Ways of Nature Part 11

In view of the ignorance of birds with regard to strings, how can we credit the story told by one of our popular nature writers of a pair of orioles that deliberately impaled a piece of cloth upon a thorn in order that it might be held firmly while they pulled out the threads?

When it came loose, they refastened it. The story is incredible for two reasons: (1) the male oriole does not a.s.sist the female in building the nest; he only furnishes the music; (2) the whole proceeding implies an amount of reflection and skill in dealing with a new problem that none of our birds possess. What experience has the race of orioles had with cloth, that any member of it should know how to unravel it in that way? The whole idea is absurd.

IV. MIMICRY

To what lengths the protective resemblance theory is pushed by some of its expounders! Thus, in the neighborhood of Rio Janeiro there are two species of hawks that closely resemble each other, but one eats only insects and the other eats birds. Mr. Wallace thinks that the bird-eater mimics the insect-eater, so as to deceive the birds, which are not afraid of the latter. But if the two hawks look alike, would not the birds come to regard them both as bird-eaters, since one of them does eat birds? Would they not at once identify the harmless one with their real enemy and thus fear them both alike? If the latter were newcomers and vastly in the minority, then the ruse might work for a while. But if there were ten harmless hawks around to one dangerous one, the former would quickly suffer from the character of the latter in the estimation of the birds. Birds are instinctively afraid of all hawk kind.

Wallace thinks it may be an advantage to cuckoos, a rather feeble cla.s.s of birds, to resemble the hawks, but this seems to me far-fetched. True it is, if the sheep could imitate the wolf, its enemies might keep clear of it. Why, then, has not this resemblance been brought about? Our cuckoo is a feeble and defenseless bird also, but it bears no resemblance to the hawk. The same can be said of scores of other birds.

Many of these close resemblances among different species of animals are no doubt purely accidental, or the result of the same law of variation acting under similar conditions. We have a hummingbird moth that so closely in its form and flight and manner resembles a hummingbird, that if this resemblance brought it any immunity from danger it would be set down as a clear case of mimicry. There is such a moth in England, too, where no hummingbird is found. Why should not Nature repeat herself in this way? This moth feeds upon the nectar of flowers like the hummingbird, and why should it not have the hummingbird's form and manner?

Then there are accidental resemblances in nature, such as the often-seen resemblance of knots of trees and of vegetables to the human form, and of a certain fungus to a part of man's anatomy. We have a fly that resembles a honey-bee. In my bee-hunting days I used to call it the "mock honey-bee." It would come up the wind on the scent of my bee box and hum about it precisely like a real bee. Of course it was here before the honey-bee, and has been evolved quite independently of it. It feeds upon the pollen and nectar of flowers like the true bee, and is, therefore, of similar form and color. The honey-bee has its enemies; the toads and tree-frogs feed upon it, and the kingbird captures the slow drone.

When an edible b.u.t.terfly mimics an inedible or noxious one, as is frequently the case in the tropics, the mimicker is no doubt the gainer.

It makes a big difference whether the mimicker is seeking to escape from an enemy, or seeking to deceive its prey. I fail to see how, in the latter case, any disguise of form or color could be brought about.

Our shrike, at times, murders little birds and eats out their brains, and it has not the form, or the color, or the eye of a bird of prey, and thus probably deceives its victims, but there is no reason to believe that this guise is the result of any sort of mimicry.

V. THE COLORS OF FRUITS

Mr. Wallace even looks upon the nuts as protectively colored, because they are not to be eaten. But without the agency of the birds and the squirrels, how are the heavy nuts, such as the chestnut, beechnut, acorn, b.u.t.ternut, and the like, to be scattered? The blue jay is often busy hours at a time in the fall, planting chestnuts and acorns, and red squirrels carry b.u.t.ternuts and walnuts far from the parent trees, and place them in forked limbs and holes for future use. Of course, many of these fall to the ground and take root. If the protective coloration of the nuts, then, were effective, it would defeat a purpose which every tree and shrub and plant has at heart, namely, the scattering of its seed. I notice that the b.u.t.ton-b.a.l.l.s on the sycamores are protectively colored also, and certainly they do not crave concealment. It is true that they hang on the naked trees till spring, when no concealment is possible. It is also true that the jays and the crows carry away the chestnuts from the open burrs on the trees where no color scheme would conceal them. But the squirrels find them upon the ground even beneath the snow, being guided, no doubt, by the sense of smell.

The hickory nut is almost white; why does it not seek concealment also? It is just as helpless as the others, and is just as sweet-meated. It occurs to me that birds can do nothing with it on account of its thick sh.e.l.l; it needs, therefore, to attract some four-footed creature that will carry it away from the parent tree, and this is done by the mice and the squirrels. But if this is the reason of its whiteness, there is the dusky b.u.t.ternut and the black walnut, both more or less concealed by their color, and yet having the same need of some creature to scatter them.

The seeds of the maple, and of the ash and the linden, are obscurely colored, and they are winged; hence they do not need the aid of any creature in their dissemination. To say that this is the reason of their dull, unattractive tints would be an explanation on a par with much that one hears about the significance of animal and vegetable coloration. Why is corn so bright colored, and wheat and barley so dull, and rice so white? No doubt there is a reason in each case, but I doubt if that reason has any relation to the surrounding animal life.

The new Botany teaches that the flowers have color and perfume to attract the insects to aid in their fertilization--a need so paramount with all plants, because plants that are fertilized by aid of the wind have very inconspicuous flowers. Is it equally true that the high color of most fruits is to attract some hungry creature to come and eat them and thus scatter the seeds? From the dwarf cornel, or bunch-berry, in the woods, to the red thorn in the fields, every fruit-bearing plant and shrub and tree seems to advertise itself to the pa.s.ser-by in its bright hues. Apparently there is no other use to the plant of the fleshy pericarp than to serve as a bait or wage for some animal to come and sow its seed. Why, then, should it not take on these alluring colors to help along this end? And yet there comes the thought, may not this scarlet and gold of the berries and tree fruits be the inevitable result of the chemistry of ripening, as it is with the autumn foliage? What benefit to the tree, directly or indirectly, is all this wealth of color of the autumn? Many of the toadstools are highly colored also; how do they profit by it? Many of the sh.e.l.ls upon the beach are very showy; to what end? The cherry-birds find the pale ox-hearts as readily as they do the brilliant Murillos, and the dull blue cedar berries and the duller drupes of the lotus are not concealed from them nor from the robins. But it is true that the greenish white grapes in the vineyard do not suffer from the attacks of the birds as do the blue and red ones. The reason probably is that the birds regard them as unripe. The white grape is quite recent, and the birds have not yet "caught on."

Poisonous fruits are also highly colored; to what end? In Bermuda I saw on low bushes great ma.s.ses of what they called "pigeon-berries" of a brilliant yellow color and very tempting, yet I was a.s.sured they were poisonous. It would be interesting to know if anything eats the red berries of our wild turnip or arum. I doubt if any bird or beast could stand them. Wherefore, then, are they so brightly colored? I am also equally curious to know if anything eats the fruit of the red and white baneberry and the blue cohosh.

The seeds of some wild fruit, such as the climbing bitter-sweet, are so soft that it seems impossible they should pa.s.s through the gizzard of a bird and not be destroyed.

The fruit of the sumac comes the nearest to being a cheat of anything I know of in nature--a collection of seeds covered with a flannel coat with just a perceptible acid taste, and all highly colored. Unless the seed itself is digested, what is there to tempt the bird to devour it, or to reward it for so doing?

In the tropics one sees fruits that do not become bright colored on ripening, such as the breadfruit, the custard apple, the naseberry, the mango. And tropical foliage never colors up as does the foliage of northern trees.

VI. INSTINCT

Many false notions seem to be current in the popular mind about instinct. Apparently, some of our writers on natural history themes would like to discard the word entirely. Now instinct is not opposed to intelligence; it is intelligence of the unlearned, unconscious kind,--the intelligence innate in nature. We use the word to distinguish a gift or faculty which animals possess, and which is independent of instruction and experience, from the mental equipment of man which depends mainly upon instruction and experience. A man has to be taught to do that which the lower animals do from nature. Hence the animals do not progress in knowledge, while man's progress is almost limitless. A man is an animal born again into a higher spiritual plane. He has lost or shed many of his animal instincts in the process, but he has gained the capacity for great and wonderful improvement.

Instinct is opposed to reason, to reflection, to thought,--to that kind of intelligence which knows and takes cognizance of itself.

Instinct is that lower form of intelligence which acts through the senses,--sense perception, sense a.s.sociation, sense memory,--which we share with the animals, though their eyes and ears and noses are often quicker and keener than ours. Hence the animals know only the present, visible, objective world, while man through his gift of reason and thought knows the inward world of ideas and ideal relations.

An animal for the most part knows all that it is necessary for it to know as soon as it reaches maturity; what it learns beyond that, what it learns at the hands of the animal-trainer, for instance, it learns slowly, through a long repet.i.tion of the process of trial and failure. Man also achieves many things through practice alone, or through the same process of trial and failure. Much of his manual skill comes in this way, but he learns certain things through the exercise of his reason; he sees how the thing is done, and the relation of the elements of the problem to one another. The trained animal never sees _how_ the thing is done, it simply does it automatically, because certain sense impressions have been stamped upon it till a habit has been formed, just as a man will often wind his watch before going to bed, or do some other accustomed act, without thinking of it.

The bird builds her nest and builds it intelligently, that is, she adapts means to an end; but there is no reason to suppose that she _thinks_ about it in the sense that man does when he builds his house.

The nest-building instinct is stimulated into activity by outward conditions of place and climate and food supply as truly as the growth of a plant is thus stimulated.

As I look upon the matter, the most wonderful and ingenious nests in the world, as those of the weaver-birds and orioles, show no more independent self-directed and self-originated thought than does the rude nest of the pigeon or the cuckoo. They evince a higher grade of intelligent instinct, and that is all. Both are equally the result of natural promptings, and not of acquired skill, or the lack of it. One species of bird will occasionally learn the song of another species, but the song impulse must be there to begin with, and this must be stimulated in the right way at the right time. A caged English sparrow has been known to learn the song of the canary caged with or near it, but the sparrow certainly inherits the song impulse. One has proof of this when he hears a company of these sparrows sitting in a tree in spring chattering and chirping in unison, and almost reaching an utterance that is song-like. Our cedar-bird does not seem to have the song impulse, and I doubt if it could ever be taught to sing. In like manner our ruffed grouse has but feeble vocal powers, and I do not suppose it would learn to crow or cackle if brought up in the barn-yard. It expresses its joy at the return of spring and the mating season in its drum, as do the woodp.e.c.k.e.rs.

The recent English writer Richard Kearton says there is "no such dead level of unreasoning instinct" in the animal world as is popularly supposed, and he seems to base the remark upon the fact that he found certain of the cavities or holes in a hay-rick where sparrows roosted lined with feathers, while others were not lined. Such departures from a level line of habit as this are common enough among all creatures.

Instinct is not something as rigid as cast iron; it does not invariably act like a machine, always the same. The animal is something alive, and is subject to the law of variation. Instinct may act more strongly in one kind than in another, just as reason may act more strongly in one man than in another, or as one animal may have greater speed or courage than another of the same species. It would be hard to find two live creatures, very far up in the scale, exactly alike. A thrush may use much mud in the construction of its nest, or it may use little or none at all; the oriole may weave strings into its nest, or it may use only dry gra.s.ses and horse-hairs; such cases only show variations in the action of instinct. But if an oriole should build a nest like a robin, or a robin build like a cliff swallow, that would be a departure from instinct to take note of.

Some birds show a much higher degree of variability than others; some species vary much in song, others in nesting and in feeding habits. I have never noticed much variation in the songs of robins, but in their nesting-habits they vary constantly. Thus one nest will be almost dest.i.tute of mud, while another will be composed almost mainly of mud; one will have a large ma.s.s of dry gra.s.s and weeds as its foundation, while the next one will have little or no foundation of the kind. The sites chosen vary still more, ranging from the ground all the way to the tops of trees. I have seen a robin's nest built in the centre of a small box that held a clump of ferns, which stood by the roadside on the top of a low post near a house, and without cover or s.h.i.+eld of any sort. The robin had welded her nest so completely to the soil in the box that the whole could be lifted by the rim of the nest. She had given a very pretty and unique effect to the nest by a border of fine dark rootlets skillfully woven together. The song sparrow shows a high degree of variability both in its song and in its nesting-habits, each bird having several songs of its own, while one may nest upon the ground and another in a low bush, or in the vines on the side of your house. The vesper sparrow, on the other hand, shows a much lower degree of variability, the individuals rarely differing in their songs, while all the nests I have ever found of this sparrow were in open gra.s.sy fields upon the ground. The chipping or social sparrow is usually very constant in its song and its nesting-habits, and yet one season a chippy built her nest in an old robin's nest in the vines on my porch. It was a very pretty instance of adaptation on the part of the little bird. Another chippy that I knew had an original song, one that resembled the sound of a small tin whistle. The bush sparrow, too, is pretty constant in choosing a bush in which to place its nest, yet I once found the nest of this sparrow upon the ground in an open field with suitable bushes within a few yards of it. The woodp.e.c.k.e.rs, the jays, the cuckoos, the pewees, the warblers, and other wood birds show only a low degree of variability in song, feeding, and nesting habits. The Baltimore oriole makes free use of strings in its nest-building, and the songs of different birds of this species vary greatly, while the orchard oriole makes no use of strings, so far as I have observed, and its song is always and everywhere the same. Hence we may say that the lives of some birds run much more in ruts than do those of others; they show less plasticity of instinct, and are perhaps for that reason less near the state of free intelligence.

Organic life in all its forms is flexible; instinct is flexible; the habits of all the animals change more or less with changed conditions, but the range of the fluctuations in the lives of the wild creatures is very limited, and is always determined by surrounding circ.u.mstances, and not by individual volition, as it so often is in the case of man. In a treeless country birds that sing on the perch elsewhere will sing on the wing. The black bear in the Southern States "holes up" for a much shorter period than in Canada or the Rockies.

Why is the spruce grouse so stupid compared with most other species?

Why is the Canada jay so tame and familiar about your camp in the northern woods or in the Rockies, and the other jays so wary? Such variations, of course, have their natural explanation, whatever it may be. In New Zealand there is a parrot, the kea, that once lived upon honey and fruit, but that now lives upon the sheep, tearing its way down to the kidney fat.

This is a wide departure in instinct, but it is not to be read as a development of reason in its place. It is a modified instinct,--the instinct for food seeking new sources of supply. Exactly how it came about would be interesting to know. Our oriole is an insectivorous bird, but in some localities it is very destructive in the August vineyards. It does not become a fruit-eater like the robin, but a juice-sucker; it punctures the grapes for their unfermented wine.

Here, again, we have a case of modified and adaptive instinct. All animals are more or less adaptive, and avail themselves of new sources of food supply. When the southern savannas were planted with rice, the bobolinks soon found that this food suited them. A few years ago we had a great visitation in the Hudson River Valley of crossbills from the north. They lingered till the fruit of the peach orchards had set, when they discovered that here was a new source of food supply, and they became very destructive to the promised crop by deftly cutting out the embryo peaches. All such cases show how plastic and adaptive instinct is, at least in relation to food supplies. Let me again say that instinct is native, untaught intelligence, directed outward, but never inward as in man.

VII. THE ROBIN

Probably, with us, no other bird is so closely a.s.sociated with country life as the robin; most of the time pleasantly, but for a brief season, during cherry time, unpleasantly. His life touches or mingles with ours at many points--in the dooryard, in the garden, in the orchard, along the road, in the groves, in the woods. He is everywhere except in the depths of the primitive forests, and he is always very much at home. He does not hang timidly upon the skirts of our rural life, like, say, the thrasher or the chewink; he plunges in boldly and takes his chances, and his share, and often more than his share, of whatever is going. What vigor, what cheer, how persistent, how prolific, how adaptive; pugnacious, but cheery, pilfering, but companionable!

When one first sees his ruddy breast upon the lawn in spring, or his pert form outlined against a patch of lingering snow in the brown fields, or hears his simple carol from the top of a leafless tree at sundown, what a vernal thrill it gives one! What a train of pleasant a.s.sociations is quickened into life!

What pictures he makes upon the lawn! What att.i.tudes he strikes! See him seize a worm and yank it from its burrow!

I recently observed a robin boring for grubs in a country dooryard. It is a common enough sight to witness one seize an angle-worm and drag it from its burrow in the turf, but I am not sure that I ever before saw one drill for grubs and bring the big white morsel to the surface.

The robin I am speaking of had a nest of young in a maple near by, and she worked the neighborhood very industriously for food. She would run along over the short gra.s.s after the manner of robins, stopping every few feet, her form stiff and erect. Now and then she would suddenly bend her head toward the ground and bring eye or ear for a moment to bear intently upon it. Then she would spring to boring the turf vigorously with her bill, changing her att.i.tude at each stroke, alert and watchful, throwing up the gra.s.s roots and little jets of soil, stabbing deeper and deeper, growing every moment more and more excited, till finally a fat grub was seized and brought forth. Time after time, during several days, I saw her mine for grubs in this way and drag them forth. How did she know where to drill? The insect was in every case an inch below the surface. Did she hear it gnawing the roots of the gra.s.ses, or did she see a movement in the turf beneath which the grub was at work? I know not. I only know that she struck her game unerringly each time. Only twice did I see her make a few thrusts and then desist, as if she had been for the moment deceived.

How pugnacious the robin is! With what s.p.u.n.k and spirit he defends himself against his enemies! Every spring I see the robins mobbing the blue jays that go sneaking through the trees looking for eggs. The crow blackbirds nest in my evergreens, and there is perpetual war between them and the robins. The blackbirds devour the robins' eggs, and the robins never cease to utter their protest, often backing it up with blows. I saw two robins attack a young blackbird in the air, and they tweaked out his feathers at a lively rate.

One spring a pack of robins killed a cuckoo near me that they found robbing a nest. I did not witness the killing, but I have cross-questioned a number of people who did see it, and I am convinced of the fact. They set upon him when he was on the robin's nest, and left him so bruised and helpless beneath it that he soon died. It was the first intimation I had ever had that the cuckoo devoured the eggs of other birds.

Two other well-authenticated cases have come to my knowledge of robins killing cuckoos (the black-billed) in May. The robin knows its enemies, and it is quite certain, I think, that the cuckoo is one of them.

What a hustler the robin is! No wonder he gets on in the world. He is early, he is handy, he is adaptive, he is tenacious. Before the leaves are out in April the female begins her nest, concealing it as much as she can in a tree-crotch, or placing it under a shed or porch, or even under an overhanging bank upon the ground. One spring a robin built her nest upon the ladder that was hung up beneath the eaves of the wagon-shed. Having occasion to use the ladder, we placed the nest on a box that stood beneath it. The robin was disturbed at first, but soon went on with her incubating in the new and more exposed position. The same spring one built her nest upon a beam in a half-finished fruit house, going out and in through the uns.h.i.+ngled roof. One day, just as the eggs were hatched, we completed the roof, and kept up a hammering about the place till near night; the mother robin scolded a good deal, but she did not desert her young, and soon found her way in and out the door.

If a robin makes up her mind to build upon your porch, and you make up your mind that you do not want her there, there is likely to be considerable trouble on both sides before the matter is settled. The robin gets the start of you in the morning, and has her heap of dry gra.s.s and straws in place before the jealous broom is stirring, and she persists after you have cleaned out her rubbish half a dozen times. Before you have discouraged her, you may have to shunt her off of every plate or other "coign of vantage" with boards or s.h.i.+ngles. A strenuous bird indeed, and a hustler.

VIII. THE CROW

One very cold winter's morning, after a fall of nearly two feet of snow, as I came out of my door three crows were perched in an apple tree but a few rods away. One of them uttered a peculiar caw as they saw me, but they did not fly away. It was not the usual high-keyed note of alarm. It may have meant "Look out!" yet it seemed to me like the asking of alms: "Here we are, three hungry neighbors of yours; give us food." So I brought out the entrails and legs of a chicken, and placed them upon the snow. The crows very soon discovered what I had done, and with the usual suspicious movement of the closed wings which has the effect of emphasizing the birds' alertness, approached and devoured the food or carried it away. But there, was not the least strife or dispute among them over the food. Indeed, each seemed ready to give precedence to the others. In fact, the crow is a courtly, fine-mannered bird. Birds of prey will rend one another over their food; even buzzards will make some show of mauling one another with their wings; but I have yet to see anything of the kind with that gentle freebooter, the crow. Yet suspicion is his dominant trait.

Anything that looks like design puts him on his guard. The simplest device in a cornfield usually suffices to keep him away. He suspects a trap. His wit is not deep, but it is quick, and ever on the alert.

One of our natural history romancers makes the crows flock in June.

But the truth is, they do not flock till September. Through the summer the different families keep pretty well together. You may see the old ones with their young foraging about the fields, the young often being fed by their parents.

From my boyhood I have seen the yearly meeting of the crows in September or October, on a high gra.s.sy hill or a wooded ridge.

Apparently, all the crows from a large area a.s.semble at these times; you may see them coming, singly or in loose bands, from all directions to the rendezvous, till there are hundreds of them together. They make black an acre or two of ground. At intervals they all rise in the air, and wheel about, all cawing at once. Then to the ground again, or to the tree-tops, as the case may be; then, rising again, they send forth the voice of the mult.i.tude. What does it all mean? I notice that this rally is always preliminary to their going into winter quarters. It would be interesting to know just the nature of the communication that takes place between them. Not long afterwards, or early in October, they may be seen morning and evening going to and from their rookeries. The matter seems to be settled in these September gatherings of the clan. Was the spot agreed upon beforehand and notice served upon all the members of the tribe? Our "school-of-the-woods"

professors would probably infer something of the kind. I suspect it is all brought about as naturally as any other aggregation of animals. A few crows meet on the hill; they attract others and still others. The rising of a body of them in the air, the circling and cawing, may be an instinctive act to advertise the meeting to all the crows within sight or hearing. At any rate, it has this effect, and they come hurrying from all points.