Then there is the beaver, whose tail I am convinced is a trowel. I know of no naturalist who has mentioned this, but such negative evidence is of little weight. The beaver, as everybody knows, is a builder, who cuts down trees and piles log upon log until he has raised a solid, domed cabin from seven to twenty feet in diameter, which he then plasters over with clay and straw. If he does not turn round and beat the work smooth with his tail, then I require to know for what purpose he carries that broad, heavy, and hard tool behind him.
How few even among lovers of Nature know why a frog has no tail! The reason-is simply that it used that organ up when it was in want. In early life, as a jolly tadpole, it had a flourishing tail to swim with, and gills for breathing water, and an infantile mouth for taking vegetable nourishment. But when it began to draw near to frog's estate, serious changes were required in its structure to fit it for the life of a land animal. Four tiny legs appeared from under its skin, the gills gave place to air-breathing lungs, and the infant lips to a great, gaping mouth. Now, during this "temporary alteration of the premises" all business was of necessity stopped. The half-fish, half-frog could neither sup like an infant nor eat like a man. In this extremity it fed on its own tail—absorbed it as a camel is said to absorb its hump when travelling in the foodless desert—and so it entered on its new life without one.
Aeronautics have changed the whole perspective of life for birds, as they may for us shortly; so it is no surprise to find that birds have, almost with one consent, converted their tails into steering-gear. A commonplace bird, like a sparrow, scarcely requires this except as a brake when in the act of alighting; but to those birds with which flight is an art and an accomplishment, an expansive forked or rounded tail (there are two patents) is indispensable. We have shot almost all the birds of this sort in our own country, and must travel if we would enjoy that enchanting sight—a pair of eagles or a party of kites gone aloft for a sail when the wind is rising, like skaters to a pond when the ice is bearing. For an hour on end, in restful ease or swift joy, they trace ever-varying circles and spirals against the dark storm-cloud, now rising, now falling, turning and reversing, but never once flapping their widespread pinions.
How is it done? How does the Shamrock sail? Watch, and you will see. When the wind is behind, each stiff quill at the end of the wing stands out by itself and is caught and driven by the blast; but as the bird turns round to face the gale, they all close up and form a continuous mainsail, close-hauled. And all the while the expanded tail is in play, dipping first at one side and then at the other, and turning the trim craft with easy grace "as the governor listeth."
Besides ground birds, like the quail, there are some eccentrics, such as Jenny wren, which have despised their tails, and there are specialists also which require them for other purposes than flying. The woodpecker's tail is quite useless as a rudder, for he is a woodman and has altered and adapted it for a portable stool to rest against as he plies his axe.
But that man must be very blind to the place which birds have taken in the progress of civilisation who can suppose it possible that they should think only of utility in such a question as the disposal of their tails. It is a common notion among those who have acquired some smattering of the theory of evolution that fishes developed into reptiles, reptiles into birds, and birds into beasts; but this is as wrong as it could be. Whatever the genealogy of the beasts may be, they certainly were not evolved from birds, and are in many respects not above them but below them. These are two independent branches of the tree of living forms, as the Greeks and Romans were branches of the stock of Japheth. The beasts may stand for the conquering Romans if you like, but the birds are the Greeks, and have advanced far beyond them in all emotional and artistic sensibility. They worship in the temple of music and beauty. And, like ourselves, they have found no subject so worthy of the highest efforts of art as their own dress. But the clothing of the body must conform more or less to the figure, and so, for a field in which invention and fancy may sport untrammelled, a lady turns to her hat and a bird to its tail. And by both, with equal heroism, every consideration of mere comfort, convenience, health, or safety is swept aside in obedience to the higher aim. Is this only a flippant jocularity, or is there here in very truth some profound law of the mind revealing itself in spheres seemingly so disconnected?
Look at a peacock. Its train, by the way, is a false tail, like the chignon of twenty years ago, or the fringe of the present day; the true tail is under it, and serves no purpose but to support it. Now the peacock lives on the ground, among scrub and brushwood, haunted by jackals and wild cats. They, like soldiers in khaki, reconnoitre him in a uniform expressly designed to elude the eye, but he flaunts a flag resplendent with green and gold. And when his one chance of life lies in springing nimbly from the ground and committing himself to his strong wings, he must lift and carry this ponderous paraphernalia with him. And the terrible Bonelli's eagle is soaring above. But all is risked proudly for the sake of the morning hour in the glade where the ladies assemble. And the peacock is only one of many. Not to mention the lyre bird, the Argus pheasant, the bird of paradise, and other splendid examples, there are common dicky-birds which point the moral and adorn the tail as emphatically.