THE word Nature has in all languages two very different acceptations. It denotes either that Being, to the operation of which we usually ascribe the chain of effects that constitute the phoenomena of the universe ; or it signifies the aggregate of the qualities implanted in man, or in the various quadrupeds, and birds, &c. It is active nature that, stamping their peculiar characters, thus forms passive nature ; whence are derived the instincts of animals, their habits and their faculties. We have in a former work treated of the nature of Man and the Quadrupeds ; that of Birds now demands our attention : and though the subject is, in many respects, more obscure, we shall endeavour to select the discriminating features, and to place them in the proper point of view Perception, or rather the faculty of feeling ; instinct, which results from it ; and talent, which consists in the habitual exercise of the natural powers ; are widely distinguished in different beings. These intimate qualities depend upon organization in general, and especially upon that of the senses : they are not only proportioned to the degree of the perfection of these ; they have also a relation to the order of superiority that is established. In man, for instance, the sense of touch is more exquisite than in all other animals ; in these, on the contrary, smell is more perfect than in man : for touch is the foundation of knowledge, and smell is only the source of perception. But, as few persons distinguish nicely the shades that discriminate between ideas and sensations, knowledge and perception, reason and instinct, we shall set aside what are termed ratiocination, discernment and judgement ; and we shall only consider the different combinations of simple perception, and endeavour to investigate the causes of that diversity of instinct, which, though infinitely varied in the immense number of species, seems more constant, more uniform, and more regular, and less subject to caprice and error, than reason in the single species which boasts the possession of it.
In comparing the senses, which are the primary powers that readily excite and impel the instinct in all animals, we find that of flight to be more extended, more acute, more accurate, and more distinct in the birds in general, than in the quadrupeds : I say in general, for there are some birds, such as the owls, that have less clear vision than the quadrupeds ; but this, in fact, results from the excessive sensibility of the eye, which, though it cannot support the glare of noon-day, distinguishes nicely objects in the glimmering of the evening. In all birds the organ of sight is furnished with two membranes, an external and internal, additional to those which occur in man : the former*, or external membrane, is placed in the large angle of the eye, and is a second and more transparent eyelid, whose motions too are directed at pleasure, and whose use is to clear and polish the cornea : it serves also to temper the excess of light, and consequently to adjust the quantity admitted, to the extreme delicacy of the organ : the † other is situated at the bottom of the eye, and appears to be an expansion of the optic nerve, which, receiving more immediately the impressions of the rays, must be much more sensible than in other animals ; and hence the sight is in birds vastly more perfect, and embraces a wider range. A sparrow-hawk, while he hovers in the air, espies a lark sitting on a clod, though at twenty times the distance at which a man or dog could perceive it, A kite which soars to so amazing a height as totally to vanish from our sight, yet distinguishes the small lizards, field-mice, birds, &c. and from this lofty station he selects what he destines to be victims of his rapine. But this prodigious extent of vision is accompanied likewise with an equal accuracy and clearness ; for the eye can dilate or contract, can be shaded or uncovered, depressed or made protuberant, and thus it will readily assume the precise form suited to the quantity of light and the distance of the object.
* This internal eye-lid (membrana nictitans) occurs in several quadrupeds ;
but in most of them it is not moveable as in birds.
†"In the eyes of a turkey cock, the optic nerve, which was situated very near
the side, after perforating the sclerotic and choroid coats, spread into
a round space, from the circumference of which a number of black filaments
were sent off to form by their union a membrane which is found in all birds."
--- "In the eyes of the ostrich, the optic nerve, after perforating the sclerotic
and choroid coats, was dilated into a sort of funnel of a similar substance :
this funnel is not commonly round in birds, where we have almost always found
the extremity of the optic nerve flattened and compressed within the eye :
from this funnel a folded membrane took its origin, forming a sort of purse
that drew to a point. This purse, which was six lines broad at the base,
where it grew out of the optic [… page 4 …] nerve, was black, and seemed imbued,
and quite penetrated by that colour, which on the choroid is only spread, and
may be rubbed off with the fingers." Memoires pour servir à l’Hist. des Anim.
Sight has a reference also to motion and space ; and, if birds trace the most rapid course, we might expect them to possess in a superior degree that sense which is proper to guide and direct their flight. If Nature, while she endowed them with great agility and vast muscular strength, had formed them short-sighted, their latent powers would have availed them nothing ; and the danger of dashing against every intervening obstacle would have repressed or extinguished their ardour. Indeed, we may consider the celerity with which an animal moves, as the just indication of the perfection of its vision. A bird, for instance, that shoots swiftly through the air, must undoubtedly see better than one which slowly describes a waving tract. Among the quadrupeds too, sloths have their eyes enveloped, and their sight is limited.
The idea of motion, and all the other ideas which accompany or flow from it, such as those of relative velocities, of the extent of country, of the proportional height of eminences, and of the various inequalities that prevail on the surface, are, therefore, more precise in birds, and occupy a larger share of their conceptions than in quadrupeds. Nature would seem to have pointed out this superiority of vision by the more conspicuous and more elaborate structure of its organ ; for in birds the eye is larger in proportion to the bulk of the head than in quadrupeds * ; it is also more delicate and more finely fashioned, and the impressions which it receives must excite more vivid ideas. Another cause of the difference between the instincts of birds and of quadrupeds, is the nature of the element in which they live. The birds know better than man, perhaps, all the degrees of resistance of the air, its temperature at different heights, its relative density, &c. They foresee more than us, they indicate better than our barometers or thermometers, the changes which happen in that voluble fluid. Often have they struggled against the violence of the wind, and oftener have they borrowed its aid. The eagle, soaring above the clouds†, can quickly escape from the scene of the storm to the region of calm, and there enjoy a serene sky and a bright sun, while the other animals below are involved in darkness, and exposed to all the fury of the tempest. In twenty-four hours it can change its climate, and failing over the different countries, it will form a picture which exceeds the powers of our imagination. Our bird’s-eye views, of which the accurate execution is so tedious and so difficult, give very imperfect notions of the relative inequality of the surfaces which they represent. But birds can chuse the proper stations, can successively traverse the field in all directions, and with one glance comprehend the whole. The quadruped knows only the spot where it feeds; its valley, its mountain, or its plain : it has no conception of the expanse of surface, no idea of immense distances, and no desire to put forward its excursions. Hence remote journies and migrations are as rare among the quadrupeds as they are frequent among the birds. It is this desire, founded on their acquaintance with foreign countries, on the consciousness of their expeditious course, and on their foresight of the changes that will happen in the atmosphere and of the revolution of seasons, that prompt them to retire together, and by common consent. When their food begins to grow scarce, when, as the cold or the heat incommodes them, they resolve on their retreat, the parents collect their young, and the different families assemble and communicate their views to the unexperienced ; and the whole body, strengthened by their numbers, and actuated by the same common motives, wing their journey to some distant land.
* "The ball of the eye in a female eagle was, at its greatest width,
an inch and half in diameter ; that of the male was three lines less."
Mem. Pour servir à Hist. des Animaux.
The ball of the ibis' eye was six lines in diameter.
The eye of the stork four times larger. Idem.
The ball of the cassowary's eye was four times larger than its cornea,
being an inch and half in diameter, though the cornea was only three lines. Idem.
† It can be proved that the eagle, and other birds of lofty flight,
can rife perpendicularly above the clouds ; for they frequently mount
entirely out of our sight. But in day-light an object ceases to be visible
when it exceeds 3,436 times its diameter ; if, therefore, the extent of the
bird be five feet, it will be seen at the height of 17,180 feet, or above three miles.
This propensity to migration, which recurs every spring and autumn, is a sort of violent longing, which, even in captive birds, bursts out in symptoms of restless and uneasy sensations.
We shall, at the article of the Quail, give a detail of observations on this subject ; from which It will appear, that this propensity is one of their most powerful instincts ; and that, though they usually remain tranquil in their prison, they make every exertion at those periods to regain their liberty, and join their companions. — But the circumstances which attend migration vary in different birds; and, before we enter into the full discussion which that subject merits, we shall pursue our investigation of the causes that form and modify their instincts.
Man is eminently superior to all the animals in the sense of touch, perhaps too in that of taste ; but he is inferior to most of them in the other three senses. When we compare the animals with each other, we soon perceive that smell in general is more acute among the quadrupeds than among the birds : for though we speak of the scent of the crow, of the vulture, &c. it undoubtedly obtains in a much lower degree ; and we might be convinced of this by merely examining the structure of the organ. In most of the winged tribes, the external nostrils are wanting, and the effluvia, which excite the sensation, have access only to the duct leading from the palate * : and even in those where the organ is disclosed, the nerves, which take their origin from it, are far from being so numerous, so large, or so expanded, as in the quadruped.
* Hist. de I'Acad. des Sciences, tome i. p. 430.
We may therefore regard touch in man, smell in the quadruped, sight in the bird, as the three mod perfect senses, and which influence the general character.
Next to sight, the most perfect of the senses in birds is hearing, which is even superior to that of the quadrupeds. We perceive with what facility they retain and repeat tones, successions of notes, and even discourse ; we delight to listen to their unwearied songs, to the incessant warbling of their happy loves. Their ear and throat are more ductile and more powerful than in other animals. Most of the quadrupeds are habitually silent ; and their voice, which is seldom heard, is almost always harsh and disagreeable. In birds it is sweet, pleasant, and melodious. There are some species, indeed, in which the notes seem unsupportable, especially if compared with those of others ; but these are few in number, and comprehend the large kinds, which Nature, bestowing on them hoarse loud cries, suited to their bulk, would incline to treat like quadrupeds. A peacock, which is not the hundredth part of the size of an ox, may be heard farther ; the nightingale could fill a wider space with its music than the human voice : this prodigious extent, and the great powers of their organs of sound, depend entirely on the structure ; but that their song should be continued and supported, results solely from their internal emotions. These two circumstances ought to be considered separately.
The pectoral muscles are more fleshy and much stronger in birds than in man or the quadrupeds, and their action is immensely greater. Their wings are broad and light, composed of thin hollow bones, and connected by powerful tendons. The ease with which birds fly, the celerity of their course, and even their power of directing it upwards or downwards, depend on the proportion of the impelling surface to the mass of the body. When they are ponderous, and the wings and tail at the same time short, like the bustard, the cassowary, or the ostrich, they can hardly rise from the ground.
The windpipe is wider and stronger in birds than in quadrupeds, and usually terminates below in a large cavity that augments the sound. The lungs too have greater extent, and send off many appendices which form air-bags, that at once assist the motion, by rendering the body specifically lighter, and give additional force to the voice. A little production of the cartilage of the trachea in the howling baboon †, which is a quadruped of a middle size only, and of the ordinary structure, has enabled it to scream almost without intermission, and so loud, as to be heard at more than a league’s distance : but in birds the formation of the thorax, of the lungs, and of all the organs connected with these, seems expressly calculated to give force and duration to their utterance; and the effect must be proportionally greater *.
* Simia -Beelzebut. Linn.
† In most water-fowls, which have a very strong voice, the trachea
reverberates the sound ; for the glottis is placed below it, and not
above it, as in man. Coll, Acad. Part. Sr. tome i. 496.—
The same is the case in the cock. Hist. de l’Acad. tome ii, 7.
In birds, especially ducks and other water-fowls, the organs of voice
consist of an internal larynx placed where the trachea arteria parts ;
of two membranous pipes which communicate below with the two first branches
of the trachea; of many semilunar membranes, disposed one above another
in the principal branches of the fleshy lungs, and which, occupying only
one half of their cavity, allow a free exit to the air ; of other membranes
placed in various positions, both in the middle and in the lower part of the
trachea ; and lastly, of a membrane, of more or less solidity, situated
almost transversely between the two branches of the lunula, which terminates
a cavity that constantly occurs in the upper and internal part of the breast.
Mem. de l’Acad. des Sciences, anné 1753.
There is another circumstance which evinces that birds have a prodigious power of voice : the cries of many species are uttered in the higher regions of the atmosphere, where the rarity of the medium must consequently weaken the effect. That the rarefaction of the air diminishes sounds is well ascertained from pneumatical experiments ; and I can add, from my own observation, that, even in the open air, a sensible difference in this respect: may be perceived. I have often spent whole days in the forests, where I was obliged to listen closely to the distant cries of the dogs, or shouts of the hunters ; I uniformly found that the same noises were much less audible during the heat of the day, between ten and four o’clock, than in the evening, and particularly in the night, whose stillness would make hardly any alteration, since in these sequestered scenes there is nothing to disturb the harmony but the slight buzz of insects and the chirping of some birds. I have observed a similar difference between the frosty days in winter and the heats of summer. This can be imputed only to the variation in the density of the air. Indeed, the difference seems to be so great, that I have often been unable to distinguish in mid-day, at the distance of six hundred paces, the same voice which I could, at six o’clock in the morning or evening, hear at that of twelve or sixteen hundred paces. — A bird may rise at least : to the height of seventeen thousand feet, for it is there just visible. A flock of several hundred storks, geese, or ducks, must mount still higher, since, notwithstanding the space which they occupy, they soar almost out of sight. Is the cry of birds therefore maybe heard from an altitude of above a league, we may reckon it at least four times as powerful as that of men or quadrupeds, which is not audible at more than half a league’s distance on the surface. But this estimation is even too low : for, beside the dissipation of force to be attributed to the cause already assigned, the sound is propagated in the higher regions as from a centre in all directions, and only a part of it reaches the ground ; but, when made at the surface, the aerial waves are reflected as they roll along, and the lateral and vertical effect is augmented. It is hence that a person on the top of a tower hears one better at the bottom, than the person below hears from above.
Sweetness of voice and melody of song are qualities which in birds are partly natural, partly acquired. Their great facility in catching and repeating sounds enables them not only to borrow from each other, but often to copy the inflexions and tones of the human voice, and of our musical instruments. Is it not singular, that in all populous and civilized countries, most of the birds chant delightful airs, while, in the extensive deserts of Africa and America, inhabited by roving savages, the winged tribes utter only harsh and discordant cries, and but a few species have any claim to melody ? Must this difference be imputed to the difference of climate alone ? The extremes of cold and heat operate indeed great changes on the nature of animals, and often form externally permanent characters and vivid colours. The quadrupeds of which the garb is variegated, spotted, or striped, such as the panthers, the leopards, the zebras, and the civets, are all natives of the hottest climates. All the birds of the tropical regions sparkle with the most glowing tints, while those of the temperate countries are stained with lighter and softer shades. of the three hundred species that may be reckoned belonging to our climates, the peacock, the common cock, the golden oriole, the king-fisher, and the goldfinch, only can be celebrated for the variety of their colours ; but Nature would seem to have exhausted all the rich hues of the universe on the plumage of the birds of America, of Africa, and of India. These quadrupeds, clothed in the most splendid robes, these birds attired in the richest plumage, utter at the same time hoarse, grating, or even terrible cries. Climate has no doubt a principal share in this phænomenon ; but does not the influence of man contribute also to the effect? In all the domesticated animals, the colours never heighten, but grow softer and fainter : many examples occur among the quadrupeds ; and cocks and pigeons are still more variegated than dogs or horses. The real alteration which the human powers have produced in nature, exceeds our fondest imagination : the whole face of the globe is changed ; the milder animals are tamed and subdued, and the more ferocious are repressed and extirpated. They imitate our manners ; they adopt our sentiments ; and, under our tuition, their faculties expand. In the state of nature, the dog has the same qualities and dispositions, though in an inferior degree, with the tiger, the Leopard, or the lion ; for the character of the carnivorous tribe results solely from the acuteness of their smell and taste : but education has mollified his original ferocity, improved his sagacity, and rendered him the companion and associate of man.
Our influence is smaller on the birds than on the quadrupeds, because their nature is more different from our own, and because they are less submissive and less susceptible of attachment. Those we call domestic are only prisoners, which, but for propagating, are useless during their lives ; they are victims, multiplied without trouble, and sacrificed without regret. As their instincts are totally unrelated to our own, we find it impossible to instil our sentiments ; and their education is merely mechanical. A bird, whose ear is delicate, and whose voice is flexible, listens to discourse, and soon learns to repeat the words, but without feeling their force. Some have indeed been taught to hunt and fetch game ; some have been trained to fondle their instructor : but these sentiments are infinitely below what we communicate so readily to the quadrupeds. What comparison between the attachment of a dog, and the familiarity of a canary bird ; between the understanding of an elephant, and the sagacity of an ostrich ?
The natural tones of birds, setting aside those derived from education, express the various modifications of passion ; they change even according to the different times or circumstances.
The females are much more silent than the males ; they have cries of pain or fear, murmurs of inquietude or solicitude, especially for their young ; but song is generally withheld from them. In the male it springs from sweet emotion, from tender desire ; the canary in his cage, the greenfinch in the fields, the oriole in the woods, chant their loves with a sonorous voice, and their mates reply in feeble notes of consent. The nightingale, when he first arrives in the spring, is silent ; he begins in saultering unfrequent airs : it is not until the dam sits on her eggs, that he pours out the warm melody of his heart : then he relieves and soothes her tedious incubation ; then he redoubles his caresses, and warbles more pathetically his amorous tale. And what proves that love is among birds the real source of their music is, that, after the breeding season is over, it either ceases entirely, or loses its sweetness.
This melody, which is each year renewed, and which lasts only two or three months during the season of love, and changes into harsh low notes on the subsidence of that passion, indicates a physical relation between the organs of generation and those of voice, which is most conspicuous in birds. It is well known that the articulation is never confirmed in the human species before the age of puberty ; and that the bellowing of quadrupeds becomes tremendous when they are actuated by their fiery lusts. The repletion of the spermatic vessels irritates the parts of generation, and by sympathy affects the throat. Hence the growth of the beard, the forming of the voice, and the extension of the genital organ in the male ; the swell of the breasts, and the expansion of the glandulous bodies in the female. In birds the changes are more considerable ; not only are these parts stimulated or altered ; after being in appearance entirely destroyed, they are even renovated by the operation of the same causes. The testicles, which in man and most of the quadrupeds remain nearly the same at all times, contract and waste almost entirely away in birds after the breeding season is over, and on its return they expand to a size that even appears disproportioned. It would be curious to discover if there is not some new production in the organs of the voice, corresponding to this swell in the parts of generation.
Man seems even to have given a direction to love, that appetite which Nature has the most deeply implanted in the animal frame. The domestic quadrupeds and birds are almost constantly in season, while those which roam in perfect freedom are only at certain stated times stimulated by the ardour of passion. The cock, the pigeon, and the duck, have, equally with the horse, the ram, and the dog, undergone this important change of constitution.
But the birds excel the other animals in the powers of generation, and in their aptitude for motion. Many species scarcely rest a single moment, and the rapacious tribes pursue their prey without halting or turning aside, while the quadrupeds need to be frequently recruited. — To give some idea of the rapidity and continuance of the flight of birds, let us compare it with the celerity of the fleetest land-animals. The stag, the rein-deer, and the elk, can travel forty leagues a-day ; the rein-deer can draw its sledge at the rate of thirty leagues for several days. The camel can perform a journey of three hundred leagues in eight days. The choicest racehorse can run a league in six or seven minutes ; but he soon slackens his career, and could not long support such an exertion. I have elsewhere mentioned the instance of an Englishman who rode sixty-two leagues in eleven hours and thirty-two minutes, changing horses twenty-one times : so that the best horse could not travel more than four leagues in an hour, or thirty leagues in a day. But the motion of birds is vastly swifter : an eagle, whose diameter exceeds four feet, rises out of sight in less than three minutes, and therefore must fly more than 3,500 yards in one minute, or twenty leagues in an hour. At this rate, a bird would easily perform a journey of two hundred leagues in a day, since ten hours would be sufficient, which would allow frequent halts, and the whole night for repose. Our swallows, and other migratory birds, might therefore reach the equator in seven or eight days.
Adanson saw on the coast of Senegal swallows that had arrived on the ninth of October ; that is, eight or nine days after their departure from Europe*. Pietro della Valle says, that in Persia † the messenger-pigeon travels as far in a single day as a man can go a-foot in six days. It is a well-known story, that a falcon of Henry II. which flew after a little bustard at Fontainbleau, was caught next morning at Malta, and recognized by the ring which it wore ‡. A Canary falcon, sent to the duke of Lerma, returned in sixteen hours from Andalusia to the island of Teneriffe, a distance of two hundred and sixty leagues. Sir Hans Sloane || assures us, that at Barbadoes the gulls make excursions in flocks to the distance of more than two hundred miles, and return the same day. Taking all these facts together, I think we may conclude that a bird of vigorous wing could every day pass through four or five times more space thanthe fleetest quadruped.
Every thing conspires to the rapidity of a bird’s motion : first, the feathers are very light, have a broad surface, and their shafts are hollow : secondly, the wings are convex above and concave below ; they are firm and wide spread, and the muscles which act upon them are powerful : thirdly, the body is proportionally light, for the flat bones are thinner than in the quadrpeds, and hollow bones have much larger cavities. ” The skeleton of the pelican,” say the anatomists of the Academy, ” is extremely light, not weighing more than twenty-three ounces, though it is of considerable bulk.” This quality diminishes the specific gravity of birds.
* Voyage au Senegal.
† Voyage de Pietro della Valle.
‡ Observations of Sir Edmund Scoty, in Purchass's Collection.
|| A Voyage to the West Islands, with their Natural History, by Sir Hans Sloane.
Another consequence which seems to result from the texture of the bones, is the longevity of birds. In man and the quadrupeds, the period of life seems to be in general regulated by the time required to attain the full growth : but in birds it follows different proportions ; their progress is rapid to maturity ; some run as soon as they quit the shell, and fly shortly afterwards : a cock can copulate when only four months old, and yet does not acquire his full size in less than a year. Land animals generally live six or seven times as long as they take to reach the age of puberty ; but in birds the proportion is ten times greater, for I have seen linnets fourteen or sixteen years old, cocks twenty, and parrots above thirty, and they would probably go beyond these limits *. This difference I should attribute to the soft porous quality of the bones; for the general ossification and rigidity of the system to which animals perpetually tend, determine the boundary of life ; that will therefore be prolonged, is the parts want solidity and consistence. It is thus that women arrive oftener at old age tiian men ; that birds live longer than quadrupeds, and that fishes live longer than birds.
* A person of veracity assured me, that a parrot layed at about forty
years of age, without commerce with any male, at least of its own kind.
—It is said, that a swan has lived three hundred years ; a goose eighty ;
and a pelican as many. The eagle and crow are famous for longevity.
Encyclopedie, article Oiseau. — Aldrovandus relates, that a pigeon
lived twenty-two years, and ceased to breed only the last six years.
— Willoughby says, that linnets live fourteen years, and goldfinches
But a more particular inquiry will evince that uniformity of plan which prevails through nature. The birds, as well as the quadrupeds, are carnivorous, or granivorous. In the former class, the stomach and intestines are proportionally small ; but those of the latter have a craw additional, corresponding to the false belly in ruminating animals, and the capacity of the ventricle compensates for the unsubstantial quality of their destined food. The granivorous birds have also two cœca, and a very strong muscular stomach, which serves to triturate the hard substances which they swallow.
The dispositions and habits of animals depend greatly on their original appetites. We may therefore compare the eagle, noble and generous, to the lion ; the vulture, cruel and insatiable, to the tiger ; the kite, the buzzard, the crow, which only prowl among carrion and garbage, to the hyænas, the wolves, and jackals. The falcons, the sparrow-hawks, the gos-hawks, and the other birds trained for sport, are analogous to the dogs, the foxes, the ounces, and the lynxes ; the owls, which prey in the night, represent the cats ; the herons, and the cormorants, which live upon fish, correspond to the beavers and otters ; and, in their mode of subsistence, the woodpeckers resemble the ant-eaters. The common cock, the peacock, the turkey, and all the birds furnished with a craw, bear a relation to the ox, the sheep, the goat, and other ruminating animals. With regard to the article of food, birds have a more ample latitude than quadrupeds ; flesh, fish, the amphibious tribes, reptiles, insects, fruits, grain, seeds, roots, herbs ; in a word, whatever lives or vegetates. Nor are they very nice in their choice, but often catch indifferently at what they can most easily obtain. The sense of taste is much less acute in birds than in quadrupeds ; for, if we except such as are carnivorous, their tongue and palate are in general hard, and almost cartilaginous. Smell can alone direct them, and this they possess in an inferior degree. The greater number swallow without tasting, and mastication, which constitutes the chief pleasure in eating, is entirely wanting to them. Hence, on all these accounts, they are so little attentive to the selection of their food, that they often poison themselves *.
* Parsley, coffee, bitter almonds, &c. prove poisonous to hens,
parrots, and many other birds, which eat these substances
with avidity when presented with other food.
The attempt is impossible therefore to distinguish the winged tribes according to the nature of their aliments. The more constant and determined appetites of quadrupeds might countenance such a division * ; but in birds, where the taste is so irregular, it would be entirely nugatory. We see hens, turkies, and other fowls which are called granivorous, eat worms, insects, and bits of flesh with greater avidity than grain. The nightingale, which lives on insects, may be fed with minced meat ; the owls, which are naturally carnivorous, often when other prey fails, catch night-flies in the dark ; nor is their hooked bill, as those who deal in final causes maintain, any certain proof that they have a decided propensity for flesh, since parrots and many other birds which seem to prefer grain have also a hooked bill. The more voracious kinds devour fish, toads, and reptiles, when they cannot obtain flesh. Almost all the birds which appear to feed upon grain, were reared by their parents with insects. The arrangement derived from the nature of the food is thus totally destitute of foundation. No one character is sufficient : it requires the combination of many.
* Frisch, whose work is in many respects valuable, divides all
birds into twelve classes. The first contains the small birds,
with a thick short bill, which split seeds into two equal portions ;
the second includes the small birds with a slender bill, that eat flies
and worms ; the third comprehends the black-birds and thrushes ;
the fourth, the woodpeckers, cuckoos, hoopoes, and parrots ;
the fifth, the jays and magpies ; the sixth, the rooks and crows ;
the seventh, the diurnal birds of prey ; the eighth, the nocturnal birds of prey ;
the ninth, the wild and tame poultry ; the tenth, the wild and tame pigeons;
the eleventh, the geese, ducks, and other swimming animals ;
the twelfth, the birds which are fond of water and wet places.
– We easily see that the instinct of opening seeds in two equal portions ought
not to be adopted as a character, since in this same class there are birds,
such as the titmice, that do not split them, but pierce and tear them ; and that,
besides, all the birds of this first class, which are supposed to subsist solely
on seeds, seed likewise on insects and worms : it was better, therefore,
as Linnæus has done, to join them into one class.
Since birds cannot chew, and the mandibles which represent the jaws are unprovided with teeth, the grains are swallowed whole, or only half-bruised *. But the powerful action of the stomach serves them instead of mastication ; and the small pebbles, which assist in trituration, may be conceived to perform the office of teeth †.
* In parrots, and many other birds, the upper mandible is moveable as well as
the under ; whereas in quadrupeds the lower jaw only is moveable.
† In no animals is the mode of digestion so favourable as in birds to the system
of trituration. Their gizzard has the proper force and direction of fibres ;
and the voracious kinds, which greedily snatch the seeds on which they feed
without stopping to separate the hard crust which envelopes them, swallow
at the same time little stones, by means of which the violent contraction
of the coats of the stomach bruises and detaches the shell. This is a real
trituration, which in other animals is performed by the teeth. But,
after the seeds are decorticated, the action of a solvent may take place ;
and there is a sort of bag from which a large quantity of a whitish liquor
slows into the stomach, for in a recently dead bird it may be pressed out.
Helvetius subjoins, that sometimes in the œsoshagus of the cormorant, fish are
found half digested. Hist, de l’Academie des Sciences, année 1719.
Seventy doubles were found in the stomach of an ostrich, most of them
worn three-fourths, and furrowed by their rubbing against each other
and against the pebbles, but not at all affected by solution, for some
which happened to be crooked were quite polished on the convex side, while
the concave side was not altered. Mémoires pour servir à l'Histoire des Animaux.
A Spanish gold pistole swallowed by a duck had lost sixteen grains
of its weight when voided. Collect. Acad. Partie Etrangère.
As Nature has invested the quadrupeds which haunt marshes, or inhabit cold countries, with a double fur, and with thick close hair ; so has she clothed the aquatic birds, and those which live in the northern tracts, with abundance of plumage, and a fine down ; insomuch that, from this circumstance alone, we may judge of their proper element, or of their natal region. In all climates, the birds which dwell in the water are nearly equally feathered, and have under the tail large glands, containing an oily substance for anointing their plumes, which, together with their thickness, prevents the moisture from insinuating. These glands are much smaller in the land-birds, or totally wanting.
Birds that are almost naked, such as the ostrich, the cassowary, and the dodo, occur only in the warm climates. All those which inhabit cold countries are well clothed with plumage. And for the same reason, those which soar into the higher regions of the atmosphere require a thick covering, that they may encounter the chilness which there prevails. If we pluck the feathers from the breast of an eagle, he will no longer rise out of our sight.
The greater number of birds cast their feathers every year, and appear to suffer much more from it than the quadrupeds do from a similar change. The best fed hen ceases at that time to lay. The organic molecules seem then to be entirely spent on the growth of the new feathers. The season of moulting is generally the end of summer or autumn *, and their feathers are not completely restored till the beginning of spring, when the mildness of the air, and the superabundance of nutrition, urge them to love. Then all the plants shoot up, the insects awaken from their long slumber, and the earth swarms with animation. This ample provision softens their ardent passions, and offers abundant subsistence to the fruits of their embrace.
We might deem it as essential to the bird to fly, as it is to the fish to swim, or to the quadruped to walk ; yet in all these tribes there are exceptions to the general property. Among quadrupeds, the rufous, red and common bats, can only fly ; the seals, the sea-horses, and sea-cows, can only swim ; and the beavers and otters walk with more difficulty than swim: and, lastly, there are others, such as the sloth, which can hardly drag along their bodies. In the same manner, we find among birds the ostrich, the cassowary, the dodo, the touyou, &c. which are incapable of flying, and are obliged to walk ; others, such as the penguins, the sea-parrots, &c. which fly and swim, but never walk ; and others, in fine, which, like the bird of paradise, can neither walk nor swim, but are perpetually on the wing. It appears, however, that water is, on the whole, more suited to the nature of birds than to that of quadrupeds: for, if we except a few species, all the land animals shun that element, and never swim, unless they are urged by their fears or wants. Of the birds, on the contrary, a large tribe constantly dwell on the waters, and never go on shore, but for particular purposes, such as to deposite their eggs, &c. And what proves this position, there are only three or four quadrupeds which have their toes connected by webs ; whereas we may reckon above three hundred birds which are furnished with such membranes. The lightness of their feathers and of their bones, and even the shape of their body, contribute greatly to the facility with which they swim, and their feet serve as oars to impel them along. Accordingly, certain birds discover an early propensity to the water ; the ducklings sail on the surface of the pool long before they can use their wings.
* Domestic fowls generally moult in autumn ; partridges and pheasants,
before the end of summer ; and such as are kept in parks, cast their
feathers immediately after their first hatch. In the country, the
pheasants and partridges undergo that change about the close of July,
only the females which have had young are some days later. Wild ducks
moult rather before that time. I owe these remarks to M. Le Roy,
king's ranger at Versailles.
In quadrupeds, especially those which have their feet terminated by hard hoofs or nails, the palate seems to be the principal seat of touch as well as of taste. Birds, on the other hand, oftener feel bodies with their toes ; but the inside of these is covered with a callous skin, and their tongue and mouth are almost cartilaginous : so that, on both accounts, their sensations must be blunt.
Such then is the order of the senses which Nature has established in the different beings. In man, touch is the first, or the most perfect ; taste the second ; sight the third ; hearing the fourth ; and smell the sixth and last. In quadrupeds, smell is the first ; taste the second, or rather these two senses form only one ; sight the third ; hearing the fourth ; and touch the last. In birds, sight is the first ; hearing the second ; touch the third ; and taste and smell the last. The predominating sensations will also follow the same order : man will be most affected by touch ; the quadrupeds by smell ; and the birds by sight. These will likewise give a cast to the general character, since certain motives of action will acquire peculiar force, and gain the ascendency. Thus, man will be more thoughtful and profound, as the sense of touch would appear to be more calm and intimate ; the quadrupeds will have more vehement appetites; and the birds will have emotions as extensive and volatile as is the glance of sight.
But there is a sixth sense, which, though it intermits, seems, while it acts, to control all the others, and excites the most powerful emotions, and awakens the most ardent affections:— it is love. In quadrupeds, that appetite produces violent effects ; they burn with maddening desire ; they seek the female with savage ardor ; and they embrace with furious extasy. In birds it is a softer, more tender, and more endearing passion ; and, if we except those which are degraded by domestication, and a few other species, conjugal fidelity and parental affection are among them alike conspicuous. The pair unite their labours in preparing for the accommodation of their expected progeny ; and, during the time of incubation, their participation of the same cares and solicitudes continually augments their mutual attachment. After the eggs are hatched, a new source of pleasure opens to them, which, further strengthens the ties of affection ; and the tender charge of rearing the infant brood requires the joint attention of both parents. The warmth of love is thus succeeded by calm and steady attachment, which by degrees extends, without suffering any diminution, to the rising branches of the family.
The quadrupeds are impelled by unbridled lust, which never softens into generous friendship. The male abandons the female as soon as the cravings of his appetite are cloyed ; he retires to recruit his strength, or hastens to the embraces of another. The education of the young is devolved entirely on the female ; and as they grow slowly, and require her immediate protection, the maternal tenderness is ripened into a strong and durable attachment. In many species the mother leads two or three litters at one time. There are some quadrupeds, however, in which the male and female associate together ; such are the wolves and foxes : and the fallow-deer have been regarded as the patterns of conjugal fidelity. There are also some species of birds where the cock separates after satisfying his passion ; — but such instances are rare, and do not affect: the general law of nature.
That the pairing of birds is founded on the need of their mutual labours to the support of the young, appears clearly from the case of the domestic fowls. The male ranges at will among a seraglio of submissive concubines ; the season of love has hardly any bounds ; the hatches are frequent and tedious ; the eggs are often removed ; and the female never seeks to breed, until her prolific powers are deadened, and almost exhausted : besides, they bestow little care in making their nest, they are abundantly supplied with provisions, and by the assistance of man they are freed from all those toils and hardships and solicitudes which other birds feel and share in common. They contract: the vices of luxury and opulence, indolence and debauchery.
The easy comfortable condition of the domestic fowls, and their generous food, mightily invigorate the powers of generation. A cock can tread twelve or sixteen hens, and each embrace continues its influence for three weeks ; so that he may each day be the father of three hundred chickens. A good hen lays a hundred eggs between the spring and autumn ; but in the savage state she has only eighteen or twenty, and that only during a single season. The other birds indeed repeat oftener their incubations, but they lay fewer eggs. The pigeons, the turtles, &c. have only two ; the great birds of prey three or four ; and most other birds five or six.
Want, anxiety, and hard labour, check in all animals the multiplication of the species. This is particularly the case with birds ; they breed in proportion as they are well fed, and afforded ease and comfort. In the state of nature, they seem even to husband their prolific powers, and to limit the number of their progeny to the penury of their circumstances. A bird lays live eggs, perhaps, and devotes her whole attention during the rest of the season to the incubation and education of the young. But if the nest be destroyed, she soon builds another, and lays three or sour eggs more ; and if this be again plundered, she will construct a third, and lay still two or three eggs. During the first hatch, therefore, those internal emotions of love which occasion the growth and exclusion of the eggs, are repressed. She thus sacrifices duty to passion, amorous desire to parental attachment. But when her fond hopes are disappointed, she soon ceases to grieve ; the procreative faculties, which were suspended, not extinguished, again resume their influence, and enable her in some measure to repair her loss.
As love is a purer passion in birds than in quadrupeds, its mode of gratification is also simpler. Coition is performed among them only in one way*, while many other animals embrace in various postures † : only in some species, as in that of the common cock, the female squats ; and in others, such as the sparrow’s, she continues to stand erect. In all of them the act is transitory, and is still shorter in those which in their ordinary attitude wait the approach of the male, than in those which cower to receive him ‡. The external form and the internal structure of the organs of generation are very different from what obtains in quadrupeds. The size, the position, the number, the action and motion of these parts even vary much in the several species of birds*. In some there appears to be a real penetration ; in others, a vigorous compression, or slight touch. But we shall consider the details in the course of the work.
* Aristotle, lib. v. 8.
† The she-camel squats ; the she-elephant turns upon her back;
the hedgehogs couple face to face, and either in an erect or
reclined position ; and monkies in every manner.
‡ Aristotle, lib. v. 2.
To concentrate the different principles established in this discourse : that the sensorium of birds contains chiefly the images derived from the sense of sight ; and these, though superficial, are very extensive, and, for the most part, relate to motion, to distance, and to space : that comprehending a whole province within the limits of their horizon, they may be said to carry in their brain a geographical chart of the places which they view : that their facility in traversing wide territories is one of the causes which prompt their frequent excursions and migrations : that their ear being delicate, they are alarmed by sudden noises, but may be soothed by soft sounds, and allured by calls : that their organs of voice being exceedingly powerful and soft, they naturally vent their feelings in loud resounding strains : that, as they have more signs and inflexions, they can, better than the quadrupeds, express their meaning : that easily receiving, and long retaining the impressions of sounds, the organ delights in repeating them ; but that its imitations are entirely mechanical, and have no relation to their conceptions : that their sense of touch being obtuse, they have only imperfect ideas of bodies : that they receive their information of distant objects from sight, not from smell : that as their taste is indiscriminating, they are more prone to voracity than sensuality : that, from the nature of the element which they inhabit, they are independent of man, and retain their natural habits ; that, for this reason, most of them are attached to the society of their fellows, and eagerly convene : that, being obliged to unite their exertions in building a nest, and in providing for their offspring, the pair contract an affection for each other, which continues to grow, and then extends to the tender brood : that this friendship restrains the violent passions, and even tempers love, and begets chastity, and purity of manners, and gentleness of disposition : that, though their power of fruition is greater than in other animals, they consume its exercise within moderate bounds, and ever subject their pleasures to their duties : and, finally, that these sprightly beings, which Nature would seem to have produced in her gay moments, may be regarded as a serious and decent race, which exhibit excellent lessons and laudable examples of morality.
* Most birds have two yards, or a forked one projecting from the anus.
la some species the male organ is exceedingly large ; in others hardly
visible. The female orifice is not situated, as in the quadrupeds,
below the units, but above it ; and there is no matrix, &c.