That the effect of his work upon the tree was apparently injurious, as it is the only cause assigned 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 woodpeckers 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 woodpecker’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 quantity 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 woodpecker except at time of nesting, and most woodpeckers 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 ambassadors who do not please their majesties. What shall we do with him, the only black sheep in all the woodpecker flock? Let him alone, unless we are positively sure that we know him from every other kind of woodpecker. The damage he does is trifling compared with what we should do if we made war upon other woodpeckers for some supposed wrong-doing of the sapsucker.
VIII
EL CARPINTERO
In California and along the southwestern boundary of the United States lives a woodpecker 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 fashion 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 butt 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.
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,2 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.
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 woodpecker’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 woodpeckers 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 appetite. I have experimented on this piece of bark, using a woodpecker’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 woodpecker 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.
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 woodpecker 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 woodpecker’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 butt. 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 woodpecker. Every other acorn is as hard, shining, 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 woodpecker, over a large part of his range, is a mountain bird. Though we think of California as the land of sunshine, 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 woodpecker’s stores out of his pine-tree pantry than to pick up honest acorns of their own. So, like the woodpecker, 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 woodpecker 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 woodpecker, concerning which much remains to be discovered.
IX
A RED-HEADED COUSIN
Besides his half-brothers, the narrow-fronted and ant-eating woodpeckers, the Carpenter has a numerous family of cousins, – the red-headed, the red-bellied, the golden-fronted, the Gila,3 and the Lewis’s woodpeckers. 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 woodpecker of the middle West. This well-known cousin is the red-headed woodpecker, 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.
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 woodpecker 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 grasshoppers. 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 grasshoppers? 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 grasshoppers, still alive, but wedged in so tightly they could not escape. He also found other hiding-places all full of grasshoppers, and discovered that the woodpeckers lived upon these stores nearly all winter.
But it is not grasshoppers only that the red-head hoards, though he is very fond of them. In some parts of the country it is easier to find nuts than to find grasshoppers, 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 woodpecker 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.
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 accumulations 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 shingles on the roofs; if a board was sprung out, the space 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 hoard.
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 woodpeckers have hoarding-places. We know that the sapsucker eats beechnuts, and the downy and the hairy woodpeckers also; that the red-bellied woodpecker and the golden-winged flicker eat acorns; and I have seen the downy woodpecker 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.
It is known that the Lewis’s woodpecker occasionally shows signs of a hoarding instinct. It was recently noted that in the San Bernardino Mountains of California the Lewis’s woodpecker, after driving away the smaller Californian woodpeckers, 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 woodpecker that had a large quantity of acorns shelled and broken into quarters, on which he was feeding. This woodpecker was identified beyond a doubt as the Lewis’s woodpecker. So we begin to suspect that the habit of storing up food is not an uncommon one among the woodpeckers.