Probably I have become unusually cautious of late about accepting offhand all I read in print on subjects of natural history. I take much of it with a liberal pinch of salt. Newspaper reading tends to make one cautious ­and who does not read newspapers in these days? One of my critics says, apropos of certain recent strictures of mine upon some current nature writers, that I discredit whatever I have not myself seen; that I belong to that class of observers “whose view-point is narrowed to the limit of their own personal experience.” This were a grievous fault if it were true, so much we have to take upon trust in natural history as well as in other history, and in life in general. “Mr. Burroughs might have remembered,” says another critic discussing the same subject, “that nobody has seen quite so many things as everybody.” How true! If I have ever been guilty of denying the truth of what everybody has seen, my critic has just ground for complaint. I was conscious, in the paper referred to, of denying only the truth of certain things that one man alone had reported having seen, ­things so at variance not only with my own observations, but with those of all other observers and with the fundamental principles of animal psychology, that my “will to believe,” always easy to move, balked and refused to take a step.

In matters of belief in any field, it is certain that the scientific method, the method of proof, is not of equal favor with all minds. Some persons believe what they can or must, others what they would. One person accepts what agrees with his reason and experience, another what is agreeable to his or her fancy. The grounds of probability count much with me; the tone and quality of the witness count for much. Does he ring true? Is his eye single? Does he see out of the back of his head? ­that is, does he see on more than one side of a thing? Is he in love with the truth, or with the strange, the bizarre? Last of all, my own experience comes in to correct or to modify the observations of others. If what you report is antecedently improbable, I shall want concrete proof before accepting it, and I shall cross-question your witness sharply. If you tell me you have seen apples and acorns, or pears and plums, growing upon the same tree, I shall discredit you. The thing has never been known and is contrary to nature. But if you tell me you have seen a peach tree bearing nectarines, or have known a nectarine-stone to produce a peach tree, I shall still want to cross-question you sharply, but I may believe you. Such things have happened. Or if you tell me that you have seen an old doe with horns, or a hen with spurs, or a male bird incubating and singing on the nest, unusual as the last occurrence is, I shall not dispute you. I will concede that you may have seen a white crow or a white blackbird or a white robin, or a black chipmunk or a black red squirrel, and many other departures from the usual in animal life; but I cannot share the conviction of the man who told me he had seen a red squirrel curing rye before storing it up in its den, or of the writer who believes the fox will ride upon the back of a sheep to escape the hound, or of another writer that he has seen the blue heron chumming for fish. Even if you aver that you have seen a woodpecker running down the trunk of a tree as well as up, I shall be sure you have not seen correctly. It is the nuthatch and not the woodpecker that hops up and down and around the trees. It is easy to transcend any man’s experience; not so easy to transcend his reason. “Nobody has seen so many things as everybody,” yet a dozen men cannot see any farther than one, and the truth is not often a matter of majorities. If you tell me any incident in the life of bird or beast that implies the possession of what we mean by reason, I shall be very skeptical.

Am I guilty, then, as has been charged, of preferring the deductive method of reasoning to the more modern and more scientific inductive method? But I doubt if the inductive method would avail one in trying to prove that the old cow really jumped over the moon. We do deny certain things upon general principles, and affirm others. I do not believe that a rooster ever laid an egg, or that a male tiger ever gave milk. If your alleged fact contradicts fundamental principles, I shall beware of it; if it contradicts universal experience, I shall probe it thoroughly. A college professor wrote me that he had seen a crow blackbird catch a small fish and fly away with it in its beak. Now I have never seen anything of the kind, but I know of no principle upon which I should feel disposed to question the truth of such an assertion. I have myself seen a crow blackbird kill an English sparrow. Both proceedings I think are very unusual, but neither is antecedently improbable. If the professor had said that he saw the blackbird dive head first into the water for the fish, after the manner of the kingfisher, I should have been very skeptical. He only saw the bird rise up from the edge of the water with the wriggling fish in its mouth. It had doubtless seized it in shallow water near the shore. But I should discredit upon general principles the statement of the woman who related with much detail how she and her whole family had seen a pair “of small brown birds” carry their half-fledged young from their nest in a low bush, where there was danger from cats, to a new nest which they had just finished in the top of a near-by tree! Could any person who knows the birds credit such a tale? The bank-teller throws out the counterfeit coin or bill because his practiced eye and touch detect the fraud at once. On similar grounds the experienced observer rejects all such stories as the above. Darwin quotes an authority for the statement that our ruffed grouse makes its drumming sound by striking its wings together over its back. A recent writer says the sound is not made with the wings at all, but is made with the voice, just as a rooster crows. Every woodsman knows that neither statement is true, and he knows it, not on general principles, but from experience ­he has seen the grouse drum.

Birds that are not flycatchers sometimes take insects in the air; they do it clumsily, but they get the bug. On the other hand, flycatchers sometimes eat fruit. I have seen the kingbird carry off raspberries. All such facts are matters of observation. In the search for truth we employ both the deductive and the inductive methods; we deduce principles from facts, and we test alleged facts by principles.

The other day an intelligent woman told me this about a canary-bird: The bird had a nest with young in the corner of her cage; near by were some other birds in a cage ­I forget what they were; they had a full view of all the domestic affairs of the canary. This publicity she evidently did not like, for she tore out of the paper that covered the bottom of her cage a piece as large as one’s hand and wove it into the wires so as to make a screen against her inquisitive neighbors. My informant evidently believed this story. It was agreeable to her fancies and feelings. But see the difficulties in the way. How could the bird with its beak tear out a broad piece of paper? then, how could it weave it into the wires of its cage? Furthermore, the family of birds to which the canary belongs are not weavers; they build cup-shaped nests, and they have had no use for screens or covers, and they never have made them. Just what was the truth about the matter I cannot say, but if we know anything about animal psychology, we know that was not the truth. It is always risky to attribute to an animal any act its ancestors could not have performed.

Again, things are reported as facts that are not so much contrary to reason as contrary to all experience, and with these, too, I have my difficulties. A recent writer upon our wild life says he has discovered that the cowbird watches over its young and assists the foster-parents in providing food for them ­an observation so contrary to all that we know of parasitical birds, both at home and abroad, that no real observer can credit the statement. Our cowbird has been under observation for a hundred years or more; every dweller in the country must see one or more young cowbirds being fed by their foster-parents every season, yet no competent observer has ever reported any care of the young bird by its real parent. If this were true, it would make the cowbird only half parasitical ­an unheard-of phenomenon.

The same writer tells this incident about a grouse that had a nest near his cabin. One morning he heard a strange cry in the direction of the nest, and taking the path that led to it, he met the grouse running toward him with one wing pressed close to her side, and fighting off two robber crows with the other. Under the closed wing the grouse was carrying an egg, which she had managed to save from the ruin of her nest. The bird was coming to the hermit for succor. Now, am I skeptical about such a story, put down in apparent good faith in a book of natural history as a real occurrence, because I have never seen the like? No; I am skeptical because the incident is so contrary to all that we know about grouse and all other wild birds. Our belief in nearly all matters takes the line of least resistance, and it is easier for me to believe that the writer deceived himself, than that such a thing ever happened. In the first place, a grouse could not pick up an egg with her wing when crows were trying to rob her, and, in the second place, she would not think far enough to do it if she had the power. What was she going to do with the egg? Bring it to the hermit for his breakfast? This last supposition is just as reasonable as any part of the story. A grouse will not readily leave her unfledged young, but she will leave her eggs when disturbed by man or beast with apparent unconcern.

It is the rarest thing in the world that real observers see any of these startling and exceptional things in nature. Thoreau saw none. White saw none. Charles St. John saw none. John Muir reports none, Audubon none. It is always your untrained observer that has his poser, his shower of frogs or lizards, or his hoop snakes, and the like. The impossible things that country people see or hear of would make a book of wonders. In some places fishermen believe that the loon carries its egg under its wing till it hatches, and one would say that they are in a position to know. So they are. But opportunity is only half the problem; the verifying mind is the other half. One of our writers of popular nature books relates this curious incident of “animal surgery” among wild ducks. He discovered two eider ducks swimming about a fresh-water pond and acting queerly, “dipping their heads under water and keeping them there for a minute or more at a time.” He later discovered that the ducks had large mussels attached to their tongues, and that they were trying to get rid of them by drowning them. The birds had discovered that the salt-water mussel cannot live in fresh water. Now am I to accept this story without question because I find it printed in a book? In the first place, is it not most remarkable that if the ducks had discovered that the bivalves could not live in fresh water, they should not also have discovered that they could not live in the air? In fact, that they would die as soon in the air as in the fresh water? See how much trouble the ducks could have saved themselves by going and sitting quietly upon the beach, or putting their heads under their wings and going to sleep on the wave. Oysters are often laid down in fresh water to “fatten” before being sent to market, and probably mussels would thrive for a short time in fresh water equally well. In the second place, a duck’s tongue is a very short and stiff affair, and is fixed in the lower mandible as in a trough. Ducks do not protrude the tongue when they feed; they cannot protrude it; and if a duck can crush a mussel-shell with its beak, what better position could it have the bivalve in than fast to the tongue between the upper and the lower mandible? The story is certainly a very “fishy” one. In all such cases the mind follows the line of least resistance. If the ducks were deliberately holding their bills under water, it is easier to believe that they did it because they thereby found some relief from pain, than that they knew the bivalves would let go their hold sooner in fresh water than in salt or than in the air. A duck’s mouth held open and the tongue pinched by a shell-fish would doubtless soon be in a feverish and abnormal condition, which cool water would tend to alleviate. One is unable to see how the ducks could have acquired the kind of human experimental knowledge attributed to them. A person might learn such a secret, but surely not a duck. In discovering and in eluding its enemies, and in many other ways, the duck’s wits are very sharp, but to attribute to them a knowledge of the virtues of fresh water over salt in a certain unusual emergency ­an emergency that could not have occurred to the race of ducks, much less to individuals often enough for a special instinct to have been developed to meet it ­is to make them entirely human.

The whole idea of animal surgery which the incident implies ­such as mending broken legs with clay, salving wounds with pitch, or resorting to bandages or amputations ­is preposterous. Sick or wounded animals will often seek relief from pain by taking to the water or to the mud, or maybe to the snow, just as cows will seek the pond or the bushes to escape the heat and the flies, and that is about the extent of their surgery. The dog licks his wound; it no doubt soothes and relieves it. The cow licks her calf; she licks him into shape; it is her instinct to do so. That tongue of hers is a currycomb, plus warmth and moisture and flexibility. The cat always carries her kittens by the back of the neck; it is her best way to carry them, though I do not suppose this act is the result of experiment on her part.

A chimney swift has taken up her abode in my study chimney. At intervals, day or night, when she hears me in the room, she makes a sudden flapping and drumming sound with her wings to scare me away. It is a very pretty little trick and quite amusing. If you appear above the opening of the top of a chimney where a swift is sitting on her nest, she will try to drum you away in the same manner. I do not suppose there is any thought or calculation in her behavior, any more than there is in her nest-building, or any other of her instinctive doings. It is probably as much a reflex act as that of a bird when she turns her eggs, or feigns lameness or paralysis, to lure you away from her nest, or as the “playing possum” of a rose-bug or potato-bug when it is disturbed.

One of the writers referred to above relates with much detail this astonishing thing of the Canada lynx: He saw a pack of them trailing their game ­a hare ­through the winter woods, not only hunting in concert, but tracking their quarry. Now any candid and informed reader will balk at this story, for two reasons: (1) the cat tribe do not hunt by scent, but by sight, ­they stalk or waylay their game; (2) they hunt singly, they are all solitary in their habits, they are probably the most unsocial of the carnivora, ­they prowl, they listen, they bide their time. Wolves often hunt in packs. I have no evidence that foxes do, and if the cats ever do, it is a most extraordinary departure. A statement of such an exceptional occurrence should always put one on his guard. In the same story the lynx is represented as making curious antics in the air to excite the curiosity of a band of caribou, and thus lure one of them to its death at the teeth and claws of the waiting hidden pack. This also is so uncatlike a proceeding that no woodsman could ever credit it. Hunters on the plains sometimes “flag” deer and antelope, and I have seen even a loon drawn very near to a bather in the water who was waving a small red flag. But none of our wild creatures use lures, or decoys, or disguises. This would involve a process of reasoning quite beyond them.

Many instances have been recorded of animals seeking the protection of man when pursued by their deadly enemies. I heard of a rat which, when hunted by a weasel, rushed into a room where a man was sleeping, and took refuge in the bed at his feet. I heard Mr. Thompson Seton tell of a young pronghorn buck that was vanquished by a rival, and so hotly pursued by its antagonist that it sought shelter amid his horses and wagons. On another occasion Mr. Seton said a jack rabbit pursued by a weasel upon the snow sought safety under his sled. In all such cases, if the frightened animal really rushed to man for protection, that act would show a degree of reason. The animal must think, and weigh the pros and cons. But I am convinced that the truth about such cases is this: The greater fear drives out the lesser fear; the animal loses its head, and becomes oblivious to everything but the enemy that is pursuing it. The rat was so terrified at the demon of a weasel that it had but one impulse, and that was to hide somewhere. Doubtless had the bed been empty, it would have taken refuge there just the same. How could an animal know that a man will protect it on special occasions, when ordinarily it has exactly the opposite feeling? A deer hotly pursued by a hound might rush into the barn-yard or into the open door of the barn in sheer desperation of uncontrollable terror. Then we should say the creature knew the farmer would protect it, and every woman who read the incident, and half the men, would believe that that thought was in the deer’s mind. When the hunted deer rushes into the lake or pond, it does so, of course, with a view to escape its pursuers, and wherever it seeks refuge this is its sole purpose. I can easily fancy a bird pursued by a hawk darting into an open door or window, not with the thought that the inmates of the house will protect it, but in a panic of absolute terror. Its fear is then centred upon something behind it, not in front of it.

When an animal does something necessary to its self-preservation, or to the continuance of its species, it probably does not think about it as a person would, any more than the plant or tree thinks about the light when it bends toward it, or about the moisture when it sends down its tap-root. Touch the tail of a porcupine ever so lightly, and it springs up like a trap and your hand is stuck with quills. I do not suppose there is any more thinking about the act, or any more conscious exercise of will-power, than there is in a trap. An outward stimulus is applied and the reaction is quick. Does not man wink, and dodge, and sneeze, and laugh, and cry, and blush, and fall in love, and do many other things without thought or will? I do not suppose the birds think about migrating, as man does when he migrates; they simply obey an inborn impulse to move south or north, as the case may be. They do not think about the great lights upon the coast that blaze out with a fatal fascination in their midnight paths. If they had independent powers of thought, they would avoid them. But the lighthouse is comparatively a new thing in the life of birds, and instinct has not yet taught them to avoid it. To adapt means to an end is an act of intelligence, but that intelligence may be inborn and instinctive as in the animals, or it may be acquired and therefore rational as in man.

“Surely,” said a woman to me, “when a cat sits watching at a mouse-hole, she has some image in her mind of the mouse in its hole?” Not in any such sense as we have when we think of the same subject. The cat has either seen the mouse go into the hole, or else she smells him; she knows he is there through her senses, and she reacts to that impression. Her instinct prompts her to hunt and to catch mice; she doesn’t need to think about them as we do about the game we hunt; Nature has done that for her in the shape of an inborn impulse that is awakened by the sight or smell of mice. We have no ready way to describe her act as she sits intently by the hole but to say, “The cat thinks there is a mouse there,” while she is not thinking at all, but simply watching, prompted to it by her inborn instinct for mice.

The cow’s mouth will water at the sight of her food when she is hungry. Is she thinking about it? No more than you are when your mouth waters as your full dinner-plate is set down before you. Certain desires and appetites are aroused through sight and smell without any mental cognition. The sexual relations of the animals also illustrate this fact.

We know that the animals do not think in any proper sense as we do, or have concepts and ideas, because they have no language. To be sure, a deaf mute thinks without language because a human being has the intelligence which language implies, or which was begotten in his ancestors by its use through long ages. Not so with the lower animals. They are like very young children in this respect; they have impressions, perceptions, emotions, but not ideas. The child perceives things, discriminates things, knows its mother from a stranger, is angry, or glad, or afraid, long before it has any language or any proper concepts. Animals know only through their senses, and this “knowledge is restricted to things present in time and space.” Reflection, or a return upon themselves in thought, of this they are not capable. Their only language consists of various cries and calls, expressions of pain, alarm, joy, love, anger. They communicate with one another, and come to share one another’s mental or emotional states, through these cries and calls. A dog barks in various tones and keys, each of which expresses a different feeling in the dog. I can always tell when my dog is barking at a snake; there is something peculiar in the tone. The hunter knows when his hound has driven the fox to hole by a change in his baying. The lowing and bellowing of horned cattle are expressions of several different things. The crow has many caws, that no doubt convey various meanings. The cries of alarm and distress of the birds are understood by all the wild creatures that hear them; a feeling of alarm is conveyed to them ­an emotion, not an idea.

How could a crow tell his fellows of some future event, or of some experience of the day? How could he tell him this thing is dangerous, this is harmless, save by his actions in the presence of those things? Or how tell of a newly found food supply save by flying eagerly to it? A fox or a wolf could warn its fellow of the danger of poisoned meat by showing alarm in the presence of the meat. Such meat would no doubt have a peculiar odor to the keen scent of the fox or the wolf. Animals that live in communities, such as bees and beavers, cooperate with each other without language, because they form a sort of organic unity, and what one feels all the others feel. One spirit, one purpose, fills the community.

It is said on good authority that prairie-dogs will not permit weeds or tall grass to grow about their burrows, as these afford cover for coyotes and other enemies to stalk them. If they cannot remove these screens, they will leave the place. And yet they will sometimes allow a weed such as the Norse nettle or the Mexican poppy to grow on the mound at the mouth of the den where it will afford shade and not obstruct the view. At first thought this conduct may look like a matter of calculation and forethought, but it is doubtless the result of an instinct that has been developed in the tribe by the struggle for existence, and with any given rodent is quite independent of experience. It is an inherited fear of every weed or tuft of grass that might conceal an enemy.

I am told that prairie wolves will dig up and eat meat that has been poisoned and then buried, when they will not touch it if left on the surface. In such a case the ranchmen think the wolf has been outwitted; but the truth probably is that there was no calculation in the matter; the soil drew out or dulled the smell of the poison and of the man’s hand, and so allayed the wolf’s suspicions.

I suppose that when an animal practices deception, as when a bird feigns lameness or a broken wing to decoy you away from her nest or her young, it is quite unconscious of the act. It takes no thought about the matter. In trying to call a hen to his side, a rooster will often make believe he has food in his beak, when the pretended grain or insect may be only a pebble or a bit of stick. He picks it up and then drops it in sight of the hen, and calls her in his most persuasive manner. I do not suppose that in such cases the rooster is conscious of the fraud he is practicing. His instinct, under such circumstances, is to pick up food and call the attention of the hen to it, and when no food is present, he instinctively picks up a pebble or a stick. His main purpose is to get the hen near him, and not to feed her. When he is intent only on feeding her, he never offers her a stone instead of bread.

We have only to think of the animals as habitually in a condition analogous to, or identical with, the unthinking and involuntary character of much of our own lives. They are creatures of routine. They are wholly immersed in the unconscious, involuntary nature out of which we rise, and above which our higher lives go on.