None of the owls ever digest the bones and feathers or hair of their prey; but these materials get packed into balls in the stomach, and after a time are coughed up and thrown away. Very often large quantities of these "pellets" are found in hollow trees in which owls have been roosting, more than a bushel having been taken from a single tree, and by examining them one may learn the character of the bird's daily fare. The birds do not make a nest, but lay their eggs on a heap of these pellets instead; and they have an odd way of laying them at intervals, so that sometimes half-fledged little ones, newly hatched little ones, and freshly laid eggs may all be found together.
When the young owls are waiting for their parents to return with a mouse, they always get very much excited and make most odd noises, something like loud hisses followed by loud snores. And when at last one of the old birds returns with a mouse in its talons the outcry grows louder than ever.
One of the oddest members of the family is the burrowing owl, or coquimbo, as the South American form is known. This inhabits only the open plains of Western North America and Southern South America, and as it can find no trees or rocky niches in which to nest, it scratches out shallow burrows in little banks of earth, or takes possession of the deserted burrows of some digging animal. It is therefore a constant citizen of the "towns" of the prairie-dogs of the North and viscachas of the South, where numbers of burrowing owls may sometimes be seen, some hunting about for beetles and grasshoppers, on which they chiefly feed, and others sitting at the entrances of the burrows and surveying the surrounding country. They are not at all timid, and if a man approaches them they will remain where they are until he is quite close, bobbing up and down from time to time as though they were politely bowing to him. If he continues to walk toward them they will rise into the air, fly two or three times round his head, screaming loudly as they do so, and then settle down on another mound a few yards away and bow to him again. But if he walks round them instead they will turn their heads to look after him, without moving their bodies, until one would almost think that they would twist them off altogether.
When neither prairie-dogs nor viscachas live in the neighborhood, these queer little owls will sometimes take up their quarters in the burrow of a wolf, a fox, or a badger. They make a very rough nest of grass and feathers, in which they lay from six to eleven white eggs.
CHAPTER XXI
CUCKOOS, NIGHTJARS, HUMMING-BIRDS, WOODPECKERS, AND TOUCANS
In Europe the cuckoo is one of the most familiar and well-known birds, and every one recognizes its note, and regards it as a sure sign that summer is near. The bird usually reaches England about the second week in April, and very soon after that time the cock bird may be heard uttering his cry, which is one of the most familiar sounds of the country, until two months later. Then the bird's voice breaks, and after crying "cuck-cuck-cuck-oo" for a few days, instead of the simple "cuckoo," he becomes quite dumb, and is quite unable to utter his note again until the following spring.
This cuckoo is famous for its singular habit of placing its egg in the nest of some other bird, instead of making a nest of its own. The hen bird seems, first of all, to lay her egg on the ground; then, picking it up in her beak, she flies off to look for a suitable nest in which to put it. Having found one, she waits her opportunity, when the occupant is absent, and then slips in the egg and flies away. The owner of the nest, strange to say, hardly ever seems to notice when she comes back that there is a strange egg among her own, although very often it is not in the least like them in color and markings. So before very long a young cuckoo is hatched out, together with her own little ones. Then on the very day of its birth the cuckoo seems to make up its mind that before long there will be no room in the nest for any one but itself, and actually pushes all its little foster brothers and sisters over the side, one after the other! And, strange to say, the mother bird does not seem to mind, but just gives all the food which her own young would have eaten to the cuckoo, and takes the greatest care of it in every way until it is able to fly.
The cuckoo family is a large and varied one, with representatives in all parts of the world, and few of them show this extraordinary disposition to impose upon their neighbors, though all are careless home-makers. In the United States we have two kinds of cuckoos, the black-billed and the yellow-billed, which have much the same slim form and plain yet elegant dress as their European cousin, but a different note, uttering a loud rattling cry instead of the soft cuck-oo; and both of these make nests, lay eggs in them, and rear their young as faithfully as other birds. The nests, however, are merely loose platforms of twigs set among the branches of some small tree, through which, often, the greenish-blue eggs are distinctly visible.