Work of Sapsucker.
Here is a specimen of the yellow-bellied sapsucker’s work which I picked up under the tree from which it had fallen. We do not need to inquire whether the tree was injured by its falling, for we know that the loss of sound and healthy bark is always a damage. Was this sound bark? Yes, because it is still firm and new. The sap in it dried quickly, showing that neither disease nor worms caused it to fall; it is clean and hard on the back, showing that it came from a live tree, not from a dead, rotting log.
How do I know that a bird caused it to fall? The marks are precisely such as are always left by a woodpecker’s bill. How do I know that it was a sapsucker’s work? Because no other woodpecker has the habit which characterizes the sapsucker, of sinking holes in straight lines. The sapsuckers drill lines of holes sometimes around and sometimes up and down the tree-trunk, but almost always in rings or belts about the trunk or branches. A girdle may be but a single line of holes, or it may consist of four or five, or more, lines. Sometimes a band will be two feet wide; and as many as eight hundred holes have been counted on the trunk of a single tree. Such extensive peckings, however, are to be expected only on large forest trees. Most fruit and ornamental trees are girdled a few times about the trunk, and about the principal branches just below the nodes, or forks.
Why did the bird dig these holes? There are three things that he might have obtained,—sap, the inner bark, and boring larvæ. Some naturalists have suggested a fourth as possible,—the insects that would be attracted by the sap.
We will see what the piece of bark tells us. It is four and a half inches long, by an inch and a half wide, and its area of six and three fourths square inches has forty-four punctures. Does this look as if the bird were digging grubs? Do borers live in such straight little streets? The number and arrangement of the holes show that he was not seeking borers, while the naturalists tell us that he never eats a borer unless by accident. What did he get? Undoubtedly he pecked away some of the inner bark. All these holes are much larger on the back side of the specimen than on the outer surface. While the damp inner bark would shrink a little on exposure to the air, we know that it could not shrink as much as this; and investigation has shown that the sapsucker feeds largely on just such food, for it has been found in his stomach. Two other possible food-substances remain,—sap and insects. We know that the sapsucker eats many insects, but it is impossible to prove that he intended these holes for insect lures. Sap he might have gotten from them, if he wished it. We know that the white birch is full of excellent sap, from which can be made a birch candy, somewhat bitter, but nearly as good as horehound candy. The rock and red maples and the white canoe birch are the only trees in our Northern forests from which we make candy. A strong probability that our bird wanted sap is indicated by the arrangement of the holes. Usually he drills his holes in rings around the tree-trunk, but in this instance his longest lines of holes are vertical. If our sapsucker was drilling for sap, he arranged his holes so that it would almost run into his mouth, lazy bird!
Our piece of bark has taught us:—
That the sapsucker injured this tree.