Gay Plumes and Dull

JUNE, 1905

BY JOHN BURROUGHS

I

NOT long since, one of our younger naturalists sent me a photograph of a fawn in a field of daisies, and said that he took the picture to show what he considered the protective value of the spots. The white spots of the fawn did blend in with the daisies, and certainly rendered the fawn less conspicuous than it would have been without them, but I am slow to believe that the fawn has spots that it may the better hide in a daisy field, or, in fact, anywhere else, or that the spots have ever been sufficiently protective to have materially aided in the perpetuity of the deer species. What use they have, if any, I do not know, any more than I know what use the spots on the leopard or the giraffe have, or the stripes on the zebra. I can only conjecture concerning their use. The panther does not have spots, and yet it seems to get along just as well without them. The young of the moose and the caribou are not spotted, and yet their habitat is much the same as that of the deer.

Why some forest animals are uniformly dark colored, while others are more or less brilliantly striped or spotted, is a question not easily answered. It is claimed that spotted and striped species are more diurnal in their habits, and frequent bushes and open glades, while the dusky species are more nocturnal, and frequent dense thickets. In a general way this is probably true. A dappled coat is certainly more in keeping with the day than with the night, and with bushes and jungles than with plains or dense forests. But whether its protective value, or the protective value of the dusky coat, is the reason for its being, is another question.

This theory of the protective coloration of animals has been one of the generally accepted ideas in all works upon natural history since Darwin’s time. It regards the color of an animal as much the result of natural selection as any part of its structure, — natural selection picking out and preserving those tints that were the most useful to the animal in concealing it from its enemies or from its prey. If in this world no animal had ever preyed upon another, it is thought that their colors might have been very different, probably much more bizarre and inharmonious than they are at present.

Now I am not going to run amuck upon this generally accepted theory of modern naturalists, but I do feel disposed to shake it up a little, and see, if I can, what measure of truth there is in it. That there is a measure of truth in it I am convinced, but that it has been greatly overworked in our time, and that more has been put upon it than it can bear, of this also I am convinced.

I think we are safe in saying that a bird is protectively colored when the color, as it were, strikes in, and the bird itself acts upon the theory that it is in a measure hidden behind its assimilative plumage. This is true of nearly all the grouse tribe. These birds seem instinctively to know the value of their imitative tints, and are tame or wild according as their tints do or do not match the snow on the ground. Moreover the grouse are all toothsome ; and this fact of the toothsomeness of some birds and the toughness and unsavoriness of others, like the woodpecker, the crow tribe, gulls, divers, cormorants, and the like, has undoubtedly played some part in their natural history. But whether they are dull colored because they are toothsome, or toothsome because they are dull colored — who shall say ? Which was first, the sweetness or the color ? The flesh of the quail and the partridge having become very delectable and much sought after by many wild creatures, did nature make compensation by giving them their assimilative plumage ? or were the two facts inseparable from the first ?

The sweetness of an animal’s flesh is doubtless determined by its food. I believe no one eats the western road-runner, though it is duller of color than the turkey. Its food is mice, snakes, lizards, centipedes, and other vermin.

Thus far I can follow the protective colorists, but not much farther.

Wallace goes to the extent of believing that even nuts are protectively colored because they are not to be eaten. But without the agency of birds and the small rodents, the wingless nuts, such as chestnuts, acorns, hickory nuts, and butternuts, could never get widely scattered, so that if they were effectively concealed by their colors this fact would tend to their extinction.

If the colors of animals were as vital a matter, and the result of the same adaptive and selective process, as their varied structures, which Darwin and Wallace teach, then it would seem to follow that those of the same habits and of the same or similar habitat would be similar or identical in color, which is not commonly the case. Thus the waders among the birds all have long legs and long necks, but they are not all of the same color. The divers all have short legs placed far in the rear, but they vary greatly in color markings. How greatly the ducks differ in coloration, though essentially the same in structure! Our tree warblers are of all hues and combinations of hues, though so alike in habit and form. The painted bunting in the southwest is gaudily colored, while its congeners are all more plainly dressed.

In England the thrush that answers to our robin, being almost identical in form, manner, and habit, is black as a coal. The crow tribe are all built upon the same plan, and yet they show a very great diversity of colors. Why is our jay so showily colored, and the Canada jay so subdued in tint ?

The humming birds do not differ much in their anatomy, but their tints differ as much as do those of precious stones. The woodpeckers show a variety of markings that cannot be accounted for upon any principle of utility or of natural selection. Indeed, it would seem as if in the colors of birds and mammals nature gave herself a comparatively free hand, not being bound by the same rigid necessity as in their structures. Within certain limits something like caprice or accident seems to prevail. The great law of assimilation, or harmonious blending, of which I shall presently have more to say, goes on, but it is checked and thwarted and made sport of by other tendencies.

Then the principle of coloration of the same species does not always hold good in different parts of the earth. Thus our grouse and other gallinaceous birds are obscurely marked, like the ground they live upon, but in the Orient, in India and China, the allied species are brightly colored, and we have the golden pheasant, and the Argus pheasant, and others.

In our hemisphere the swans are white, the pigeons are blue, and the parrots are green. In Australia the swans are black, and there is a black pigeon and a black parrot. In the desert of Sahara most of the birds are desert-colored, but there are some that are blue, and others that are black or brown and white. It is said that the Arctic fox which is snow-white in most other places remains blue all winter in Iceland. No doubt there are reasons for all these variations, but whatever these reasons are, they do not seem to favor the theory of protective coloration.

Mr. Wallace in one of his essays points out the effect of locality on color, many species of unrelated genera both among insects and among birds being marked similarly, with white or yellow or black like the effect of some fashion that has spread among them. In the Philippine Islands metallic hues are the fashion; in some other islands very light tints are in vogue; in other localities unrelated species favor crimson or blue. Mr. Wallace says that among the different butterflies of different countries this preference for certain colors is as marked as it would be if the hares, marmots, and squirrels of Europe were all red with black feet, while the corresponding species of Central Asia were all yellow with black heads, or as it would be if our smaller mammals, the coon, the possum, the squirrels, all copied the black and white of the skunk. The reason for all this is not apparent, though Wallace thinks that some quality of the soil which effects the food may be the cause. It is like the caprice of fashion. In fact, the exaggerated plumes and bizarre colors and monstrous beaks of many birds in both hemispheres have as little apparent utility, and seem quite as much the result of caprice, as are any of the extreme fashions in dress among human beings.

Most of our black birds flock in the fall, and they are not protectively colored, but the bobolinks, which also flock then, do then assume neutral tints. Why the change in the one case and not in the other, since both species feed in the brown marshes ? Most of our own ground birds are more or less ground colored, but here is the chewink on the ground, amid the bushes, with the brown oven bird and the brown thrasher, with conspicuous markings of white and black and red. Here are some of the soft gray and brown tinted warblers nesting on the ground, and here is the more conspicuous striped black and white creeping warbler nesting by their side. Behold the rather dull colored great crested flycatcher concealing its nest in a hollow limb, and its congener, the brighter feathered king bird, building its nest openly on the branch above.

Hence, whatever truth there may be in this theory of protective coloration, one has only to look about him to discover that it is a matter which nature does not have very much at heart, She plays fast and loose with it on every hand. Now she seems to set great store by it, the next moment she discards it entirely.

If dull colors are protective, then bright colors are non-protective or dangerous, and one wonders why all birds of gay feather have not been cut off and the species exterminated: or why, in cases where the males are bright colored and the females of neutral tints, as with our scarlet tanager, and indigo bird, the females are not greatly in excess of the males, which does not seem to be the case.

II

We arrive at the idea that neutral tints are protective from the point of view of the human eye. Now if all animals that prey upon others were guided by the eye alone there would be much more in the theory than there is. But none of the predaceous four-footed beasts depend entirely upon the eye. The cat tribe does to a certain extent, but these creatures stalk or waylay moving game, and the color does not count. A white hare will evidently fall a prey to a lynx or a cougar in our winter woods as easily as a brown rabbit; and will not a desert-colored animal fall a prey to a lion or a tiger just as readily as it would if it were white or black ? Then the most destructive tribes of all, the wolves, the foxes, the minks, the weasels, the skunks, the coons, and the like, depend entirely upon scent. The eye plays a very insignificant part in their hunting, hence again the question of color is eliminated.

Birds of prey depend upon the eye, but they are also protectively colored, and their eyes are so preternaturally sharp that no disguise of assimilative tints is of any avail against them. If both the hunted and its hunter are concealed by their neutral tints, of what advantage is it to either ? If the brown bird is hidden from the brown hawk, and vice versa, then are they on an equal footing in this respect, and the victory is to the sharpest eyed. If the eye of the hawk sharpens as the problem of his existence becomes more difficult, as is doubtless the case, then is the game even, and the quarry has no advantage, the protective color does not protect.

Why should the owl, which hunts by night, be colored like the hawk, that hunts by day ? If the owl were red, or blue, or green, or black, or white, would it not stand just as good a chance of obtaining a subsistence ? Its silent flight, its keenness of vision, and the general obscurity, are the main matters. At night color is almost neutralized. Would not the lynx and the bobcat fare just as well if they were of the hue of the sable or the mink ? Are their neutral grays or browns any advantage to them ? The gray fox is more protectively colored than the red; is he therefore more abundant ? Far from it; just the reverse is true. The same remark applies to the red and the gray squirrels.

The northern hare, which changes to white in winter, would seem to have an advantage over the little gray rabbit, which is as conspicuous upon the snow as a brown leaf, and yet such does not seem to be the case. It is true that the rabbit often passes the day in holes and beneath rocks, and the hare does not; but it is only at night that the natural enemies of each — foxes, minks, weasels, wild cats, owls — are abroad.

It is thought by Wallace and others that the skunk is strikingly marked as a danger signal, its contrast of black and white warning all creatures to pass by on the other side. But the magpie is marked in much the same way, as is also our bobolink which, in some localities, is called “the skunk bird,” and neither of these birds has any such reason to advertise itself as has the skunk. Then here is the porcupine, with its panoply of spears, as protectively colored as the coon or the woodchuck, — why does not it have warning colors also ? The enemy that attacks it fares much worse than in the case of its black and white neighbor.

The ptarmigan is often cited as a good illustration of the value of protective coloration,—white in winter, particolored in spring, and brown in summer, — always in color blending with its environment. But the Arctic fox would not be baffled by its color; it goes by scent; and the great snowy owl would probably see it in the open at any time of year. On islands in Bering Sea we saw the Arctic snow bird, white as a snowflake in midsummer, and visible afar. Our northern grouse carry their gray and brown tints through our winters, and do not appear to suffer unduly from their telltale plumage. If the cold were as severe as it is farther north, doubtless they, too, would don white coats, for the extreme cold, no doubt, plays an important part in this matter, — this and the long Arctic nights. Sir John Ross protected a Hudson’s Bay lemming from the low temperature by keeping it in his cabin, and the animal retained its summer coat; but when he exposed it to a temperature of thirty degrees below zero, it began to change to white in a single night, and at the end of a week was almost entirely so. It is said that in Siberia domestic cattle and horses become lighter colored during the winter, and Darwin says he has known in England brown ponies to become white in winter.

Only one of our weasels becomes white in winter, the ermine, the others keep their brown coats through the year. Is this adaptive color any advantage to the ermine ? and are the other weasels handicapped by their brown tints ?

The marten, the sable, and the fisher do not turn white in winter, nor the musk ox, nor the reindeer. The latter animals are gregarious, and the social spirit seems to oppose local color.

The long Arctic nights and the intense cold no doubt have much to do with the white of Arctic animals. “Absence of light leads to diminution or even total abolition of pigmentation, while its presence leads to an increase in some degree proportionate to the intensity of the light.” 1

When the variable northern hare is removed to a milder climate, in the course of a few years it ceases to turn white in winter.

The more local an animal is, the more does it incline to take on the colors of its surroundings, as may be seen in the case of the toads, the frogs, the snakes, and many insects. It seems reasonable that the influence of the environment should be more potent in such cases. The grasshoppers in the fields are of all shades of green and brown and gray, but is it probable that these tints ever hide them from their natural enemies — the sharpeyed birds and fowls ? A grasshopper gives itself away when it hops, and it always hops.

On the sea coast I noticed that the grasshoppers were gray like the sands. What fed upon them, if anything, I could not find out, but their incessant hopping showed how little they sought concealment. The nocturnal enemies of grasshoppers, such as coons and skunks, are probably not baffled at all by their assimilative colors.

Our wood frog, rana sylvaticus, is found throughout the summer on the dry leaves in the woods, and it is red like them. When it buries itself in the leaf mould in the fall for its winter hibernation, it turns dark like the color of the element in which it is buried. Can this last change be for protection also ? No enemy sees it or disturbs it in that position, and yet it is as “protectively” colored as in summer. This is the stamp of the environment again.

The toad is of the color of the ground where he fumbles along in the twilight, or squats by day, and yet, I fancy, his enemy, the snake, finds him out without difficulty. He is of the color of the earth because he is of the earth earthy, and the bullfrog is of the color of his element, — but there is the little green frog, and the leopard, and the pickerel frogs, all quite showily marked. So there we are, trying to tabulate nature when she will not be tabulated! Whether it be the phrase protective coloration, or the imprint of the environment, with which we seek to capture her, she will not always be captured. In the tropics there are gaudily colored tree frogs, — blue,yellow, striped, — frogs with red bodies and blue legs, and these showy creatures are never preyed upon, they are uneatable. But the old question comes up again—are the colors to advertise their uneatableness, or are they the necessary outcome, and would they be the same in a world where no living thing was preyed upon by another ? The acids or juices that make their flesh unpalatable may be the same that produce the bright colors. To confound the cause with the effect is a common error. I doubt if the high color of some poisonous mushrooms is a warning color, or has any reference to outward conditions. The poison and the color are probably inseparable.

The muskrat’s color blends him with his surroundings, and yet his enemies, the mink, the fox, the otter, trail him just the same; his color does not avail. The same may be said of the woodchuck. What color could he be but earth color ? and yet the wolf and the fox smell him out just the same. If he were snow-white or jet-black (as he sometimes is) he would be in no greater danger.

I think it highly probable that our bluebird is a descendant of a thrush. The speckled breast of the young birds indicates this, as does a thrush-like note which one may occasionally hear from it. The bird departed from the protective livery of the thrush and came down its long line of descent in a showy coat of blue, and yet got on just as well as its ancestors. Gay plumes were certainly no handicap in this case. Are they in any case ? I seriously doubt it. In fact, I am inclined to think that if the birds and the mammals of the earth had been of all the colors of the rainbow, they would be just about as numerous.

The fact that this assimilative coloring disappears in the case of animals under domestication, — that the neutral grays and browns are followed by white and black and particolored animals, — what does that prove ? It proves only that the order of nature has been interfered with, and that as wild instinct becomes demoralized under domestication, so does the wild coloration of animals. The conditions are changed, a whole series of new influences are brought to bear, the food is changed and is of greater variety, climatic influences are interfered with, a great variety of new and strange impressions are made upon each individual animal, and nature abandons her uniformity of coloration and becomes reckless, so to speak, not because the pressure of danger is removed, but because the danger is of a new and incalculable kind — the danger of man and of artificial conditions. Man demoralizes nature whenever he touches her, in savage tribes and in animal life, as well as in the fields and woods. The tendency to variation is stimulated; form as well as color is rapidly modified; the old order is broken up, and the animal comes to partake more or less of his bizarre life. Man makes sharp contrasts wherever he goes, in forms, in colors, in sounds, in odors, and it is not to be wondered at that animals brought under his influence come in time to show, more or less, these contrasts. Nature when left to herself is harmonious; man makes discords, or harmony of another order. The instincts of wild animals are much more keen and invariable than are those of animals in domestication. The conditions of their lives are more rigid and exacting. Remove the eggs from a wild bird’s nest and she instantly deserts it; but a domestic fowl will incubate an empty nest for days. For the same reason the colors of animals in domestication are less constant than in the wild state ; they break up and become much more bizarre and capricious.

Cultivated plants depart more from a fixed type than plants of the fields and the woods. See what outré forms and colors the cultivated flowers display!

The pressure of fear is of course much greater upon the wild creatures than upon the tame, but that the removal or the modification of this should cause them to lose their neutral tints is not credible. The domestic pigeons and the barnyard fowls are almost as much exposed to their arch enemy, the hawk, as is the wild pigeon or the jungle fowl, if not more, as these latter have the cover of trees and woods to rush to. And what an eye these birds have for hawks, whether they circle in the air or walk about in the near fields! how ceaseless their vigilance! In fact, the instinct of fear of some enemy in the air above has apparently not been diminished in the barnyard fowls by countless generations of domestication. Let a boy shy a rusty pie-tin or his old straw hat across the henyard, and behold what a screaming and a rushing to cover there is! This ever watchful fear on the part of the domestic fowls ought to have had some effect in preserving their neutral tints, but it has not. A stronger influence has come from man’s disrupture of natural relations.

Why are ducks more variously and more brilliantly colored than geese ? I think it would be hard to name the reason. A duck seems of a more intense nature than a goose, more active, more venturesome; it takes to the bypaths as it were, while the goose keeps to a few great open highways; its range is wider, its food supply is probably more various, and hence it has greater adaptiveness and variability. The swan is still more restricted in its range and numbers than the goose, and, in our hemisphere, is snowwhite. The factor of protective coloration, so pronounced in the case of the goose, is quite ignored in the swan. Neither the goose nor the swan, so far as I know, has any winged enemies, but their eggs and young are doubtless in danger at times from foxes and wolves and water animals. The duck must have more enemies, because it is smaller and is found in more diverse and sundry places. Upon the principle that like begets like, that variety breeds variety, one would expect the ducks to be more brightly and variously colored than their larger congeners, the geese and the swans.

The favorite notion of some writers on natural history that, because animals are rendered less noticeable by being light beneath and dark above, this is a protective device, seems to me a hasty conclusion. This gradation in shading is an inevitable result of certain fixed principles. It applies to inanimate objects also. The apple on the tree and the melons in the garden are protectively shaded in the same way; they are all lighter beneath and deeper colored above. The mushrooms on the stumps and trees are brown above and white beneath. Where the light is feeblest the shade is lightest, and vice versa. The under side of a bird’s wing is, as a rule, lighter than the top side. The stronger the light, the more the pigments are developed. All fish that I am acquainted with are light beneath and dark above. If this condition helps to conceal them from their enemies, it is merely incidental, and not the result of laws working to that end.

III

“The danger of the mother bird during incubation,” is a phrase often used by Darwin and by more recent writers. This danger is the chief reason assigned for the more obscure coloring of the female among so many species. Now it would seem that the dangers of the mother bird during incubation ought to be far less than those of her more brilliantly colored mate, flitting from tree to tree and advertising his whereabouts by his calls and song, or absorbed in procuring his food, or than those of other females, flitting about exposed to the eye of every passing hawk. The life of most wild creatures is like that of a people engaged in war: enemies lurk on every hand, and the difference between the degree of danger of the sitting bird and that of its roving mate is like the difference between the wife rocking the cradle by her fireside, and her husband who is a soldier on a campaign. The mother bird is usually well hidden, and has nothing to do but to use her eyes and ears, and she usually does this to good purpose. Indeed, I believe the sitting bird is rarely destroyed. I have never known this to happen, though this fact does not prove very much. The peril is to the eggs or to the unfledged young; these cannot run or fly away. Eliminate this danger, and the numbers of our birds would probably double in a single year—this, and the danger from storms and cold. Hence the care the birds take to conceal their nests, not for the mother bird’s sake, but for the sake of the treasures which she cannot defend. In some cases she appears to offer herself an easy victim in order to lure the intruder away. She would have him see only her when she flutters, apparently disabled, over the ground. The game of concealment has failed; now she will try what feigning can do.

All the species of our birds in which the male is more brilliantly colored than the female, such as the scarlet tanager, the indigo bird, the rose-breasted grosbeak, the goldfinch, the summer tanager, the Kentucky cardinal, the blue grosbeak, build in trees or low bushes, and it seems to me that the dull tints of the female would play but little part in concealing the nest. The enemies of these birds, as of all the rest of our birds, are crows, squirrels, black snakes, jays, weasels, owls, and hawks, and have been for untold generations. Now the obscure coloring of the female would play no part in protecting her against any of these creatures. What would attract their attention would be the nest itself. The crows, the jays, the weasels, the squirrels, explore the trees looking for eggs and young birds, as doubtless the owls do by night. The mother bird flies at their approach, and leaves her eggs or young to be devoured. The sitting bird is not visible to an enemy passing in the air above, as she is hidden by the leaves. In the care of the young the male is as active and as exposed to danger as is the female, and in the case of the scarlet tanager the male seems the bolder and the more active of the two; yet the female, because of her obscure coloring, could afford to run many more chances than he.

With the ground builders the case is not much different. These birds are preyed upon by prowlers, — skunks, weasels, rats, snakes, crows, minks, foxes, and cats, — enemies that hunt at close range by night and by day and that search the ground by sight and by smell. It is not the parent bird, but the eggs and the young, that they capture. Indeed, I cannot see that the color of the sitting bird enters into the problem at all. Red or white or blue would not endanger the nest any more than the neutral grays and browns. The bobolink builds in meadows where the grass alone conceals it. That the back of the sitting bird harmonizes perfectly with the meadow bottom might make a difference to the egg collector, or to an eye a few feet above, but not to the mink, or the skunk, or the snake, or the fox, that came nosing about the very spot.

Last summer I saw where a woodcock had made her nest in a dry grassy field many yards from a swamp in the woods, which was her natural habitat. The instinct of the bird seemed to tell her that she would be less exposed to her prowling enemies in the dry open field than in the thick marshy woods, and her instinct was, no doubt, a safe guide. Her imitative color would avail her but little in either place. The same may be said of the quail and of the grouse. Their neutral tints may protect them from the human eye, but not from their natural enemies. Would the coon or the mink or the fox or the skunk be baffled by them ? Is the setter or pointer baffled ? Both the quail and the partridge in settled countries are very likely to nest along roads and paths, away from thick jungles and tangles that would afford cover to their enemies. It is their eggs and their newly hatched young that they are solicitous about. Their wings afford security to themselves. True, the sitting bird usually allows the passer-by to approach her very closely, but I have reason to believe that she is much sooner alarmed by an animal that approaches stealthily, nosing about, making very little noise, than by the passing of a person or of the large grazing animals. Her old traditional enemies are stealthy and subtle, and her instinct keeps her on her guard against them. One can pass within a few yards of a partridge on his drumming log, if he walks boldly past, occupied about his own business. But let him try to creep up on the drumming partridge, and see how wary and suspicious he is!

The female cowbird is much duller in color than the male, and yet she is a parasitical bird, and does no incubating at all.

A fact that seems to tell against the notions I have been advancing, and that gives support to the theory of the protective value of dull colors, is the fact that with those species of birds in which both sexes are brightly colored, the nest is usually placed in a hole, or is domed, thus concealing the sitting bird. This is true of a large number of species, as the bluebird, the woodpeckers, the chickadee, the nuthatch, the kingfisher, and, in the tropics, the many species of parrots and parrakeets and many others, all birds of brilliant plumage, the sexes being in each case indistinguishable. But there are such marked exceptions to this rule that, it seems to me, its force is greatly weakened. Our blue jay is a highly colored bird, and yet it builds an open nest. The crow builds an open nest. The passenger pigeon was a bird of rather showy colors, and the male did his share of the incubating, and the nest was built openly. The shrike is a conspicuously marked bird, and it builds an open nest. Mr. Wallace names four other brilliant old-world birds that build open nests. Then there are several species of birds, in which the female is obscurely marked, that build in holes and cavities, such as our wrens, the great crested flycatcher, the European starling, the English sparrow, the bushtits of California, and the wood duck. The female oriole is much duller colored than her mate, yet she builds a pocket nest. Of course these last cases do not prove that there is not greater safety in a hidden nest, they only show that the color of the mother bird is not the main factor in the problem. But that a bird in a hole is safer than a bird in an open nest may well be doubted. The eggs are probably more secure from the thievish crow and the blue jay, but not from rats and squirrels and weasels. I know that the bluebird and the chickadee are often broken up by some small enemy.

We fancy that the birds are guided by their instinct for protective colors in the materials they choose for their nests. Most birds certainly aim to conceal their nests — the solitary builders, but not those that nest in communities, like the cliff swallows and rooks and flamingoes— and the materials they use favor this concealment. But what other materials could they use ? They choose the material everywhere near at hand,—moss, leaves, dry grass, twigs, mud, and the like. The ground builders scrape together a few dry straws and spears of grass; the tree builders, twigs and lichens and cotton and rootlets and other dry wood products. There is nothing else for them to use. If a man builds a hut or a shanty in the fields or woods with such material as he finds ready at hand, his habitation will be protectively colored also. The winter wren builds its mouselike nest of green moss, but in every case that has come under my observation the nest was absolutely hidden by its position under a log or in a stump, or amid the roots of trees, and the most conspicuous colors would not have betrayed it to its enemies. In fact, the birds that build hidden nests in holes or tree cavities use of necessity the same neutral materials as those that build openly.

Birds that deliberately face the exterior of their nests with lichens obtained from rocks and trees, such as the humming bird, the blue-gray gnat-catcher, and the wood pewee, can hardly do so with a view to protection, because the material of their nests is already weather-worn and inconspicuous. The lichens certainly give it an artistic finish and make it a part of the branch upon which it is placed, to an extent that suggests something like taste in the builders. But I fail to see how a marauding crow, or a jay, or a squirrel, or a weasel, or any other enemy of the bird, would be cheated by this device.

IV

I find myself less inclined to look upon the neutral grays and browns of the animal world as the result of the struggle for existence, but more disposed to regard them as the result of the same law or tendency that makes nature in general adaptive and harmonious; the outcome of the blendings, the adjustments, the unifying processes, or tendencies, that are seen and felt all about us. Is not openair nature ever striving toward a deeper harmony and unity ? Do not differences, discrepancies, antagonisms, tend to disappear ? Is there not everywhere something at work to bring about agreements, correspondencies, adaptations ? to tone down contrasts, to soften outlines, to modify the abrupt, to make peace between opposites ? Is not the very condition of life and well-being involved in this principle? The abrupt, the disjoined, the irreconcilable, mean strife and dissolution, while agreements, gradations, easy transitions, mean life and growth. Like tends to beget like; the hand is subdued to the element it works in. The environment sets its stamp more or less strongly upon all living things. Even the pyramids are the color of the sands. Leave your bones there, and they will soon be of the same tint. Even your old boots or old coat will in time come to blend a little with the desert.

The tendency in nature that is over all and under all is the tendency or effort toward harmony — to get rid of strife, discord, violent contrasts, and to adjust every creature to its environment. Inside of this great law or tendency are the lesser laws of change, variety, opposition, contrast. Life must go on, and life for the moment breaks the unity, the balance. May not what is called protective coloration be largely this stamp of the environment, this tendency to oneness, to harmony and simplicity, that pervades nature, organic no less than inorganic ?

Things in nature blend and harmonize, one thing matches with another. All open-air objects tend to take on the same color tones, every thing in the woods becomes woodsy, things upon the shore get the imprint of the shore, things in the water assume the hues of the water, the lichen matches the rock and the trees, the shell matches the beach and the waves; everywhere is the tendency to unity and simplicity, to low tones and adaptive colors.

One would not expect animals of the plains or of the desert to be colored like those of the bush or of the woods; the effects of the strong uniform light in the one case and of the broken and checkered light in the other would surely result in different coloration. That never-ending brown or gray or white should not in time stamp itself upon the creatures living in the midst of it is incredible.

Through the action of this principle, water animals will be water-colored, the fish in tropic seas will be more brilliantly colored than those in northern seas, tropic birds and insects will be of gayer hues than those of the temperate zones, shore birds will be shore-tinted, Arctic life will blend more or less with Arctic snows, ground animals will assimilate to the ground colors, tree animals will show greater variety in tint and form, plains animals will be dull of hue like the plains, — all this, as I fancy, not primarily for protection or concealment, but through the law of natural assimilation, like begetting like, variety breeding variety.

What more natural than that strictly wood birds should be of many colors and shades, to be in keeping with their surroundings ? Will not the play of light and shade, the multiplicity of forms, and the ever moving leaves, come in time to have their due effect ? Will not a variety of influences tend to produce a variety of results ? Will not sameness breed sameness? Would not one expect the humming birds to be more brilliant than the warblers, and the warblers more varied in color than the finches ? the insect feeders than the seed eaters ? The humming birds are, as it were, begotten by the flowers and the sunshine, as the albatross is begotten by the sea, and the whippoorwill by the dusk. The rat will not be as bright of tint as the squirrel, nor the rabbit as the fox.

In the spring one may sometimes see a bluebird or redbird or bright warbler for a moment upon the ground. How artificial and accidental it looks, like a piece of ribbon or a bit of millinery dropped there! It is not one with the ground, it is not at home there. In the tree it is more in keeping with the changing forms and the sharper contrasts.

The environment is potent in many ways. Everything is modified by the company it keeps. Do not the quiet tints and sounds of the country have their effect upon the health and character of the dwellers there ? The citizen differs in look and manner from the countryman, the lawyer from the preacher and the doctor, the seaman from the landsman, the hermit from the cosmopolite. There is the rural dullness, and there is the metropolitan alertness. Local color, local quality, are realities. States, cities, neighborhoods, have shades of difference in speech and manner. The less traveled a people are, the more marked these differences appear. The more a man stays at home, the more the stamp of his environment is upon him. The more limited the range of an animal, the more it is modified by its immediate surroundings. Thus the loon is so much of a water bird that it can only hobble upon the land, and the swallow is so much a creature of the air that its feet are of little use to it. Perfect adaptability usually narrows the range, as the skater is at home only upon the ice.

Here are two closely related birds of ours, the oven bird and the water thrush, both with speckled breasts, but each tinted more or less like the ground it walks upon, the one like the dry leaves, the other like the brook stones and pond margins. The law of assimilation and of local color has done its perfect work. Were the two birds to change places, each retaining its own color, I do not believe they would be in any more jeopardy than they are now.

The camel is of a uniform gray like the desert where it is at home, while the camelopard or giraffe, a creature of the trees, is dappled or spotted. Is the color in either case protective ? Against what ? Their natural enemies could be only the larger carnivora, tigers and lions, and would they not trail them or scent them on the breeze ?

The lion is desert-colored too. Is this for concealment from its prey ? But it is said that horses and oxen scent the lion long before they can see him, as doubtless do the wild creatures of the desert upon which he feeds. Their scent would surely be keener than that of our domesticated animals, and to capture them he must run them down or ambush them where the wind favors him. His desert color is the brand of his environment. If his home were the rocks or the mountains, his color would certainly be different. Nothing could be duller or more neutral than the color of the elephant, and surely he is not hiding from any natural enemy, or stalking any game.

The bright colors of many tropical fish, such as the angel fish, seem only a reflection of the bright element in which they live. The changing brilliant hues of tropic seas are expressed in the animal life in them. It is highly improbable that this is for protection; it is the law of assimilation working in the deep. All life in the tropics is marked by greater eccentricity of form and richness of coloring than in the temperate zones, and this is in keeping with the above principle.

VI

It seems to me that the question that enters most deeply into the life problem of an animal is the question of food and climate, and of climate only so far as it affects the food supply. Many of our migrating birds will brave our northern winters if they can get anything to eat. A few years ago our bluebirds in the eastern part of the continent were fearfully decimated by a cold wave and an ice storm in the South that cut off their food supply. For two or three years rarely was a bluebird seen in those parts of the country where, before the event, they had been abundant. Then they began to reappear, and now, it seems to me, there are more bluebirds than ever before. Evidently their bright colors have not stood in the way of their increase. If they have now reached their limit, it is because they have reached the limit of their food supply and their nesting sites.

How abundant are the robins everywhere, how noisy, how conspicuous! I do not doubt in the least that if, retaining their same habits, they were scarlet, or white, or indigo, they would be just as numerous as they are now. The robin is a wide, free feeder, boring in the turf for grubs and worms in summer, and taking up with cedar berries and hard-hack drupes in winter. If a crop of locusts come in cherry time, he will spare your cherries. If a drouth drives the angleworms deep into the ground in August, look out for your grapes. The robin is wonderfully adaptive. If he does not find a tree to his liking, he will nest on the wall, or under your porch, or even on the ground. His colors are not brilliant, but the secret of his success lies in his courage, his force of character, so to speak, and his adaptability. His European cousin, the blackbird, is less protectively colored, but is of similar habits and disposition, and seems to thrive equally well. Again, contrast the Baltimore oriole with the orchard oriole. If there is anything in protective color, the more soberly colored bird has greatly the advantage, and yet the more brilliant species is far more abundant. The strong contrast of black and orange which the brilliant coats present does not seem to have lessened their wearers’ chances of survival. Their pendent nests, beyond the reach of weasels and squirrels and snakes and crows, are no doubt greatly in their favor, but still more so, I believe, are their feeding habits. Compared with the orchard oriole they are miscellaneous feeders; insects and fruit and even green peas are in their bill of fare. When a bird like the orchard oriole is restricted in its range, it is quite certain that its food supply is equally restricted.

Of birds that live upon tree trunks, here are two of similar habits, one protectively colored and the other not, and yet the one that is not so colored, but is of bright tints, is far the more numerous. I refer to the nuthatch and the brown creeper. The creeper is so near the color of the bark of the trees upon which it feeds that one has great difficulty in seeing it, while the nuthatch in its uniform of black, white, and blue, contrasts strongly with its surroundings. The creeper works up and around the tree, rarely showing anything but its bark-colored back, while the nuthatch runs up and down and around the tree with head lifted, constantly exposing its white throat and breast. But the nuthatch is the better feeder, it eats nuts as well as the larvæ of insects, while the creeper seems limited to a minute kind of food which it obtains with that slender, curved bill. It can probe, but not break, with this instrument, and is never seen feeding upon the ground like the nuthatch. I am bound to state, however, that the latter bird has another advantage over the obscure creeper, which may offset the danger that might come to it from its brighter color, — it is more supple and alert. Its contact with the tree is like that of the rocker with the floor, while the line of the creeper’s back is more like that of the rocker reversed; it touches head and tail, and has far less freedom of movement than has the nuthatch. The head of the latter often points straight out from the tree, and the eye takes in all the surroundings to an extent that the creeper’s cannot.

Of course it is not safe to claim that one can always put his finger upon the exact thing that makes one species of birds more numerous than an allied species; the conditions of all animal life are complex, and involve many factors more or less obscure. In the present case I am only trying to point out how slight a part color seems to play in the problem, and how prominent a part food plays. Our ruffed grouse holds its own against the gunners, the trappers, the hard winters, and all its numerous natural enemies, not, I think, because it is protectively colored, but because it, too, is a miscellaneous feeder, ranging from berries and insects to buds and leaves. The quail has the same adaptive coloring, but not the same range of food supply, and hence is more easily cut off. Birds that subsist upon a great variety of foods, no matter what their coloring, apparently have the best chance of surviving.

VII

There seem to be two instincts in animal life that work against the influence of environment upon the colors of animals, or the tendency in nature to make her neutral grays and browns everywhere prevail — the male instinct of reproduction, which is preëminent, and the social or gregarious instinct, which is far less marked, but which, I am inclined to believe, has its effect.

The gregarious birds and mammals are as a rule less locally colored than those of solitary habits. Thus the more gregarious elk and antelope and sheep are less adaptively colored than the more solitary deer. The buffalo had not the usual color of a plains animal; the individual was lost in the mass, and the mass darkened the earth. The musk ox goes in herds and does not put on a white coat in the subarctic regions.

Does a solitary life tend to beget neutral and obscure tints in a bird or beast ? The flocking birds nearly all tend to bright colors, at least brighter than their solitary congeners. The passenger pigeon furnished a good example near at hand. Contrast its bright hues with those of the more recluse turtledove. Most of our blackbirds have a strong flocking instinct, and they are conspicuously colored. The sociability of the cedar birds may help account for their crests, their banded tails, and pure, fine browns. As soon as any of the ground birds show a development of the flocking instinct their hues become more noticeable, as is the case with the junco, the snow bunting, the shore lark, and the lark bunting of the West. Among the tree fringillidœ the same tendency may be noticed; the flocking crossbills, pinegrosbeaks, redpolls, and the like, all being brighter of color than the solitary sparrows. The robin is the most social of our thrushes, and is the brightest colored.

In the tropics the parrots and parrakeets and macaws are all strikingly colored, and are all very social. Why should not this be so ? Numbers beget warmth and enthusiasm. A multitude is gay of spirit. It is always more noisy and hilarious, more festive and playful, than are single individuals. Each member is less a part of its surroundings and more a part of the flock or the herd. Its associations with nature are less intimate than with its own kind. Sociability, with the human species, tends to express itself in outward symbols and decorations, and why may not the brighter colors of the social birds be the outward expression of the same spirit ?

The social flamingo does not, in the matter of color, seem to have been influenced by its environment at all. The gregarious instinct is evidently very strong in the species. Mr. Frank Chapman found them in the Bahamas living and breeding in great colonies; he discovered what he calls a flamingo city. The birds all moved and acted in concert. Their numbers showed in the distance like an army of red coats; they made the land pink. They were adapted to their marsh life by their long legs, and to the food they ate by their bills, but their colors contrasted strongly with their surroundings. The community spirit carried things with a high hand. The same is in a measure true of the ibex, the stork, the crane, — all birds more or less gregarious, and all birds of more or less gay plumes. But our solitary great blue heron, lone watcher in marshes and by pond and river margins, is obscurely colored, as is the equally solitary little green heron.

Our blue heron will stand for hours at a time on the margin of some lake or pond, or on the top of some forest tree near the water, and the eye might easily mistake him for some inanimate object. He has watched among roots and snags and dead treetops so long that he has naturally come to look like these things. What his enemies are, that he should need to hide from them, other than the fool with the gun, I do not know.

Among gregarious mammals the same spirit seems at work to check or modify the influence of the environment.

The common crow illustrates the same spirit in a wider field. The crow is a citizen of the world, he is at home everywhere, but in the matter of color he is at home nowhere. His jet black gives him away at all times and in all places. His great cunning and suspicion — whence do they come ? From his experiences with man ?

I do not know that there is very much in this idea as to the effect of the social instinct upon the colors of animals. I only throw it out as a suggestion.

But when we come to the reproductive principle or instinct, then do we strike a dominating influence; then is there contrast and excess and riot; then are there positive colors and showy ornaments; then are there bright flowers, red, orange, white, blue; then are there gaudy plumes of birds, and obtrusive forms and appendages in mammals. The old modesty and moderation of nature are abandoned. It is not now a question of harmony and quietude, but of continuing the species. Masses of color appear in the landscape; silent animals become noisy; birds burst into song, or strut and dance and pose before one another; the marshes are vocal; hawks scream and soar; a kind of madness seizes all forms of life; the quail whistles; the grouse drums in the woods, or booms upon the prairie; the shell fish in the sea, and the dull turtle upon the land, feel the new impulse that thrills through nature. The carnival of the propagating instinct is at hand. For this, and begotten by this, are the gaudy colors and the beautiful and the grotesque ornaments.

As a rule, the females are not implicated in this movement or craze to the extent that the males are. Even among the flowering plants and trees in which the two sexes are separated, the male is showy while the female is inconspicuous. The pollen-yielding catkins of the hazel and of the hickory and oak flaunt in the wind, seen by all passers, while the minute fruit-producing flower is seen by none. Nature always keeps nearer to her low tones, to her neutral ground, in the female than in the male; the female is nearer the neuter gender than is the male. She is negative when he is positive; she is more like the quiet color tones in nature, she represents the great home-staying, conservative, brooding mother principle that pervades the universe. Harmony, repose, flowing lines, subdued colors, are less the gift of the aggressive, warring masculine element than of the withdrawing and gentle feminine element. The earth is our mother, the sun is our father, is a feeling as old as the human race, and throughout the animal world the neutral and negative character of the one and the color and excess of the other still mark the two sexes. Why in the human species the woman runs more to the ornate and the superfluous than the man is a question which no doubt involves sociological considerations that are foreign to my subject.

Darwin accounts for the wide departure from the principle of utility and of protective coloration in the forms and colors of so many birds and mammals, upon his theory of sexual selection, or the preference of the female for bright colors and odd forms. Wallace rejects this theory, and attributes these things to the more robust health and vigor of the males. But in the matter of health the females of all species seem on a par with the males, though in many cases the males are the larger and the more powerful. But among our familiar birds, when the two sexes differ in color, the brighter plumaged male is no larger or more vigorous than the female.

The principle to which I have referred seems to me adequate to account for these gay plumes and fantastic forms — the male sexual principle, the positive, aggressive instinct of reproduction, always so much more active in the male than in the female; an instinct or passion that banishes fear, prudence, cunning, that makes the timid bold, the sluggish active, that runs to all sorts of excesses, that sharpens the senses, that quickens the pulse, that holds in abeyance hunger, and even the instinct of self-preservation, that arms for battle and sounds forth the call, and sows contention and strife everywhere; the principle that gives the beard to the man, the mane to the lion, the antlers to the stag, the tusks to the elephant, and — why not ? — the gorgeous plumes and bright colors to the male birds of so many species. The one thing that nature seems to have most at heart is reproduction; she will sacrifice almost everything else to this — the species must be perpetuated at all hazards, and she has, as a rule, laid the emphasis upon the male. The male in the human species is positive, or plus, where the female is negative. The life of the female among the lower animals runs more smoothly and evenly — is more on the order of the neutral tint — than is that of the male. The females of the same group differ from one another much less than do the males. The male carries a commission that makes him more restless, feverish, and pugnacious. He is literally “spoiling for a fight” most of the time. This surplusage, these loaded dice, make the game pretty sure.

Cut off the ugly bull’s horns, and you have tamed him. Castration tames him still more, and changes his whole growth and development, making him approximate in form and disposition to the female. I fancy that the same treatment would have the same effect upon the peacock, or the bird of paradise, or any other bird of fantastic plumage and high color. Destroy the power of reproduction, and the whole masculine fabric of pride, prowess, weapons and badges,gay plumes, and decorations, falls into ruins.

When we remember how inattentive and indifferent the females of all species of birds are to the displays of the males before them, it is incredible that their taste in fashions, their preferences for the gay and the ornate, should have played any considerable part in superinducing these things.

Darwin traces with great skill the gradual development of the ball and socket ocilli in the plumage of the Argus pheasant. It was evidently along, slow process. Is it credible that the female observed and appreciated each successive slight change in the growth of these spots, selecting those males in which the changes were most marked, and rejecting the others ? How could she be so influenced by changes so slight and so gradual that only a trained eye would be likely to take note of them ? It is imputing to the female a degree of taste and a power of discrimination that are found only in man. Why, then, it may be asked, is the male so active in showing off his finery before the female ? Of course it is to move her, to excite her to the point of mating with him. His gay plumes are the badge of his masculinity, and it is to his masculinity that her feminine nature responds. She is aroused when he brings to bear upon her all the batteries of his male sex. She is negative at the start, as he is positive. She must be warmed up, and it is his function to do it. She does not select, she accepts, or rejects. The male does the selecting. He offers himself, and she refuses or agrees, but the initiative is with him always. He would doubtless strut just the same were there no hens around. He struts because he has to, because strutting is the outward expression of his feelings. The presence of the hen no doubt aggravates the feeling, and her response is a reaction to the stimuli he offers, just as his own struttings are reactions to the internal stimuli that are at the time governing him. In the Zoo at the Bronx the peacock has been seen to strut before a crow.

Undoubtedly the males in whom the masculine principle is the strongest and most masterful are most acceptable to the females, and the marvelous development of form and color in the peacock, or in the Argus pheasant, might take place under the stimulus of continued success. If there are two rival cocks in the yard, the hens will, as a rule, prefer the victor, — the one that struts the most and crows the loudest. How amusing to see the defeated cock fold his wings, depress his plumage, and look as unpretentious and henlike as possible in the presence of his master!

If the male bird sang only while courting the female, we might think he sang only to excite her admiration, but he continues to sing until the young appear, and, fitfully, long after that, his bright colors in many cases gradually disappearing with his declining song impulse, and both fading out as the sexual instinct has run its course. It was the sexual impulse that called them into being, and they decline as it declines. It is this impulse that makes all male birds so pugnacious during the breeding season. A brighter iris not only comes upon the burnished dove in the spring, but also a warmer glow comes upon the robin’s breast, and the hues of all other male birds are more or less deepened and intensified at this time.

The odd forms and bizarre colors that so often prevail among birds, more especially tropical and semi-tropical birds, and among insects, suggest fashions among men, capricious, fantastic, gaudy, often grotesque, and having no direct reference to the needs of the creatures possessing them. They are clearly the riot and overflow of the male sexual principle, — the carnival of the nuptial and breeding impulse. The cock or sham nests of the male wrens seem to be the result of the excess and overflow of the same principle.

It is not, therefore, in my view of the case, female selection that gives the males their bright plumage, but the inborn tendency of the masculine principle to riot and overplus. There is, strictly speaking, no wooing, no courtship, among the fourfooted beasts, and yet the badges of masculinity, manes, horns, tusks, pride, pugnacity, are as pronounced here as are the male adornments among the fowls of the air.

Why, among the polygamous species of birds, are the males so much more strongly marked than among the monogamous ? Why, but as a result of the superabundance and riot of the male sexual principle ? In some cases among the quadrupeds it even greatly increases the size of the males over the females, as among the polygamous fur seals.

Darwin came very near to the key of the problem he was looking for when he said that the reason why, throughout the animal kingdom, when the sexes differ in external appearance, the male has been the more modified, is that “the males of almost all animals have stronger passions than the females.”

“In mankind, and even as low down in the scale as in the Lepidoptera, the temperature of the body is higher in the male than in the female.” (Darwin.)

If the female refuses the male, it is not because he does not fill her eye or arouse her admiration, but because the mating instinct is not yet ripe. The males among nearly all our birds fairly thrust themselves upon the females, and carry them by storm. This may be seen almost any spring day in the squabbles of the English sparrows along the street. The female appears to resist all her suitors, defending herself against them by thrusting spitefully right and left, and just what decides her finally to mate with any one of them is a puzzle. It may be stated as a general rule that all females are reluctant or negative, and all males are eager or positive, and that the male wins, not through the taste of the female, — her love for bright colors and ornamental appendages, — but through the dominance of his own masculinity. He is the stronger force, he is aggressive and persuasive, and finally kindles her with his own breeding instinct.

Even among creatures so low in the scale of life as the crab, the males of certain species, during the breeding season, dance and gyrate about the females, assuming many grotesque postures and behaving as if intoxicated — as, indeed, they are, with the breeding passion.

Evidently the female crab does not prefer one male over another, but mates with the one that offers himself as soon as he has excited her to the mating point. And I have no proof that among the birds the female ever shows preference for one male over another; she must be won, of course, and she is won when the male has sufficiently aroused her; she does not choose a mate, but accepts one at the right time. I have seen two male bluebirds fight for hours over a female, while she sat and looked on indifferently. And I have seen two females fight over a male, while he sat and looked on indifferently. “Either will suit, but I want but one.”

Of course, nature does not work as man works. Our notions of prudence, of precision, of rule and measure, are foreign to her ways. The stakes are hers, whoever wins. She works by no inflexible system or plan, she is spontaneous and variable every moment. She heaps the measure, or she scants the measure, and it is all one to her. Our easy explanations of her ways, — how often they leave us where they found us! The balance of life upon the globe is fairly well maintained by checks and counter checks, by some species being prolific and other species less so, by the development of assimilative colors by one kind, and of showy colors by another, by slow but ceaseless modifications and adaptations. It is a problem of many and complex factors, in which, no doubt, color plays its part, but, I believe, this part is a minor one.

  1. Vernon on Variation in Animals and Plants.