresponding part of the bird, rendered more or less tense by muscles provided for the purpose, contains within itself a whole gamut, and there is not a note in the scale that is not instantly at the command of the inimitable little musician. In the perching birds, among which are found by far the most accomplished singers, five pairs of muscles are connected with this exquisitely-contrived apparatus, and are so disposed as to influence both the diameter and the length of the air-passages. In the parrots three pairs are met with; some of the swimming birds have two, while others have only one; and in a few—as the king of the vultures and the condor—vocal muscles are quite wanting.

Seeing that the temperature of birds is raised so much above the usual standard by the arrangements described above, some clothing is requisite, adequate to retain the vital heat. Another indispensable provision is therefore met with in the Feathers with which all birds are so warmly clad. Indeed, so peculiar is the texture of these admirable fabrics, that no better distinctive appellation could be devised for the entire class than that of the "feathered tribes," by which they are frequently designated. A feather realises in its structure more qualities than imagination could have conceived it possible to combine—lightness, thickness, warmth, durability, elasticity, softness, strength, and beauty. It is one of the master-works of creation. Whoever has examined a feather under the microscope will testify to the incomparable perfection of the contrivance. Every feather is a mechanical wonder. If we look at the quill-portion, or barrel, we find it possessed of attributes not easily brought together—strength and lightness. If we cast our eye upon the upper part of the stem, we see a material made for the purpose, which is used in no other class of animals, and in no other part of birds—tough, light, pliant, elastic—the pith. This is also a substance sui generis; it is neither bone, flesh, membrane, nor horn.

But the most wonderfully constructed part of a feather is the plume, or, as it is sometimes called, the web. This is affixed to each side of the stem, and constitutes the broad expansion of the feather, that part which we usually strip off when making a pen. One of the first things to be remarked is that the web is much stronger when pressed in a direction perpendicular to the flat plane of the plume than when rubbed either up or down in the direction of the stem; the reason of this is that the web is composed of numerous flat, thin, and broad laminÆ, arranged with their flat sides together, so that, although they easily bend towards each other, they offer great resistance in the direction in which they have to encounter the impulse and pressure of the air; and it is in this direction only that their strength is wanted and put to the test.

Another particularity is still more admirable. Whoever examines a feather cannot help noticing that the laminÆ of which we have been speaking, in their natural state seem to be fastened together. Their adhesion to each other is manifestly something more than mere apposition; they are not to be separated without a certain degree of force, and, as there is evidently no glutinous cohesion between them, it is plain that by some mechanical means or other they catch or clasp among themselves, thereby giving to the web its closeness and compactness of texture. Nor is this all. When two laminÆ which have been separated by accident or design are brought together again, they immediately reclasp; the connection, whatever it was, is perfectly restored, and the web of the feather becomes as smooth and firm as if nothing had happened to it. Draw your finger down the feather, which is, so to speak, against the grain, and you will probably destroy the junction between some of the contiguous laminÆ; draw your finger up the feather in the opposite direction, and you restore all to their former state of coherence. This is no common contrivance. Let us now inquire concerning the mechanism whereby it is effected. The laminÆ above mentioned, examined individually, are found to be provided with vast numbers of long fibres, or teeth, which project from their edges in such a manner that, when placed in contact, those of contiguous laminÆ hook and grapple together. The fibres are extremely minute; indeed, fifty of them have been counted by means of the microscope in the space of the 1/20th of an inch. Every fibre is crooked, but bent after a definite manner; those that proceed from one edge of a lamina are long, flexible, and bent downwards, whereas those that proceed from the opposite edge are shorter, firmer, and turned upwards. The manner in which they are united is, therefore, as follows: When two contiguous laminÆ are pressed together, so that the long fibres are forced far enough over the short ones, their crooked parts fall into the angles formed by the crooked parts of the others, just as the latch of a door falls into the cavity of the catch fixed to the door-post, and there hooking itself, fastens the door. This admirable structure, which may be readily seen with a very ordinary microscope, ensures not only the union of the laminÆ, but renders it possible that when any two of them have been separated by violence they will become re-connected with facility and expedition. In the ostrich, this apparatus of crotchets and fibres, of hooks and eyes, is wanting; the filamentary laminÆ hang loose and separate, forming a kind of down; but such a plan of construction, however it may fit the plumes for the flowing honours of a lady's head-dress, must be considered as detrimental to the bird, inasmuch as wings composed of such feathers, although they may assist in running, will not serve for flight.

The power of inflating their whole body with air, and the possession of feathers, are therefore the most distinctive endowments of a bird, inasmuch as these attributes are quite peculiar to the class.

To creatures thus gifted with strength and activity so extraordinary, it is manifest that perceptions of great acuteness are requisite, corresponding with the rapidity of their movements and the intelligence necessary for the performance of the important duties entrusted to their charge; and in this respect, as will be made manifest by a perusal of their history, they occupy a position in the economy of nature fully equal or even superior to that enjoyed by the most favoured quadrupeds. The mental faculties of the parrots correspond with those of the monkeys, whom in their habits and capabilities these birds closely resemble; in cunning they are quite upon a par with their four-handed neighbours, with which, in the forests of tropical countries, they are so generally associated; and when removed from their native woods, and made, as they often are, the companions of mankind, the facility with which they can be taught to imitate human actions—nay, to mimic our very speech—bears ample testimony to the exalted character of their mental capacities.

On examining the brain of a bird, the anatomist is therefore by no means surprised to find that, both in its development and in the perfection of its structure, it surpasses that of many quadrupeds. The proportionate volume of the brain of some of our singing birds, as compared with the dimensions of their body, is astonishing, and reveals to us at a glance the reason why these little favourites are so sagacious and so eminently susceptible of education. (See Fig. 4.)

In strict correspondence with this exalted condition of their cerebral organisation are the senses whereby they hold intercourse with surrounding nature. Their power of vision is beyond our comprehension, and the elaborate contrivances whereby the eye of a bird is adapted to its peculiar mode of life, might furnish materials for a lengthy treatise, imperfect as is our knowledge of the numerous delicate arrangements demonstrable by anatomical skill in every part of its structure. At present we can but briefly allude to a few of the more conspicuous peculiarities wherein the visual apparatus of a bird differs from that of other creatures.

The distances from which the vulture and the hawk can see their prey are almost incredible. To have the "eye of a hawk," to see with "eagle glance," are expressions which, though common enough, give but a very feeble idea of the extent to which those birds are gifted in this respect, or of the vast expanse bounded by their horizon. The falcon sees its diminutive prey from an altitude at which it is itself invisible, and from the very sky swoops down upon its quarry with the velocity of a shot, rarely missing its victim, and thus proving at once the perfection of its sight and the steadiness of its aim. The eye of these birds must therefore be constructed after the plan of a telescope, and its focus adapted to long-sightedness. Its axis must be lengthened to an extent greater than is compatible with a spherical form of the eye-ball. To meet this requirement a circlet of bony plates, constituting a firm but at the same time somewhat flexible ring or hoop, is introduced into the composition of the outer coat of the eye, whereby the requisite elongation is effected, and the organ is thus adapted for perfect vision at a great distance. (See Fig. 4.)

The above beautiful arrangement, however, constitutes but a part of the mechanism required. A telescope adjusted for distant vision is quite useless when brought to bear upon an object close at hand, and its focus must necessarily be altered in accordance with the changed conditions. In the case of the telescope, the needful adjustment would be effected by shortening or lengthening the sliding tube; but in the bird some other plan is evidently indispensable, and few contrivances in animal mechanics are more admirable than that which is adopted. Embedded in the transparent vitreous humour of the eye is a peculiar apparatus called the "marsupium," the texture of which resembles that of the human iris. Now the iris, as we all know, being eminently sensitive to the intensity of light, by its spontaneous contractions and dilatations is enabled to alter the diameter of the pupil of the eye, and thus exactly control the quantity of light admitted. The marsupium, equally sensitive, and equally spontaneous in its action, swells or contracts its dimensions, filling or emptying itself like a sponge, and thus adjusting the lenses of the eye so as to secure perfect vision at whatever distance the object to be seen may be placed. The quickness of sight with which birds are gifted is equally remarkable. The swallow is proverbially one of the swiftest flyers in the feathered creation, and yet in the full career of its flight it is looking on the right hand and on the left, upwards and downwards, for its food. The insects upon which it preys are often exceedingly minute, sometimes flying above and sometimes below the level of the swallow's course, and yet they are seen and captured without any diminution of the prodigious rate at which the bird is flying. Nay, more, any one who attentively watches one of these birds skimming over a meadow, may perceive that it will capture two or even three insects in such quick succession as to convince him that the swallow must have "had an eye upon them" all at once, and yet they are caught, as it were, in a moment.

Another admirable contrivance peculiar to the feathered race, is the existence of a thin, semi-transparent veil, which, when requisite, can be instantaneously drawn over the front of the eye. This apparatus, generally known as the "nictitating membrane," is useful for a variety of purposes; it sweeps over the eye to cleanse it from dust, it diffuses the tears which keep it bright and polished, it will act as a screen to shut out the too great intensity of light, so that with its assistance the eagle can confront the sun even at noon-day; it will likewise defend the eye from sudden injuries, and yet, even when drawn like a curtain over the pupil, not shut out the light. The commodious manner in which this membrane lies folded up in the inner corner of the eye, and the quickness with which it executes its purpose, are known to every observer; but what is equally admirable, though not quite so obvious, is the employment of two kinds of material, and the combination of two kinds of force, by which the movements of this membrane are effected. It is not, as in ordinary cases, by the action of two antagonist muscles, the one pulling it forward and the other backward, but the membrane itself, being elastic, is capable of being drawn out like a thin sheet of india-rubber, and of returning to its former position when the force acting upon it is removed. Such being its nature, in order to adapt it for its office it is connected by a tendon with a muscle situated at the back part of the eye. This tendon, though strong, is so fine as not to obstruct the sight, even when it passes across the pupil, and the muscle which moves it being situated deeply within the orbit, derives from its situation the advantage of not only being secure from injury, but of being out of the way, which it hardly would have been in any position that could be assigned to it in the front of the eye, where its function really lies. When this muscle contracts, the membrane, by means of the communicating tendon, is instantly drawn, as it were, by a thread, over the transparent cornea, and when the muscle ceases to act, the elasticity of the membrane is sufficient to bring it back into its former position. (See Fig. 6.)

But this is not all. In the arrangement of the muscle which, though placed behind the eye, draws the nictitating membrane in front of it, there is what justly deserves to be called a marvellous piece of mechanical contrivance. The extent of contraction necessary to draw the membrane over the whole front of the visual organ would require a much longer muscle than could have been placed in such a situation; in order to meet this difficulty, the tendon which draws forth the nictitating membrane is made to pass through a loop in another muscle, as represented in the next wood-cut (Fig. 7), where it is evident that, by the simultaneous contraction of both these muscles, the extent of their action when drawing the nictitating membrane over the eye is considerably increased. Neither is this the only advantage derived from so ingenious a contrivance; were it not for the plan adopted, the tendon of the muscle u x would press upon the optic nerve, and thus materially interfere with vision—an inconvenience that by the existing arrangement is totally prevented. Devices like these, whereby special machinery is introduced for special purposes, speak for themselves; we acknowledge their beauty, and in them we recognise at once the wisdom and the goodness of the Creator.

The SENSE OF SMELL in birds has afforded subject-matter for much discussion, and great obscurity still exists with reference to the extent to which they make use of their olfactory organs. It has been generally asserted that birds of prey are gifted with an acute perception of odours, and are thus enabled to discover their food at a distance; but the rapidity with which vultures are known to assemble round the carcase of an animal too recently killed to attract them by putrefactive exhalations, has induced many observers to consider them as being directed entirely by sight. That this latter is the preferable theory appears to be sufficiently established by the experiments of Audubon, which go to show that these birds possess a sense of smell very far inferior to that conferred upon carnivorous quadrupeds, and that, so far from guiding them to their prey from a distance, it affords them no indication of its presence even when close at hand.

Having procured the skin of a deer, M. Audubon stuffed it full of hay, and after the whole had become perfectly dry and hard, he placed it in the middle of an open field, laying it down on its back in the attitude of a dead animal. In the course of a few minutes he perceived a vulture flying towards and alighting near it. Quite unsuspicious of the deception, the bird immediately proceeded to attack the carcase, as usual, in the most vulnerable points. Failing in this, he next, with much exertion, tore open the seams with which the skin had been stitched, and appeared earnestly intent upon getting at the flesh which he expected to find within, and of the absence of which not one of his senses was able to inform him. Finding that his efforts, which were long reiterated, led to no other result than the pulling out of sundry quantities of hay, he at length, though with evident reluctance, gave up the attempt, and took flight in pursuit of other game.

Another experiment, the converse of the preceding, was then tried:—A large dead hog was concealed in a narrow and winding ravine, about twenty feet deeper than the level of the ground around it, and filled with briars and high cane. This was done in the month of July, in a tropical climate, where putrefaction takes place with great rapidity; yet, although many vultures were seen sailing in all directions over the spot where the putrid carcase was lying covered only with twigs of cane and light underwood, none of them appeared at all to suspect its presence.

Nevertheless, notwithstanding the apparently decisive result of the above experiments, anatomy teaches us that the olfactory apparatus in this class of animals is largely developed, and indicates by its extent that it is well adapted to investigate the odorous properties of the air taken in for respiration.

The SENSE OF HEARING in birds is remarkably acute, as might be readily inferred from the vocal capabilities conferred upon many of these gifted songsters. Their music is certainly not less appreciated by the performers than it is by their auditors. "Nobody can doubt," observes Bishop Stanley, "who sees a bird singing, clapping its little wings, turning from side to side, and glancing its bright eyes in all directions, as if courting attention and admiration, that it feels delight and satisfaction. Did we require further proof, we have but to recollect that the song-bird is most alert with the music of its voice when its affections and interests are awakened by its mate during the time of rearing its young." It is, indeed, principally during the breeding-season that the singing power of birds is in full activity; and seeing that in general it is only the male that possesses the musical faculty, we may naturally suppose that its exercise is intended for the solace and amusement of his mate during her confinement to her nest. The nightingale himself becomes voiceless so soon as the appearance of his nestlings calls him to more profitable employment.

It is, however, among the nocturnal birds that the faculty of hearing is more specially developed. In the generality of birds there is no provision made externally for catching or concentrating sonorous impressions; but in the owls, the bustards, and a few others that venture forth at night, we find a different arrangement. In the owls, more especially, an external auditory apparatus is very conspicuous; not only does the integument exhibit a variety of folds, the disposition of which forcibly reminds us of the human ear, but the feathers upon the sides of the head are so disposed as to fulfil in some degree the purposes of a hearing trumpet. (See Fig. 8.) In such species the sense of hearing is exquisitely developed.

In the generality of birds the SENSE OF TASTE can scarcely be said to exist. The manner in which they obtain and swallow their food precludes the possibility of enjoyment from this source, so that their tongue is in many cases appropriated to some totally different use. In by far the greater number the tongue is small, thin, and cartilaginous; the extremity is flat, and incapable of being protruded beyond the bill. (See Fig. 9.) There are, however, great varieties in the construction of this organ, a few of which will require our notice.

The tongue of the parrot, although its substance is not so fleshy, has some resemblance to that of man, and it is probable that this is one of the circumstances enabling these birds to imitate the human voice with so much facility.

In the family of the toucans and some others, the tongue, without being extensible, is fully as long as the largely developed bill, and, moreover, its sides are fringed like those of a feather. A tongue of this description may probably be endowed with some delicacy of taste, enabling these birds to appreciate the flavour of the fruits on which they feed.

Birds of the duck family have the largest tongues. Owing to its fleshy appearance it more nearly resembles the human tongue than even that of the parrot. Birds of this family discriminate their food not by sight, but by the delicate sense of touch with which their tongue is endowed. They thrust their bill into the mud, and from the mouthful thus obtained select, by means of their tongue alone, whatever is fit for food, rejecting the rest.

The smallest tongues are found in the night-jars and swallows, two groups which at the same time are distinguished by having the largest mouths in proportion to the size of their bodies; and in this case the design is equally apparent. These birds feed upon living insects captured during their rapid flight, and immediately swallowed whole; taste is out of the question. A large tongue would only be in the way, and it is therefore reduced to a mere rudiment.

In the preceding examples the length of the tongue never exceeds that of the bill; but in the case of the woodpeckers it is protrusible to a wonderful extent. On opening the bill of a woodpecker immediately after it has been killed, the tongue seems of ordinary length, or indeed rather short, and shaped somewhat like the spears used by the Caffres in South Africa, called assagais, pointed at the end and furnished with numerous barbs. (See Fig. 10.) This, however, is only the tip of a very remarkable instrument. If the barbed portion be drawn out of the mouth, a person unacquainted with its nature would think that he had got hold of a very long earthworm that the bird had incautiously tried to swallow, but which had stuck in its throat; hence a tongue of this description is called vermiform. The point in its usual position reposes in the ordinary manner between the mandibles; the rest is concealed, but is susceptible of extension, at the pleasure of the bird, to four or five times the length of the bill. The act of protrusion is effected by the remarkable structure of the root of the tongue, or more properly of the os hyoides, or bony apparatus whereby it is attached. The posterior prolongations derived from the os hyoides are compactly curved around the back of the skull; and occasionally they are prolonged forwards to such an extent as actually to reach the nostrils. By means of this somewhat complex arrangement the woodpecker, having broken away the bark of a tree by the powerful strokes of its bill, and thus laid open the retreat of the insects beneath, suddenly darts out its tongue, spears its prey, and instantly brings the transfixed insect into its mouth.

The SENSE OF TOUCH must be of very limited utility; indeed, there seems to be no part of the body of a bird so constructed as to be capable of tactile impressions. The wings, the representatives of hands and arms, are obviously entirely unfit for the exercise of such a function; neither do the legs and feet seem to be better suited to this purpose. The only organ of touch about which there can be no doubt is the bill, yet even this is generally covered with a hard sheath of horn. Nevertheless, in some races the extremity of the bill is soft and largely supplied with nerves. In snipes and wood-cocks, for example, the sensitive extremity of the beak materially assists in procuring their food.

For the systematic arrangement of the class of birds, the conformation of their feet has been found to afford characters of great importance to the ornithologist, inasmuch as the organisation of these members must obviously be in strict relation with the localities they inhabit. To account for the distribution of the feathered tribes, and to explain the relationships that exist between them and other animals, a great variety of ingenious theories have been broached, all of them more or less fanciful. The different families, sub-families, and minor groups into which they have been divided have been again and again sorted, like a pack of cards, frequently more in accordance with the whim of the player than with the established rules of the game. And yet a little reflection will show that the great principles of zoological classification are so simple, and at the same time so immutable, that we sometimes cannot but admire the ingenuity displayed in going wrong.

Few things are more manifest to the student of nature than that, in the distribution of the animal creation, it has been ordained that every locality shall be peopled by forms of life pre-eminently adapted for its occupation. If, therefore, we are asked whether birds ought to be arranged in circles or in squares, in hexagons or in pentagons, in groups of five or in groups of seven, our simple reply would be by inquiring how many localities could be pointed out as requiring appropriate occupants, and to this question it is not difficult to find a satisfactory answer.

The earth, the water, and the air, throughout their broad domains, must each of them be provided with inhabitants peculiarly constructed to live in their diversified regions. Upon the earth, we find the level ground, the mountain, and the glen; we find the pathless forests, and the solitary trees and shrubs, and bushy underwood. We cast our eyes upon the waters, and we see the world of ocean covering two-third parts of this great globe, stretching from pole to pole, rolling its mighty waves through every zone; we see the creeks and shallow bays that margin it all round, and watch the waves as they approach the shore and lay them down to sleep upon the beach. There are the rivers, too, and lakes, and swamps and marshes which are neither land nor water, sometimes overspread with floating vegetation, sometimes a broad expanse of ooze and rushes far too soft to bear the weight of creatures that might try to walk upon the treacherous surface. We look into the air, and there we find between the earth and sky abundant room for birds of every wing. If, therefore, with this little map of the world before us, we reply to the question propounded above, we should be tempted to say that there must necessarily be as many different types of organisation as there are districts therein enumerated; and doubtless a reference to any system of ornithology, however much the classification may be confused by preconceived theories, will convince us that such is essentially the foundation of any natural arrangement.

In taking, therefore, a brief survey of the principal groups, or Orders, under which the feathered races have been distributed, we will begin with those appointed to live on trees, inasmuch as these are regarded by the author of the following pages as being entitled to the highest rank in the class to which they belong, rivalling in intelligence, as some of them do, the apes and monkeys of which they are in general the inseparable companions.

Few people in this country have any adequate conception of a tropical forest, and, consequently, are scarcely prepared to see whole races of animals constructed specially for a residence in the umbrageous wilderness within its pathless precincts. The great forest of the Amazon, in all its primeval grandeur, stretches for a thousand miles from north to south, and probably three or four hundred from east to west, and over all this vast extent of territory, so closely are the branches interwoven that, as we are told, a monkey might make his way passing from tree to tree without ever coming to the ground except at those points where the rivers hold their course through the tangled yet sublime scenery. "In these untrodden vastnesses the trees, rising frequently to a height of sixty or eighty feet, with stems perfectly straight and without a branch, give support to the huge creepers that climb around their trunks like immense serpents waiting for their prey, or sometimes stretching obliquely from their summits like the stays of a lofty mast, here twisting round each other till they form living cables, as if to bind securely the patriarchs of the forest; there wreathed in tangled festoons, and themselves covered with smaller creepers and parasitic plants." Such is Mr. Wallace's description of the interior of the Amazonian forest.

"The forests of Rio Janeiro," says Mr. Darwin, "are ornamented with the cabbage palm trees 110 feet high, with a stem so narrow that it might be clasped with two hands. The woody creepers themselves are of great thickness, some of them measuring two feet in circumference. If the eye was turned from the world of foliage above to the ground beneath, it was attracted by the extreme elegance of the leaves of the ferns and mimosÆ (sensitive plants). The latter in some parts covered the ground; in walking across these thick beds, a broad track was marked by the change of colour produced by the drooping of their sensitive leaves. It is easy to specify the individual objects of admiration in these grand scenes, but it is not possible to give an adequate idea of the higher feelings of wonder, astonishment, and devotion, which fill and elevate the mind."

These are the localities amongst which species of the Arboreal Orders find their Paradise, and hold undisturbed possession. Myriads of climbing birds—parrots, macaws, and cockatoos—fill the whole atmosphere with joyful screams, deafening the very monkeys with their din; gorgeous toucans, with enormous bills and feathers dipped in flame, and woodpeckers scarcely less gaily clad, make the woods echo, as with axe-like beaks they chop their way in search of insect food.

The peculiar structure of the feet in the arboreal races is evidently adapted to a life amongst the branches of trees: the outer toe can be directed backwards like a thumb, enabling them to grasp the boughs as with a hand.

If, leaving the trackless gloom of the forest, we approach the sylvan scenery of the surrounding country, the "bosky woods" and isolated trees, or the sparse undergrowth of bushy shrubs, we find innumerable forms that have their feet contrived for perching only. These Insessorial races, called also Passeres, from their general resemblance to sparrows, live upon insects, fruit, and grain; but those with strong beaks live more exclusively upon grain, and those with slender beaks upon insects. The proportional length of their wings is as variable as their habits. They have four toes, generally so disposed that there are three in front and one behind; sometimes all four in front. Their legs are slender, and they hop rather than walk.

The forests and the trees, the bushes and the brakes, the thickets and the hedgerows, being thus provided with appropriate denizens, we turn our attention to the level ground; and here we find species as obviously designed for a terrestrial existence as were the preceding groups for a residence among the branches. The terrestrial or Gallinaceous birds live principally upon the ground. Their body is large and heavy, and their wings short and rounded, so as to be but ill adapted to prolonged flight. They have three toes in front, which are united at their base by a short fold of the skin, and their hinder toe is affixed above the level of the rest. In many species the male is provided with formidable weapons in the shape of spurs. To this order belong the turkeys, pheasants, and barn-door fowls. Their legs are thick, strong, and muscular, their toes short and powerful. They always prefer running to flying, and, indeed, will rarely take to their wings, except when compelled to do so by the urgency of the occasion.

If any doubt could be entertained as to the terrestrial character of the gallinaceous birds, there can be none whatever as to those distinguished by the name of Cursores or runners. The principal characteristic of the cursorial race consists in the undeveloped condition of their wings, which are quite disproportioned to the size of their body. In some cases these rudimentary wings are but imperfectly furnished with feathers, and seem only to be used after the manner of sails, to catch the wind, and thus assist in running. The living species form two families, of one of which the Ostrich, and of the other the Apteryx, is the type.

Leaving the firm dry land, we next turn our attention to the marshes—the dubious confines between land and water—and here we find the order of Waders, or, as they have been named on account of their long stilt-like legs, Grallatores or stilt-walkers. These birds, as their name imports, are characterised by the height of their legs, which are naked, and thus adapted for wading to a certain depth into the water, where many species catch their prey. A remarkable example is met with in this order of the facility with which difficulties, apparently insurmountable, in the adaptation of certain species to peculiar circumstances, have been encountered and overcome. In India, the tanks and ponds of considerable depth are more or less covered with the broad leaves of water-lilies and other floating vegetation. In such places, which are far too deep to be occupied by wading birds, and yet too extensive to be left without inhabitants, we find a family provided with toes so enormously lengthened, and moreover eked out by claws of such extraordinary length, that the spread of their feet extends over a very large surface, thus enabling them to walk over the floating weeds.

Another order of birds comprehends those whose feet are specially constructed for swimming, constituting a NATATORIAL TYPE; for this purpose they are placed far back upon the body, the legs are short and compressed, and the toes are united by a web. Their plumage is thick and shining, impregnated with oil, and closely packed with soft down, so as to preserve them from all contact with the water. They are the only birds the length of whose neck much surpasses that of their legs, thus enabling them, while swimming at the surface, to obtain their food at the bottom. Such are the Ducks and Swans, which are, moreover, further characterised by having their bill covered with a soft skin, and furnished occasionally at the sides with ridges and tooth-like points. The Divers, trusting to their superior powers of battling with the watery element, are met with further from the shore; while, at distances still more remote from land, daring the utmost fury of the tempestuous ocean, walking upon the waters, or riding upon the seas—

Lastly, in this our rapid survey of the distribution of the feathered tribes, we have to speak of those whose element is the air. And here, perhaps, the reader may feel inclined to remark that, with the exception of the cursorial birds, such as the Ostriches and the Apteryx, all the species we have had occasion to mention are more or less capable of flight—that this is the special attribute of the whole class. Nevertheless, upon a little consideration, he will find that amongst the many races that fly well, there are some so pre-eminent in this respect that all others quail before them. It is one thing to be able to fly, and another to be furnished with wings so powerful that they never seem to tire. It is one thing to be the champion of the coppice, but another to be the tyrant of the sky!

The greatest powers of flight are of course conferred upon the rapacious birds, whose business is to overtake and destroy their swift-flying prey. To enable them to do this, their wings are necessarily of the most perfect structure; and they may also be recognised by their feet, which are strong, and armed with formidable talons. Of the swiftness of the falcon we have spoken elsewhere; and any one who has witnessed the flight of the eagle is not likely to have forgotten so grand a spectacle; his movements are majestic, and as he sails above the clouds on outstretched wings he seems to feel himself the monarch of the scene around. And yet even the falcon and the eagle cannot, as regards their powers of flight, be looked upon as the most highly gifted of flying birds. The spread of wing of the frigate-birds measures ten feet from tip to tip, and their flight is so powerful that they are everywhere to be seen in tropical climates at immense distances from land; while the albatross has been known to fly around a ship for weeks together, exhibiting such indomitable strength of wing that it has been supposed to be capable of circling round the world.

It is by no means our intention to trouble the reader with unnecessary details concerning the anatomy of the creatures upon the history of which he is about to enter; nevertheless, it is indispensably requisite that we should give at least an outline of their internal organisation.

No one can have examined attentively the bony framework whereby the body of a bird is sustained, without being forcibly impressed with the lightness as well as the compactness of its construction. The most wonderful economy is exhibited in the arrangement of the weighty material of which it consists. The bones present in their interior extensive cavities, whereby they are considerably lightened, and their walls, although exceedingly dense and strong, are much thinner than in any other animals. The extremities of the cylindrical bones are occupied by a light open network of slender filaments shooting across in every direction from wall to wall, and as these attenuated buttresses are likewise hollow, it is easy to perceive how incomparably lightness and strength are here conjoined.

The extent to which the skeleton is thus filled with air varies in different birds in relation with their powers of flight. In the Swifts and the Humming-birds every bone of the skeleton, even to the toes and the claws, is permeated by the atmospheric fluid. In the opposite extreme, the terrestrial Apteryx and the aquatic Penguin have not a single bone thus excavated.

Fig. 12.—SKELETON OF A BIRD.

a, the Skull; b, VertebrÆ of the Neck; c, Dorsal Region of the Spine; d, VertebrÆ that support the Tail; e, e, e, the Sternum or Breast-bone; f, f, f, f, the Ribs; h, the Scapula, or Shoulder-blade; i, i, the conjoined Clavicles or Collar-bones, forming the Furculum, or "Merry-thought;" k, the Coracoid Bones; l, the Humerus, or Arm-bone; m, n, Bones of the Fore-arm; o, b', Bones of the Wrist or Carpus; p, p, the Metacarpal Bones and Rudimentary Thumb; q, q, Pieces representing the Middle Finger; r, s, s, the Pelvis, formed by the consolidation of the hinder VertebrÆ of the Back into one piece; t, the Thigh-bone; u, the Leg; x, x, the Tarso-Metatarsal Bones, usually called the Tarsus; y, the Hallux, or Hinder Toe; z, z, the Front Toes.