This practice of the birds is not so uncommon as it might at first seem.  It is indeed almost an invariable rule among all land birds.  With woodpeckers and kindred species, and with birds that burrow in the ground, as bank swallows, king-fishers, etc., it is a necessity.  The accumulation of the excrement in the nest would prove most fatal to the young.

But even among birds that neither bore nor mine, but which build a shallow nest on the branch of a tree or upon the ground, as the robin, the finches, the buntings, etc., the ordure of the young is removed to a distance by the parent bird.  When the robin is seen going away from its brood with a slow, heavy flight, entirely different from its manner a moment before on approaching the nest with a cherry or worm, it is certain to be engaged in this office.  One may observe the social sparrow, when feeding its young, pause a moment after the worm has been given and hop around on the brink of the nest observing the movements within.

The instinct of cleanliness no doubt prompts the action in all cases, though the disposition to secrecy or concealment may not be unmixed with it.

The swallows form an exception to the rule, the excrement being voided by the young over the brink of the nest.  They form an exception, also, to the rule of secrecy, aiming not so much to conceal the nest as to render it inaccessible.

Other exceptions are the pigeons, hawks, and water-fowls.

But to return.  Having a good chance to note the color and markings of the woodpeckers as they passed in and out at the opening of the nest, I saw that Audubon had made a mistake in figuring or describing the female of this species with the red spot upon the head.  I have seen a number of pairs of them, and in no instance have I seen the mother bird marked with red.

The male was in full plumage, and I reluctantly shot him for a specimen.  Passing by the place again next day, I paused a moment to note how matters stood.  I confess it was not without some compunctions that I heard the cries of the young birds, and saw the widowed mother, her cares now doubled, hastening to and fro in the solitary woods.  She would occasionally pause expectantly on the trunk of a tree and utter a loud call.

It usually happens, when the male of any species is killed during the breeding season, that the female soon procures another mate.  There are, most likely, always a few unmated birds of both sexes within a given range, and through these the broken links may be restored.  Audubon or Wilson, I forget which, tells of a pair of fish hawks, or ospreys, that built their nest in an ancient oak.  The male was so zealous in the defense of the young that he actually attacked with beak and claw a person who attempted to climb into his nest, putting his face and eyes in great jeopardy.  Arming himself with a heavy club, the climber felled the gallant bird to the ground and killed him.  In the course of a few days the female had procured another mate.  But naturally enough the stepfather showed none of the spirit and pluck in defense of the brood that had been displayed by the original parent.  When danger was nigh he was seen afar off, sailing around in placid unconcern.