Moreover, the land birds cannot sleep safely on the ground, where weasels and stoats, foxes and wild cats, prowl by night in search of prey; they must take their rest on the boughs of the tall trees and cling on by their toes even when they are in the deepest slumber. This they could not do if they had the stumpy cushioned feet of the ostrich, the webbed feet of the duck, or the flat three-toed feet of the waders. It is the fourth toe turned backwards, and growing very long in many of the perching birds, which gives them their grasp; while a special muscle, beginning behind the thigh (th, [Fig. 33], [p. 126]), coming round over the front of the knee (k), and then passing behind the heel (h), and on to the toes, keeps them bent. Picture for a moment this muscle sending its cords or tendons from behind the leg over the knee, and then drawn back by the heel, and you will see that the more heavily the bird sleeps, pressing upon its legs, the more the knees will be bent forward, the tighter the cord must be stretched, and the stronger the grasp will be upon the bough.

Again, as to food, the land birds will be more closely pressed than those which can at all times fish in the sea. There is great scarcity of land food in the winter, while in summer whole flocks of newly-born fledgelings are clamouring for their daily bread. So we shall find that every kind of eatable thing is turned to account, and we have among land birds seed-eaters, vegetable-feeders, and fruit-eaters; insect-devourers, and feeders on slugs and worms and snails; and flesh-eaters which feed on other birds, or on mice, bats, and larger animals; while large flocks of birds of all kinds visit different parts of the earth in the various seasons, going north in summer to build their nests, and south in winter, in search of food. All these birds live chiefly in the air; while on the ground there are the scratchers—fowls, partridges, turkeys, and grouse, which rake out the hidden grains, and rarely rise into the air except when they are frightened, or to roost on the trees at night. And between these ground birds and the true tree birds we have the doves and pigeons, some of which feed on fallen seed and grains, and others on fruit. And each and all of these birds have some difference in beak and claw, in their manner of nest building and rearing their young, and in their habits and ways, which enables them to make the most of their lives.

* * * * *

Even nest building does not come to all land birds by nature, and, as we shall see, it depends very largely on the habits and the structure of the builders. Thus the Partridges, and their relations the Pheasants and Grouse, lay their eggs in the thick grass of the meadows or among the heather, and at most sometimes scratch together a few dry grass blades for a bed. In this they remind us much of the ostrich family, which also scrape a hole in the ground for their eggs and scratch food for their children; and in fact there is a group of curious heavily-flying birds, called Tinamous, in South America, which are so like quails and partridges on the one hand, and ostriches on the other, that they lead us to wonder whether it was not from the ancestors of such birds as these in ancient times that the heavy running birds started on one road, while the lighter and swifter birds took to the wing.

The wings of all the scratching birds are even now short and round, and their flight is feeble. Their chief home is on the ground, where they crouch among the thick herbage when the keen-eyed hawk is hovering overhead, never taking to their wings till no other chance is left them. The mother partridge runs many dangers as she sits upon her dark-coloured eggs in some sheltered spot, for weasels and stoats will attack her and steal her eggs if she leaves them for a moment, or kill her herself if they can take her unawares in the dark night. She could never hope to rear her young ones if they did not come out of the egg well covered with down, and able to run and pick by her side while she and the father scratch the ground with their short blunt claws to get ant-cocoons, and later on worms and insects for them.

Yet so well does scratching answer, in getting at buried food such as other birds cannot find, that there are a large number of these ground birds all over the world. The Guinea fowls of Africa, the spurred Peacocks, Pheasants, and Jungle fowls of India (from which last our tame fowls probably come), the wild Turkeys of America, the Quails which live in all parts of the old world from Australia to England, and the Ptarmigans of our northern countries, which put on their white plumage in winter—all these show how advantage has been taken of every nook in which ground birds could find shelter. We find them hiding in thick jungles and shady woods, or even in open ground among high grass and corn, scratching mother earth for their daily food; washing not in water but actually in the dust, by rolling in it, and then shaking it off; escaping many dangers by wearing a plumage very much the same in colour as the different grasses and leaves among which they hide; and feeding on insects, worms, and seeds, and whatever they can find upon the ground or under it.

Fig. 41.

Brush turkeys[99] and their egg mounds.

And when we travel far off to Australia, we find ground birds which do not even sit on their eggs, nor take care of their young, but leave them as reptiles do to be hatched in the sun. The Brush-turkeys and Megapodes of Australia and the islands near, and the Maleos of Celebes—all of them scratching birds—come out of the thick jungle and lay their brick-red or pale-coloured eggs on the shore, never taking any more notice of them. The maleos simply scratch a hole in the sand and bury the eggs, the brush turkeys and megapodes[100] scratch together all kinds of rubbish and dead leaves, carrying them in their long curved claws, and adding them to the heap till they have made a mound sometimes more than seven or eight feet high, and twenty feet across at the base; an astounding size, when we consider that the brush turkeys are not nearly as large as a good-sized turkey, and the megapodes not larger than hens. It is to these mounds that the mothers come about every ten days, and lay an egg upright, till each has laid eight or nine, and then she comes no more; but after many weeks the little chicks work their way out fully fledged, and fly away to get their own living. The probable reason, Mr. Wallace tells us, for this curious habit of mound-building, is that the eggs are so large that the mother can only lay one every ten days, so that if she sat upon them she would be worn out with fatigue and want of proper food before they were all laid and hatched.