Every creature born into the natural world brings with him, I think, two ingrained or hereditary impulses for his salvation in moments of danger. One, for use when he is young and helpless, is to crouch motionless at the appearance of the enemy (opposite). The other, which appears later and explains why with rare exceptions any so-called savage beast is not to be feared unless wounded or cornered, is to take to his heels at the first warning that danger is loose in the neighborhood.
To the first impulse, here called "the saving instinct," birds and beasts of prey are possible but improbable exceptions. It may be that fox cubs, for example, which spend their early days in a den beyond human sight, do not hold still when alarmed, but it is significant that you never hear them, not a stir or a whimper, if you lay an ear down to the mouth of their den, though their keen ears or noses tell them of an enemy at hand. Later, when they are grown large enough to play in the sunshine, I have repeatedly observed that at any alarming noise—a sharp whistle on my part, or the bark of a dog in the distance—they invariably freeze in their tracks. After a quiet moment or two, long enough to make up what they would call their minds, they either resume their play or else slip quickly into the den, to be seen no more until the vixen returns and calls them out.
As for birds of prey, if ever you have watched young hawks or owls from your perch in a neighboring tree you may have noticed how still they commonly are, and how at any unnatural commotion they flatten down in the nest to become a part of the lifeless structure. Climb the nest tree now, slowly, carefully, with plentiful halts to quiet any feeling of alarm, and the moment your hat appears in sight the nestlings lift themselves up and open their mouths for food, evidently mistaking your hat or your shadow for the returning mother bird. Not till they recognize you as an enemy, too late, will they bristle their pinfeathers and hiss fiercely to scare you.
Of other young birds and animals, called the hunted in distinction from the hunting kind, one might say with Isaiah, a very observant prophet, "Their strength is to sit still." Three wholly natural reasons for their strength or salvation in time of danger are as follows:
First of all, the youngling that holds motionless close to earth cannot be seen, or at least he is seldom noticed by wild eyes. But be not misled here by any theories of "protective coloration," wherewith many naturalists please and deceive themselves. It is doubtless true, concerning the lower orders of animate life, that their pigment cells have a strange affinity, let us call it, for the coloration of their immediate environment. Thus, a flounder will quickly change the color of his back to match the color of the bottom on which he rests, as many insects harmonize their hues with that of the leaf or twig which supports them. By careful experimentation, Sir Edward Bagnell Poulton, Fellow of the Royal Society and professor of zoology at Oxford, apparently proved that the chromatophores (pigment cells) in the skin of a fish respond to any prolonged color impression received by the visual cells of the retina, with the result that his skin turns gray when his eyes see gray continuously, or turns brown when his eyes see brown. It has also been proved that the skin of a blinded fish invariably turns blackish, and black is not a color but the absence of all colors. What causes this mysterious color "affinity" between the body of a fish and his environment, or to what end, is still a matter of speculation on our part. Nature lets us see the change but refuses to reveal why she makes it.
Among the higher orders, whose color-pigment cells are less active and much less changeable, the simple fact is that a fawn with bright orange coat sprinkled with spots of glaring white has the same "invisibility" as a mottled brown grouse in the same place, so long as fawn or grouse holds quiet, but not a moment longer. Whatever the coloration, any bird or animal betrays himself by the first motion.
Next, from the hunting viewpoint, every bird or beast of prey associates life with motion so habitually, so completely, that a resting grouse or rabbit, or even a man, is in his eye only a part of the restful earth. To quote but a single example, I was sitting under a tree on the lake shore, watching a female sheldrake or scurry duck which had probably hidden her newly hatched brood and was now expertly catching minnows for them. Suddenly a hawk swooped with a paralyzing whirr of stiffened pinions. The sheldrake escaped by a flashing dive, losing only a few feathers, and the hawk wheeled in to perch on a branch so near my face that I dared not even wink. When his head was turned to look for his vanished prey I reached out a hand to grab his legs and bring him with threshing wings into my lap.
All theories to the contrary notwithstanding, I maintain that this wary hawk was deceived not by any protective coloration on my part but only by my quietude. And what did he think or feel, I wonder, when on being tossed free into the air he hovered a moment to glare down at me with fierce eyes before winging away to safety.
Finally, any wild bird or animal, excepting only a gorged beast of prey, gives off so very little scent when at rest that the keenest nose may pass without receiving a telltale message. This has been many times proved to my own satisfaction, at least, by having wild animals draw near without showing any sign of alarm at the dreaded man scent, paying me no attention until their eyes caught a purposeful motion, when commonly they came nearer instead of running away.
The same surprising thing was proved to anybody's satisfaction, I should think, by my setter Rab, whom I had trained to obey every word or whistle or hand signal before taking him to my summer camp. At home he honored his training by giving no heed to anything but game birds. In the wilderness, where he was occasionally permitted to range on either side while I followed an old logging road or fished a trout stream, he found a new world to his liking, and made the most of it by pointing everything he found as staunchly as ever he pointed grouse or woodcock in the home covers. On one occasion it might be only a deermouse; on another, a rarely seen fisher or "black cat"; on a third, when I approached his point, I heard the terrifying urumphumph of a startled bear.