The Woodpeckers Part 3

Besides his half-brothers, the narrow-fronted and ant-eating woodp.e.c.k.e.rs, the Carpenter has a numerous family of cousins,--the red-headed, the red-bellied, the golden-fronted, the Gila,[1] and the Lewis's woodp.e.c.k.e.rs. These all belong to one genus, and are much alike in structure, though totally different in color. Most of them are Western or Southwestern birds, but one is found in nearly all parts of the United States lying between the Hudson River and the Rocky Mountains, and is the most abundant woodp.e.c.k.e.r of the middle West. This well-known cousin is the red-headed woodp.e.c.k.e.r, the tricolored beauty that sits on fence-posts and telegraph poles, and sallies out, a blaze of white, steel-blue, and scarlet, a gorgeous spectacle, whenever an insect flits by. He is the one that raps so merrily on your tin roofs when he feels musical.

[Footnote 1: So named from being found along the Gila River.]

In many ways the red-head, as he is familiarly called, is like his carpenter cousin. Both indulge in long-continued drumming; both catch flies expertly on the wing; and both have the curious habit of laying up stores of food for future use. The Californian woodp.e.c.k.e.r not only stores acorns, but insect food as well. But though the Carpenter's habits have long been known, it is a comparatively short time since the red-head was first detected laying up winter supplies.

The first to report this habit of the red-head was a gentleman in South Dakota, who one spring noticed that they were eating _young_ gra.s.shoppers. At that season he supposed that all the insects of the year previous would be dead or torpid, and certainly full-grown, while those of the coming summer would be still in the egg. Where could the bird find half-grown gra.s.shoppers? Being interested to explain this, he watched the red-heads until he saw that one went frequently to a post, and appeared to get something out of a crevice in its side. In that post he found nearly a hundred gra.s.shoppers, still alive, but wedged in so tightly they could not escape. He also found other hiding-places all full of gra.s.shoppers, and discovered that the woodp.e.c.k.e.rs lived upon these stores nearly all winter.

But it is not gra.s.shoppers only that the red-head h.o.a.rds, though he is very fond of them. In some parts of the country it is easier to find nuts than to find gra.s.shoppers, and they are much less perishable food.

The red-head is very fond of both acorns and beechnuts. Probably he eats chestnuts also. Who knows how many kinds of nuts the red-head eats? You might easily determine not only what he will eat, but what he prefers, if a red-headed woodp.e.c.k.e.r lives near you. Lay out different kinds of nuts on different days, putting them on a shed roof, or in some place where squirrels and blue jays would not be likely to dare to steal them, and see whether he takes all the kinds you offer. Then lay out mixed nuts and notice which ones he carries off first. If he takes all of one kind before he takes any of the others, we may be sure that he has discovered his favorite nut. Such little experiments furnish just the information which scientific men are glad to get.

[Ill.u.s.tration]

It is well known that the red-head is very fond of beechnuts. Every other year we expect a full crop of nuts, and close observation shows that the red-heads come to the North in much larger numbers and stay much later on these years of plenty than on the years of scanty crops.

Lately it has been discovered that they not only eat beechnuts all the fall, but store them up for winter use. This time the observation was made in Indiana. There, when the nuts were abundant, the red-heads were seen busily carrying them off. Their acc.u.mulations were found in all sorts of places: cavities in old tree-trunks contained nuts by the handful; knot-holes, cracks, crevices, seams in the barns were filled full of nuts. Nuts were tucked into the cracks in fence-posts; they were driven into railroad ties; they were pounded in between the s.h.i.+ngles on the roofs; if a board was sprung out, the s.p.a.ce behind it was filled with nuts, and bark or wood was often brought to cover over the gathered store. No doubt children often found these hiding-places and ate the nuts, thinking they were robbing some squirrel's h.o.a.rd.

In the South, where the beech-tree is replaced by the oak, the red-heads eat acorns. I should like to know whether they store acorns as they do beechnuts. Are chestnuts ever laid up for winter? How far south is the habit kept up? Is it observed beyond the limits of a regular and considerable snowfall? That is, do the birds lay up their nuts in order to keep them out of the snow, or for some other reason?

It remains to be discovered if other woodp.e.c.k.e.rs have h.o.a.rding-places.

We know that the sapsucker eats beechnuts, and the downy and the hairy woodp.e.c.k.e.rs also; that the red-bellied woodp.e.c.k.e.r and the golden-winged flicker eat acorns; and I have seen the downy woodp.e.c.k.e.r eating chestnuts, or the grubs in them, hanging head downward at the very tip of the branches like a chickadee. It may be possible that some of these lay up winter stores.

[Ill.u.s.tration: Head of the Lewis's Woodp.e.c.k.e.r.]

It is known that the Lewis's woodp.e.c.k.e.r occasionally shows signs of a h.o.a.rding instinct. It was recently noted that in the San Bernardino Mountains of California the Lewis's woodp.e.c.k.e.r, after driving away the smaller Californian woodp.e.c.k.e.rs, tried to put acorns into the holes the Carpenter had made, but, being unused to the work, did it very clumsily.

Soon after this observation was published, a boy friend living near Denver told me that a short time before he had seen a woodp.e.c.k.e.r that had a large quant.i.ty of acorns sh.e.l.led and broken into quarters, on which he was feeding. This woodp.e.c.k.e.r was identified beyond a doubt as the Lewis's woodp.e.c.k.e.r. So we begin to suspect that the habit of storing up food is not an uncommon one among the woodp.e.c.k.e.rs.

X

A STUDY OF ACQUIRED HABITS

Something interesting yet remains to be discovered of the h.o.a.rding habit of the red-head. How strange that so familiar a bird should have a habit so easily detected, and yet that no one in all these years should speak of it! Who does not know how mice and chipmunks hide their food? Who has not watched the blue jay skulking off to hide an acorn where he will be sure to forget it? Who does not remember the articles his pet Jim Crow stole and lost to him forever? The h.o.a.rding habit has long been observed of many dull-colored, rare, or insignificant creatures. That one so noisy, gay-colored, tame, and abundant as our red-headed woodp.e.c.k.e.r should have the same habit and escape observation is certainly remarkable. But though it is over twenty years since the storing of gra.s.shoppers was recorded and twelve since the practice of laying up beechnuts was observed, very little seems to have been learned of the habit since these records were made.

There are two points to be considered: the habit long remained unknown; after it was discovered, it was long in being reaffirmed. It seems that, if it were a general habit, more would be known about it. Now if it is not a universal habit, it must be one of two alternatives, either a custom falling into disuse, or a new one just being acquired. That a habit so remarkable and so advantageous should be discarded after being universal is scarcely possible; that a habit so noticeable, if it were general, should remain unknown is improbable; that a habit which made life in winter both secure and easy should, if introduced by a few enterprising birds, become a universal custom, is not without a parallel. The probabilities point to the custom of h.o.a.rding food as a recently _acquired habit_.

Acquired habits are not rare among birds. The chimney swift has learned to nest in chimneys since the Pilgrims landed; for there were no chimneys before that time. There is the evidence of old writers to show that they acquired the habit within fifty years of the time of the first permanent settlements in New England. The eaves swallow learned to transfer its nest from the side of a cliff to the side of a barn in less time. Most birds will change their food as soon as a new dainty is procurable, and they will even invent methods of getting it, if it is much to their taste. The way the English sparrows have learned to tear open corn husks so as to eat the corn in the milk is a good example, for our maize does not grow in England, and they have had to learn about its good qualities in the few years since they have become established outside of the cities. Yet it is already a well-established habit. So quickly does a habit spread from one bird to another, until it becomes the rule instead of the exception! Acquired habits always show adaptability, and often much forethought and reason. It is the shrewd bird that learns new tricks.

Now there is not known among birds any evidence of greater forethought and reason than working hard in pleasant weather, when food is plentiful beyond all hope of ever exhausting it, to lay up provision for winter.

How does the woodp.e.c.k.e.r know that winter will come this year? That there was a winter last year and the year before does not make it certain, but only probable, that there will be one this year. We cannot know ourselves that the seasons will change until we learn enough of astronomy to understand the proof. Nor does instinct explain the habit, as some would declare: since not all red-heads have the habit, though all must have instinct. It would seem as if memory and reason had devised this plan for outwitting winter, the bird's old enemy.

The red-head is not a grub-eating woodp.e.c.k.e.r. Though beetles make up a third of his food, their larvae do not form any part of it. Half his food for the entire year is vegetable, and the animal portion is composed princ.i.p.ally of beetles, ants, caterpillars, and gra.s.shoppers, which in winter time are hidden in snug places, or are dead under the snow. There are few berries in winter. The few seedy, weedy plants that stick up above the snow give to the birds the little they have; but the red-head's vegetable fare is limited at that season and his animal food almost lacking. Winter in the North is all very well for the hairy and downy cousins that like to hammer frozen tree-trunks for frozen grubs; but our red-headed friend does not eat grubs by preference. Rather than change his habits he will change his boarding-place. So he is a migratory woodp.e.c.k.e.r, though the woodp.e.c.k.e.rs are naturally home-loving birds, and do not migrate from preference. If, however, he can lay up a store of vegetable or animal food, he can winter in any climate.

h.o.a.rding is thus an invention as important to the woodp.e.c.k.e.r world as electric cars and telephones are to men. The probabilities are that this is a recent improvement in the red-head's ways of living.

Another set of facts increases the probabilities of our supposition. It is a very delicate subject to handle because it affects the reputation of a family in good standing; but there is positive proof that sometimes the red-head has been guilty of crimes which would give a man a full column in the newspapers with staring headlines. If such deeds were not a thousand times less common among woodp.e.c.k.e.rs than they are among men the red-head would be declared an outlaw. He has been proved to be a hen-roost robber, a murderer, and a cannibal. In Florida he has sucked hen's eggs. In Iowa he has been seen to kill a duckling. There is a record in Ohio that he pecked holes in the walls of the eaves swallow's nest and stole all the eggs, and that he was finally killed in the act of robbing a setting hen's nest. Within the s.p.a.ce of fifteen years, from Montana, Georgia, Colorado, New York, and Ontario, in addition to the records mentioned already from Florida, Ohio, and Iowa, come accounts of his stealing birds' eggs and murdering and eating other birds. The evidence is indisputable.

It is charity to suppose that this is the work of natural criminals, or of degenerate, under-witted, or demented woodp.e.c.k.e.rs. Why should there not be such individuals among birds? One point is certain: so notable a habit could not long escape detection, since it is a barnyard crime. He who robs hen's nests gets caught--if he is a bird. Either these occurrences are very rare, not seen because of their extreme rarity, or they indicate a new custom just coming in. And the same is true of the habit of h.o.a.rding food; it is rare, or it is new.

The frequency of such occurrences can be determined only by observation; but the time of their origin might be approximated in another way. If we could fix the date when the bird could not have done what he is now doing for simple lack of opportunity, we might say that the habit has been acquired since a certain date--as we have said of the English sparrow eating maize, of the chimney swift nesting in chimneys, and the cliff swallow building under the eaves. But we have no such help on the case of the red-head, which never has been without opportunities to get birds' eggs and to kill other birds.

But there is a parallel case in another species where the date of an acquired habit can be proved. In Florida the red-bellied woodp.e.c.k.e.r has earned the names Orange Borer and Orange Sapsucker because he eats oranges. It is true that he is not charged with doing damage, because he attacks only the over-ripe and unmarketable fruit; it is known that the habit is not general yet, for even where the birds are abundant only a single bird or a pair will be found eating oranges, and always the same pair, proving that it is a habit not yet learned by all of the species; close observers declare, too, that it is but a few years since the bird took up the habit; and, finally, we know that this must be the case, for, though the wild orange was introduced by the Spaniards, the sweet fruit was not extensively cultivated until recently. Here is a habit which undoubtedly has been acquired within twenty years or so, which will in all probability increase until instead of being the exception it is the rule.

Why may not the red-head's occasional cannibalism, unless this is mere individual degeneracy, and his more common custom of h.o.a.rding be habits that he is acquiring? Why, indeed, may not the Californian woodp.e.c.k.e.r's distinguis.h.i.+ng trait be a habit which began like these among a few birds here and there, wiser or more progressive than the rest, and which in time became general and established? Why may not the two observed instances of the Lewis's woodp.e.c.k.e.r be examples of a similar habit just beginning? The very differences in their methods point to that explanation. The Lewis's woodp.e.c.k.e.r that had seen the Carpenter's work tried to imitate him; the one that lived outside his range adopted a way of his own, unnoticed before among woodp.e.c.k.e.rs, and sh.e.l.led and quartered his nuts before he stored them.

It is remarkable that these four woodp.e.c.k.e.rs are cousins; they belong to the same genus, and they have essentially the same structure, tastes, and habits. Why should it be strange if their minds were alike too? if they had a natural bent toward acc.u.mulativeness, and a natural desire to try new wrinkles? We are sure that one of them has acquired a new habit within a few years. Why may we not suppose as a basis and a spur to further investigation that the others also are acquiring ways new and strange?

XI

THE WOODp.e.c.k.e.r'S TOOLS: HIS BILL

There is an old saying, "You may know a carpenter by his chips;" but, though chips are seldom long absent when a woodp.e.c.k.e.r is about, can we call the woodp.e.c.k.e.r a carpenter? Is he not both in his works and ways of working--with the one exception of the Californian woodp.e.c.k.e.r--more of a miner?

For the carpenter takes pieces of wood, bit by bit, and joins them together till at last he has built a lofty skeleton or framework for his dwelling, which last of all he covers over and closes in; and the tools he uses are saw and hammer. With these alone he could build his house, though it might be neither very large nor very good. When a carpenter's house is finished, it is neither a cave nor a hole, but a pavilion built in the open air after the model of a spreading tree,--which frames a roof with its branches and s.h.i.+ngles it with overlapping leaves. There is nothing in the woodp.e.c.k.e.r's way of building which corresponds to that.

Quite different are the miner's methods. In the West, where the barren mountain sides stretch up into snowclad summits, on the face of slopes as seamed and gray and verdureless as the wrinkled trunk of an aged oak, I have seen holes where human woodp.e.c.k.e.rs burrow. The entrance to a mine half-way up a hillside looks strikingly like a woodp.e.c.k.e.r's hole and scarcely larger. Nor does the likeness vanish as we think how in their long tunnels inside their mountains of gold and iron and silver the delving miners are picking and prying and picking to lengthen their burrows just as the woodp.e.c.k.e.rs peck and pry and peck inside their wooden mountain, the tree-trunk. Which shall we call the woodp.e.c.k.e.r--a carpenter or a miner?

What are the miner's tools? Pick and drill, are they not? What are the woodp.e.c.k.e.r's? The same. Certainly we shall see, if we stop to think, that it is not a chisel that he uses, as we sometimes say. A chisel is a knife driven by blows of a hammer; like a knife its effectiveness depends upon the sharpness and length of its cutting edge. But a woodp.e.c.k.e.r's bill is not a cutting tool. It is a wedge, but a wedge working on a different principle from a knife-edge. Look at this one and observe that, though strong and stout, it is not sharp and has no true cutting edge. It is a tapering, square-ended, flat-sided tool, rather six-sided at the base and holding its bevel and angles to the tip. The woodp.e.c.k.e.r's bill is a pick, not a chisel. It is used like a pick, being driven home with a heavy blow and getting its efficiency from its own weight and wedge-shape and from the force with which it is impelled.

Watch the downy woodp.e.c.k.e.r at his work and see what st.u.r.dy blows he delivers, pausing after each one to aim and drive home another telling stroke. This is pick-axe work. But sometimes he rattles off a succession of taps so short and quick that they blend together in one continuous drumming, too light and quick to be likened to the ponderous swing of the pick-axe. Now he is drilling. The work of a drill is to cut out a small deep hole either by twirling (as in drilling metals) or by tapping (as in drilling stone). The woodp.e.c.k.e.r drills by the latter method and there is a curious likeness between his bill and the mason's tools.

[Ill.u.s.tration: Head of Ivory-billed Woodp.e.c.k.e.r.]

Any one who has lived in a granite country knows the deep round holes that stone masons make when they split rock. Did you ever wonder why they are as large at the bottom as at the top? If you remember the shape of a mason's drill, you will recollect that it looks a little like a stick of home-made mola.s.ses candy bitten off when it was just soft enough to stretch a little. The mason's drill is a round iron rod with a thin, flat end, sharpened on the edge and a little pointed in the centre. In the flattening of the sides and the width across the tip its end resembles that of a typical woodp.e.c.k.e.r's bill. The woodp.e.c.k.e.rs that drill for grubs, especially the largest, the logc.o.c.k and the ivory-billed woodp.e.c.k.e.r, have the tip remarkably flattened. The likeness to the drill does not go farther because the woodp.e.c.k.e.r's bill is a combination tool; but it is drill-pointed rather than pick-pointed.

What is the advantage of this compressed tip? Can the bird pick as well as he could with a sharp point? The bird and the mason reap the same benefit from this form of tool. A sharp-pointed drill would bind in the hole and could neither be driven ahead nor removed without difficulty, but the sharp-edged tool cuts a hole as wide as the instrument. There is, of course, some difference between working in stone and in wood, but the principle is the same. The mason strikes his drill with his hammer and cuts a crease in the stone; then lifts and turns the drill, cutting a crease in another direction; and so by continually changing the direction of the cuts until they radiate from a centre like the spokes of a wheel, he finally reduces a little circle of stone to a powder fine enough to be blown out of the hole. In drilling for a grub the woodp.e.c.k.e.r must do much the same thing. He wishes to keep his hole small at the top so as to save work, yet it must be large enough at the bottom to admit the borer when nipped between his mandibles; therefore he needs an instrument that, like a drill or a chisel, will cut a straight-sided hole. Indeed, we might call it a chisel just as well if it were not a double-wedge instead of a single wedge and if it did not move when it is struck instead of being held stationary beneath the blows.

When he is digging his house the woodp.e.c.k.e.r uses his bill as a pick-axe.

When he is digging for grubs he uses it as a drill. Now some species drill very little and some a great deal, according to the number of grubs they feed on; but all dig holes to nest in,--that is, all use their bills as picks but only a few employ them as drills. The flickers, for example, seldom drill for grubs, their food being picked up on the surface or dug from the earth; yet they excavate the deepest, roomiest holes made by any woodp.e.c.k.e.rs of their size; they use their bills effectively as pick-axes, but seldom, very seldom, as drills. And what do we find? No drill-point--not a truncate, compressed bill fit for drilling, but a sharper, pointed, rounded, _curving_ bill. Notice the ordinary pick-axe and see how much nearer the flicker's bill than the logc.o.c.k's or the ivory-billed woodp.e.c.k.e.r's it is. Why is a flicker's bill better for being curved also? Why do the drilling woodp.e.c.k.e.rs have a perfectly straight bill? We should find by studying the birds and their food that there is a direct relation between the shape of the bill and the amount of drilling a woodp.e.c.k.e.r does; that the grub-eating or drilling woodp.e.c.k.e.rs have a straight bill, for working in small deep holes, while the flickers have a curved bill for prying out chips. And we should note that the flicker's bill is most like the ordinary bill of perching birds, while the drilling bill, as typified by the logc.o.c.k's and the hairy woodp.e.c.k.e.r's bills, is a more specialized tool, limited to fewer uses, but more effective within its limits.

There is another detail of the woodp.e.c.k.e.r's bills which casts light upon their habits. The species that drill most have their nostrils closely covered by little tufts of stiff feathers, scarcely more than bristles, which turn forward over the nostril. The density and the length of these tufts agree very well with the kind of work the woodp.e.c.k.e.r does; for in the hairy and the downy, which are continually drilling and raising a dust in rotten wood, they are very thick and noticeable, while in the red-head and the sapsucker they show as scarcely more than a few loose bristles, and in the flicker they barely cover the nostril. This seems a plain provision to keep the dust out of the bird's lungs; and we might cite as additional evidence the fact that the only other birds of similar tree-pecking habits, the nuthatches and the chickadees, have their nostrils protected in the same way. But we must always be cautious before drawing inferences of this sort to see what may be said on the other side. When we recollect that the crows and ravens and many kinds of finches, among other birds, none of which dig in the bark of trees or raise a dust, have their nostrils as completely covered, we see that we have perhaps discovered a _use_ for these nasal tufts but not the _cause_ of their being there. We must be careful not to mistake cause and accompaniment in our endeavor to explain differences in structure.

Let us see what we have learned and how to interpret it:--

That the woodp.e.c.k.e.r's bill is a combination of drill and pick-axe.

That the shape varies with the use to which it is most commonly put.

That the use varies with the food princ.i.p.ally eaten; or, what is a step farther back, that the different kinds of food must be sought in different places and by different methods, and therefore require different tools.

Therefore the shape of the woodp.e.c.k.e.r's bill has a direct relation to the kind of food he eats. Please notice that we do not a.s.sert that it _causes_ him to eat a certain kind of food nor that a certain diet may not have affected the shape of the bill, causing it to be what we now see. Both may be at least partially true, but to prove either or both would need profound study, and all that we have observed is that the shape of the woodp.e.c.k.e.r's bill is _adapted_ to his food and that it varies with the kind of food he eats, or, to be more exact, with his ways of procuring it.