When the migrating birds return, they are attracted to this new scene. The decaying wood of fallen trees is a paradise for ants, flies, and beetles; offering to swallows, creepers, and flycatchers feasts of abundance never dreamed of in the primitive forests. Straightway, what must have been a cave swallow becomes a barn swallow; the haunter of rock ledges changes to an eave swallow; the nest in the niche of the cliff is deserted and phœbe becomes a bridgebird; cedarbirds are renamed cherrybirds, and catbirds and other low-nesting species find the blackberry patch safer than the sweetbrier vine in the deep woods. The swift leaves the lightning-struck hollow tree where owl may harry or snake intrude, for the chimney flue—sooty but impregnable.
When the great herds of ruminants disappear from the western prairies, the buffalo birds without hesitation become cowbirds, and when the plough turns up the never-ending store of grubs and worms the birds lose all fear and follow at the very heels of the plough-boy: grackles, vesper sparrows, and larks in the east, and flocks of gulls farther to the westward.
The crow surpasses all in the keen wit which it pits against human invasion and enmity. The farmer declares war (all unjustly) against these sable natives, but they jeer at his gun and traps and scarecrows, and thrive on, killing the noxious insects, devouring the diseased corn-sprouts,—doing great good to the farmer in spite of himself.
The story of these sudden adaptations to conditions which the birds could never have foreseen is a story of great interest and it has been but half told. Climb the nearest hill or mountain or even a tall tree and look out upon the face of the country. Keep in mind you are a bird and not a human,—you neither know nor understand anything of the reason for these strange sights,—these bipeds who cover the earth with great square structures, who scratch the ground for miles, who later gnaw the vegetation with great shining teeth, and who are only too often on the look out to bring sudden death if one but show a feather. What would you do?
THE SILENT LANGUAGE OF ANIMALS
What a great difference there is in brilliancy of colouring between birds and the furry creatures. How the plumage of a cardinal, or indigo bunting, or hummingbird glows in the sunlight, and reflects to our eyes the most intense vermilion or indigo or an iridescence of the whole gamut of colour. On the other hand, how sombrely clad are the deer, the rabbits, and the mice; gray and brown and white being the usual hue of their fur.
This difference is by no means accidental, but has for its cause a deep significance,—all-important to the life of the bird or mammal. Scientists have long known of it, and if we unlock it from its hard sheathing of technical terms, we shall find it as simple and as easy to understand as it is interesting. When we once hold the key, it will seem as if scales had fallen from our eyes, and when we take our walks abroad through the fields and woods, when we visit a zoological park, or even see the animals in a circus, we shall feel as though a new world were opened to us.
No post offices, or even addresses, exist for birds and mammals; when the children of the desert or the jungle are lost, no detective or policeman hastens to find them, no telephone or telegraph aids in the search. Yet, without any of these accessories, the wild creatures have marvellous systems of communication. The five senses (and perhaps a mysterious sixth, at which we can only guess) are the telephones and the police, the automatic sentinels and alarms of our wild kindred. Most inferior are our own abilities in using eyes, nose, and ears, when compared with the same functions in birds and animals.