Although the eagle has the emblematic place of honor in the United States, the downy woodpecker is distinguished as the most useful bird citizen. Of the eight hundred and three kinds of birds in North America, his services are most helpful to man. He destroys destructive forest insects. Long ago Nature selected the woodpecker to be the chief caretaker—the physician and surgeon—of the tree world. This is a stupendous task. Forests are extensive and are formed of hundreds of species of trees. The American woodpeckers have the supervision of uncounted acres that are forested with more than six hundred kinds of trees.

With the exception of the California big tree, each tree species is preyed upon by scores, and many species by hundreds, of injurious and deadly insects. Five hundred kinds of insects[Pg 194] are known to prey upon the oak, and a complete count may show a thousand kinds. Many of these insects multiply with amazing rapidity, and at all times countless numbers of these aggressive pests form warrior armies with which the woodpecker must constantly contend.

In this incessant struggle with insects the woodpecker has helpful assistance from many other bird families. Though the woodpecker gives general attention to hundreds of kinds of insects, he specializes on those which injure the tree internally,—which require a surgical operation to obtain. He is a distinguished specialist; the instruments for tree-surgery are intrusted to his keeping, and with these he each year performs innumerable successful surgical operations upon our friends the trees.

Woodpeckers are as widely distributed as forests,—just how many to the square mile no one knows. Some localities are blessed with a goodly number, made up of representatives from three or four of our twenty-four woodpecker species. Forest, shade, and orchard trees receive their impartial attention. The annual[Pg 195] saving from their service is enormous. Although this cannot be estimated, it can hardly be overstated.

A single borer may kill a tree; so, too, may a few beetles; while a small number of weevils will injure and stunt a tree so that it is left an easy victim for other insects. Borers, beetles, and weevils are among the worst enemies of trees. They multiply with astounding rapidity and annually kill millions of scattered trees. Annually, too, there are numerous outbreaks of beetles, whose depredations extend over hundreds and occasionally over thousands of acres. Caterpillars, moths, and saw-flies are exceedingly injurious tree-pests, but they damage the outer parts of the tree. Both they and their eggs are easily accessible to many kinds of birds, including the woodpeckers; but borers, beetles, and weevils live and deposit their eggs in the very vitals of the tree. In the tree\'s vitals, protected by a heavy barrier of wood or bark, they are secure from the beaks and claws of all birds except Dr. Woodpecker, the chief surgeon of the forest. About the only opportunity that[Pg 196] other birds have to feed upon borers and beetles is during the brief time they occupy in emerging from the tree that they have killed, in their flight to some live tree, and during their brief exposure while boring into it.

Beetles live and move in swarms, and, according to their numbers, concentrate their attack upon a single tree or upon many trees. Most beetles are one of a dozen species of Dendroctonus, which means "tree-killer." Left in undisturbed possession of a tree, many mother beetles may have half a million descendants in a single season. Fortunately for the forest, Dr. Woodpecker, during his ceaseless round of inspection and service, generally discovers infested trees. If one woodpecker is not equal to the situation, many are concentrated at this insect-breeding place; and here they remain until the last dweller in darkness is reached and devoured. Thus most beetle outbreaks are prevented. Now and then all the conditions are favorable for the beetles, or the woodpecker may be persecuted and lose some of his family; so that, despite his utmost efforts, he fails to[Pg 197] make the rounds of his forest, and the result is an outbreak of insects, with wide depredations. So important are these birds that the shooting of a single one may allow insects to multiply and waste acres of forest.

During the periods in which the insects are held in check the woodpecker ranges through the forest, inspecting tree after tree. Many times, during their tireless rounds of search and inspection, I have followed them for hours. On one occasion in the mountains of Colorado I followed a Batchelder woodpecker through a spruce forest all day long. Both of us had a busy day. He inspected eight hundred and twenty-seven trees, most of which were spruce or lodge-pole pine. Although he moved quickly, he was intensely concentrated, was systematic, and apparently did the inspection carefully. The forest was a healthy one and harbored only straggling insects. Now and then he picked up an isolated insect from a limb or took an egg-cluster from a break in the bark on a trunk. Only two pecking operations were required. On another occasion I watched a hairy woodpecker[Pg 198] spend more than three days upon one tree-trunk; this he pecked full of holes and from its vitals he dragged more than a gross of devouring grubs. In this case not only was the beetle colony destroyed but the tree survived.
WOODPECKER HOLES IN A PINE INJURED BY LIGHTNING WOODPECKER HOLES IN A PINE INJURED BY LIGHTNING

Woodpecker holes commonly are shallow, except in dead trees. Most of the burrowing or boring insects which infest living trees work in the outermost sapwood, just beneath the bark, or in the inner bark. Hence the doctor does not need to cut deeply. In most cases his peckings in the wood are so shallow that no scar or record is found. Hence a tree might be operated on by him a dozen times in a season, and still not show a scar when split or sawed into pieces. Most of his peckings simply penetrate the bark, and on living trees this epidermis scales off; thus in a short time all traces ............