The Woodpeckers Part 2

That he was not after grubs.

That he got, and undoubtedly ate, the soft inner bark of the tree.

That he got, and may have drunk, the sap.

We could not infer any more from a single instance, but the naturalists a.s.sure us that the bird is in the habit of injuring trees, that he never eats grubs intentionally, and that he eats too much bark for it to be regarded as taken accidentally with other food. About the sap they cannot be so sure, as it digests very quickly. There remain two points to prove: whether the sapsucker drills his holes for the sake of the sap, or for insects attracted by the sap, provided that he eats anything but the inner bark.

Our little specimen can tell us no more, but two mountain ash trees which were intimate acquaintances of mine from childhood can go on with the story. Do not be surprised that I speak of them as friends; the naturalist who does not make _friends_ of the creatures and plants about will hear few stories from them. These trees would not tell this tale to any one but an intimate acquaintance. Let us hear what they have to say about the sapsucker.

There are in the garden of my old home two mountain ash trees, thirty-six years of age, each having grown from a sprout that sprang up beside an older tree cut down in 1863. They stand not more than two rods apart; have the same soil, the same amount of sun and rain, the same exposure to wind, and equal care. During all the years of my childhood one was a perfectly healthy tree, full of fruit in its season, while the other bore only scanty crops, and was always troubled with cracked and scaling bark. To-day the unhealthy tree is more vigorous than ever before, while its formerly stalwart brother stands a mere wreck of its former life and beauty. What should be the cause of such a remarkable change when all conditions of growth have remained the same?

I admit that there is some internal difference in the trees, for all the birds tell me of it. One has always borne larger and more abundant fruit than the other, but this is no reason why the birds should strip all the berries from that tree before eating any from the other. When we know that the favorite tree stands directly in front of the windows of a much-used room and overhangs a frequented garden path, the preference becomes more marked. But robins, grosbeaks, purple finches, and the whole berry-eating tribe agree to choose one and neglect the other, and even the spring migrants will leave the gay red ta.s.sels of fruit still swinging on one tree, to scratch over the leaves and eat the fallen berries that lie beneath the other. My own taste is not keen in choosing between bitter berries, but the birds all agree that there is a decided difference in these trees,--did agree, I should say, for their favorite is the tree that is dying. Evidently this is a question of taste. It is interesting to observe that the sapsucker, which was never seen to touch the fruit of the trees, agrees with the fruit-eating birds. Nearly all his punctures were in the tree now dying. Is there a difference in the taste of the sap? Does the taste of the sap affect the taste of the fruit? Or is it merely a question of quant.i.ty? If he comes for sap, he prefers one tree to the other on the score either of better quality or greater quant.i.ty.

We will discuss later whether it is sap that he wishes: all that now concerns us is to note that the internal difference, whatever it is, is in favor of the tree that is dying; while the only external difference appears to be the marks left by the sapsucker. While one tree is sparingly marked by him, the other is tattooed with his punctures, placed in single rings and in belts around trunk and branches beneath every fork. It is a law of reasoning that, when every condition but one is the same and the effects are different, the one exceptional condition is the _cause_ of the difference. If these trees are alike in everything except the work of the sapsucker (the only internal difference apparently _offsetting_ his work in part), what inference do we draw as to the effect of his work?

We presume that he is killing the tree, without as yet knowing how he does it. What is his object? Good observers have stated that he draws a little sap in order to attract flies and wasps; that the sap is not drawn for its own sake, but as a bait for insects. Is this theory true?

The first objection is that it is improbable. The sapsucker is a retiring, woodland bird that would hesitate to come into a town garden a mile away from the nearest woods unless to get something he could not find in the woods. Had he wanted insects, he would have tapped a tree in the woods, or else he would have caught them in his usual flycatching fas.h.i.+on. There must have been something about the mountain ash tree that he craved. As it is a very rare tree in the vicinity of my home, the sapsucker's only chance to satisfy his longing was by coming to some town garden like our own.

Not only is the theory improbable, but it fails to explain the sapsucker's actions in this instance. In twenty years he was never seen to catch an insect that was attracted by the sap he drew. This does not deny that he may have caught insects now and then, but it does deny that he set the sap running for a lure. As he was never far away, and was sometimes only four and a half feet by measure from a chamber window, all that he did could be seen. He did not catch insects at his holes. He drank sap and ate bark.

Finally, the theory is not only improbable and inadequate, but in this instance it is impossible. I do not remember seeing a sapsucker in the tree in the spring; if he came in the summer, it must have been at rare intervals; but he was always there in the fall, when the leaves were dropping. At that season the insect hordes had been dispersed by the autumnal frosts, so that we know he did not come for insects.

In the many years during which I watched the sapsuckers--for there were undoubtedly a number of different birds that came, although never more than one at a time--there was such a curious similarity in their actions that it is entirely proper to speak as if the same bird returned year after year. His visits, as I have said, were usually made at the same season. He would come silently and early, with the evident intention of making this an all-day excursion. By eight o'clock he would be seen clinging to a branch and curiously observant of the dining-room window, which at that hour probably excited both his interest and his alarm.

Early in the day he showed considerable activity, flitting from limb to limb and sinking a few holes, three or four in a row, usually _above_ the previous upper girdle of the limbs he selected to work upon. After he had tapped several limbs he would sit waiting patiently for the sap to flow, lapping it up quickly when the drop was large enough. At first he would be nervous, taking alarm at noises and wheeling away on his broad wings till his fright was over, when he would steal quietly back to his sap-holes. When not alarmed, his only movement was from one row of holes to another, and he tended them with considerable regularity. As the day wore on he became less excitable, and clung cloddishly to his tree-trunk with ever increasing torpidity, until finally he hung motionless as if intoxicated, tippling in sap, a disheveled, s.m.u.tty, silent bird, stupefied with drink, with none of that brilliancy of plumage and light-hearted gayety which made him the noisiest and most conspicuous bird of our April woods.

Our mountain ash trees have told us several facts about the sapsucker:--

That he did not come to eat insects.

That he did come to drink sap, and that he probably ate the inner bark also.

That he drank the sap because he liked it, not for some secondary object, as insects.

That he could detect difference in the quality or quant.i.ty of the sap, which caused him to prefer a particular tree.

That this difference apparently was in the taste of the sap, and that the effects of a day's drinking of mountain ash sap seemed to indicate some intoxicant or narcotic quality in the sap of that particular tree.

That the effect of his work upon the tree was apparently injurious, as it is the only cause a.s.signed of a healthy tree's dying before a less healthy one of the same age and species, subject all its life to the same conditions.

So much we have learned about this sapsucker's habits, and now we should like to know why his work is harmful, and why that of the other woodp.e.c.k.e.rs is not. It is not because he drinks the sap. All the sap he could eat or waste would not harm the tree, if allowed to run out of a few holes. Think how many gallons the sugar-makers drain out of a single tree without killing the tree. But the sugar-maker takes the sap in the spring, when the crude sap is mounting up in the tree, while the sapsucker does not begin his work till midsummer or autumn, when the tree is sending down its elaborated sap to feed the trunk and make it grow. This accounts for the woodp.e.c.k.e.r's digging his pits _above_ the lines of the holes already in the tree. The loss of this elaborated sap is a greater injury than the waste of a far larger quant.i.ty of crude sap, so that on the season of the year when the sapsucker digs his holes depends in large measure the amount of damage he does. The injury that he does to the wood itself is trivial. He is not a wood_p.e.c.k.e.r_ except at time of nesting, and most woodp.e.c.k.e.rs prefer to build in a dead or dying branch, where their work does no hurt. But we know very well that a tree may be a wreck, riven from top to bottom by lightning, split open to the heart by the tempest, entirely hollow the whole length of its trunk, and yet may flourish and bear fruit. The tree lives in its outer layers. It may be crippled in almost any way, if the bark is left uninjured; but if an inch of bark is cut out entirely around the tree, it will die, for the sap can no longer run up and down to nourish it.

This is the sapsucker's crime: he girdles the tree,--not at his first coming, nor yet at his second, not with one row of holes, nor yet with two; but finally, after years perhaps, when row after row of punctures, each checking a little the flow of sap, have overlapped and offset each other and narrowed the channels through which it could mount and descend, until the flow is stopped. Then the tree dies. It is not the holes he makes, nor the sap he draws, but the way he places his holes that makes the sapsucker an unwelcome visitor. For an unacceptable individual he is to the farmer,--_persona non grata_, as kings say of amba.s.sadors who do not please their majesties. What shall we do with him, the only black sheep in all the woodp.e.c.k.e.r flock? Let him alone, unless we are positively sure that we know him from every other kind of woodp.e.c.k.e.r. The damage he does is trifling compared with what we should do if we made war upon other woodp.e.c.k.e.rs for some supposed wrong-doing of the sapsucker.

VIII

EL CARPINTERO

In California and along the southwestern boundary of the United States lives a woodp.e.c.k.e.r known among the Mexicans as El Carpintero, the Carpenter.

Carpentering is both his profession and his pastime, and he seems really to enjoy the work. When there is nothing more pressing to be done, he spends his time tinkering around, fitting acorns into holes in such great numbers and in so workmanlike a fas.h.i.+on that we do not know which is more remarkable, his patience or his skill. Every acorn is fitted into a separate hole made purposely for it, every one is placed b.u.t.t end out and is driven in flush with the surface, so that a much frequented tree often appears as if studded with ornamental nails. "What an industrious bird!" we exclaim; but still it takes some time to appreciate how enormous is the labor of the Carpenter. Whole trees will sometimes be covered with his work, until a single tree has thousands of acorns bedded into its bark so neatly and tightly that no other creature can remove them.

[Ill.u.s.tration: Work of Californian Woodp.e.c.k.e.r.]

We may take for examination, from specimens of the Carpenter's work, a piece of spruce bark seven inches long by six wide, containing ten acorns and two empty holes. As spruce bark is so much harder and rougher than the pine bark in which he usually stores his nuts,[1] this specimen looks rough and unfinished, and even shows some acorns driven in sidewise; but for another reason I have preferred it to better-looking examples of his work for study. As we shall see later, it gives us a definite bit of information about the bird.

[Footnote 1: They often use white-oak bark, fence-posts, telegraph poles, even the stalks of century-plants, when trees are not convenient.

(Merriam, _Auk_, viii. 117.)]

Think of the work of digging these twelve holes. Think of the labor of carrying these ten large acorns and driving them in so tightly that after years of shrinking they cannot be removed by a knife without injuring either the acorn or the bark. Yet how small a part of the woodp.e.c.k.e.r's year's work is here! How long could he live on ten acorns?

How many must he gather for his winter's needs? How many must he lose by forgetting to come back to them? We cannot calculate the work a single bird does nor the nuts he eats, for several birds usually work in company and may use the same tree; but all the woodp.e.c.k.e.rs are large eaters, and the Californian has been singled out for special mention.

Can we estimate the amount of work required to lay up one day's food?

Judging by the amount of nuts some other birds will eat, I should think that all ten acorns contained in this piece of bark could be eaten in one day without surfeit. The estimate seems to me well inside of his probable appet.i.te. I have experimented on this piece of bark, using a woodp.e.c.k.e.r's bill for a tool, and it takes me twenty minutes to dig a hole as large but not as neat as these. Doubtless it would not take the woodp.e.c.k.e.r as long; but at my rate of working, four hours were spent in digging these twelve holes. Then each acorn had to be hunted up and brought to the hole prepared for it. This entailed a journey, it may have been only from one tree to another, or it may have been, and very likely was, a considerable flight. For these acorns grew on oak-trees, and we find them driven into the bark of pines and spruces.

[Ill.u.s.tration]

This it is which gives our specimen its particular interest. While oaks and pines may be intermingled, though they naturally prefer different soils and situations, and in the Rocky Mountains the pine-belt lies above the oak region, spruce and oak trees do not grow in the same soil.

The spruce-belt stands higher up than the pine. As these nuts are stored in the bark of a spruce-tree, we have clear evidence that the bird must have carried them some distance. For every nut he made the whole journey back and forth, since he could carry but one at a time,--ten long trips back and forth, certainly consuming several minutes each.

Then each acorn had to be fitted to its hole. We have already spoken of the accuracy with which this is done, so that the Carpenter's work is a standing taunt to the hungry jays and squirrels which would gladly eat his nuts if they could get them. A careful observer tells us that when the hole is too small, the woodp.e.c.k.e.r takes the acorn out and makes the hole a little larger, working so cautiously, however, that he sometimes makes several trials before the acorn can be fitted and driven in flush with the bark. Some of these acorns show cracks down the sides, as if they had been split either in forcibly pulling them out of a hole not deep enough for them, or in driving them when green and soft into a hole too small for them. Of course after each trial the acorn must be hunted up where it lies on the ground and driven in again, and this takes considerable time.

As nearly as we can estimate it, not less than half a day must have been spent in putting these acorns where we find them. With smaller acorns, stored in pine bark, less time would have been required; but weeks, if not months, of work are spent in laying up the winter's stores.

How the woodp.e.c.k.e.r's back and jaws must have ached! Surely he is human enough to get tired with his work, and it is not play to do what this bird has done. Some of the acorns measure seven tenths of an inch in diameter by nine tenths in length, and the bird that carried them is smaller than a robin. How he must have hurried to reach his tree when the acorn was extra large! Yet he took time to drive every one in point foremost. Even those that lie upon their sides must have been forced into position by tapping the b.u.t.t. He knows very well which end of an acorn is which, does our Carpenter.

But what is the use of all this work? Why, if he wants acorns, does he not eat them as they lie scattered under the oaks, instead of taking pains to carry them away and put them into holes for the fun of eating them out of the holes afterward? The absurdity of this has led some people to surmise that the Carpenter chooses none but weevilly acorns, and stores them that the grub inside may grow large and fat and delicious. This would be very interesting, if it were true. There must of course be more weevilly acorns on the ground than he picks up, so that he could get as many grubs without taking all this trouble, and there is no reason why they should not be as large and good as those hatched out in holes in trees. When I wish to keep nuts sweet, I spread them out on the attic floor in the sun and air, keeping them where they will not touch each other. The Carpenter does practically the same thing. Is it probable that he tries to raise a fine crop of grubs in this way? If so, one or the other of us is doing just the wrong thing.

But if weevils are what the Carpenter wants, then the nuts in the bark should be wormy; yet only two of them show any sign of a weevil, and of these one appears from its dull color and weather-beaten look to be a nut deposited several years before the others by some other woodp.e.c.k.e.r.

Every other acorn is as hard, s.h.i.+ning, and bright colored as when it fell from the tree. Evidently the bird picked these nuts up while they were fresh and good; perhaps he chose them _because_ they were good and fresh. The possibility becomes almost a certainty when we observe that naturalists agree that the Carpenter uses no acorns but the sweet-tasting species. Now there are likely to be as many grubs in one kind of an acorn as in another, and he would scarcely refuse any kind that contained them, if grubs were what he wanted. The fact that he takes sweet acorns, and those only, shows that it is the meat of the nut that he wants. And all good naturalists agree that it is the kernel itself that he eats.

Why he stores them is not hard to decide when we remember that the Californian woodp.e.c.k.e.r, over a large part of his range, is a mountain bird. Though we think of California as the land of suns.h.i.+ne, it is not universal summer there. The mountain ranges have a winter as severe as that of New England, with a heavy snowfall. When the snow lies several feet deep among the pines and spruces of the uplands, the Carpenter is not distressed for food: his pantry is always above the level of the snow; he need neither scratch a meagre living from the edges of the snow-banks, nor go fasting. His fall's work has provided him not only with the necessities, but with the luxuries of life.

But why does he spend so much time in making holes? He might tuck his nuts into some natural crevice in the oak bark, or drop them into cavities which all birds know so well where to find. And leave them where any pilfering jay would be able to pick them out at his ease? Or put them in the track of every wandering squirrel? Jays and squirrels are never too honest to refuse to steal, but they find it harder to get the woodp.e.c.k.e.r's stores out of his pine-tree pantry than to pick up honest acorns of their own. So, like the woodp.e.c.k.e.r, they lay up their own stores of nuts, and feed on them in winter, or go hungry.

We have had very little aid from anything except the piece of bark we were studying, yet we have learned that the Californian woodp.e.c.k.e.r is a good carpenter; that he works hard at his trade; that he shows remarkable foresight in collecting his food, much ingenuity in housing it, good judgment in putting it where his enemies cannot get it, and wisdom in the plan he has adopted to give him a good supply of fresh nuts at a season when the autumn's crop is buried under the deep snow.

If I were a Californian boy, I think I should spend my time in trying to find out more about this wise woodp.e.c.k.e.r, concerning which much remains to be discovered.

IX

A RED-HEADED COUSIN