Fig. 208.—House Sparrows. (× ⅕.) Fig. 209.—The Swift. (× ⅙.)
57. THE SWIFT AND THE CUCKOO.
1. The swift.—Distinguish the swift from the swallow by its larger size, its sooty black colour (except for the dull white of the throat), and its long, bowed wings. In what respect does the swift resemble the swallow? Watch for the appearance of swifts about the end of April. Do the birds arrive singly, in pairs, or in flocks? Notice the rapid turns and twists of the flying bird. Does it as a rule fly near the ground, or at somewhat great heights? Have you ever noticed the bird perching, or settling on the ground? Have you seen it clinging to walls with its feet? Were these the walls of houses or barns, or of high towers? What actions would lead you to suppose that the nests are built in high towers? Are more swifts to be seen in the evening, or during the day? Can you explain this? Watch during the first half of August, and make a note of the day on which swifts were last seen.
2. The cuckoo.—What is the earliest date on which you have heard the cuckoo? Imitate the cry by putting your hollowed hands together and blowing between the thumbs. With practice you will be able to deceive the bird into thinking that another cuckoo is present, and it will approach near enough to be seen distinctly. Estimate the size of the bird, and write down a careful description of its form, colouration, and method of flight. Try to see that two of its toes point forwards and two backwards. Have you ever seen cuckoos mobbed by small birds?
Carefully examine as many nests of small birds as possible, and try to find one containing an egg slightly larger than the rest and perhaps differently coloured. This will probably be a cuckoo’s egg. Visit the nest at frequent intervals, both before and after the hatching of the eggs, and write descriptions of the eggs, the appearance and size of the young birds, what becomes of each, and the behaviour of the old birds. What is the latest date on which you have heard the cuckoo?
The swift.—Though the swift bears a strong general resemblance to the swallow, the two birds are not at all closely related, but belong to different orders. The swallow, like all other passerine birds ([p. 320]), has 12 tail-feathers, and its first toe is separately movable and directed backwards. The swift, on the other hand, has only 10 tail-quills, and all its toes point forwards. There are, however, more obvious differences, which readily enable one bird to be distinguished from the other, even at a distance. The swift is, with the exception of a dull-white patch on the throat, of a sooty black hue over all the body, and in flight its long and powerful wings take the form of a bent bow ([Fig. 209]). The swallow flies in bold, sweeping curves, while the more rapid swift turns sharply in the air, in pursuit of the flying insects upon which it feeds, in a manner suggestive of the flight of a bat. While, again, the swallow flies much near the ground, the swift is usually seen at greater heights. The harsh scream of the swift is, moreover, in marked contrast with the swallow’s pleasing song.
Swifts do not willingly alight on the ground, even to collect materials for their nests, nor do they perch on trees or roofs, the arrangement of their toes being quite unsuitable for either action, and the length of the wings being such that, even with toes of the normal type, walking would be almost impossible. The nest, a somewhat rude structure of grass and feathers, is generally built in high towers or other tall buildings. The eggs are two in number; they are more conical in shape than those of the swallow, and, as the position of the nest renders them independent of protective colouration, are white. The hen-bird sits on them during the day, but generally leaves the nest and flies abroad in the evening to hunt for insects. Only one brood is reared, and the birds take their departure early in August, to spend the winter in South Africa or Madagascar.
The cuckoo.—The cuckoo is placed by naturalists, not among the passerine birds, but in the order to which the swift belongs. The reasons for this cannot be fully considered here, but it may be mentioned that the cuckoo has only 10 tail-feathers, and that it differs from all passerine birds in having its fourth toe, as well as the first, directed backwards, the second and third pointing forwards ([Fig. 210]).
The cuckoo has a total length of about 14 inches. The upper surface of the body, and the throat, are grey; the rest of the lower surface is white, crossed with black bars. The wings are large and powerful, and the thighs are covered with long feathers. In general appearance, as well as in manner of flight, the cuckoo bears a great resemblance to a hawk, which may perhaps be the reason why small birds so often join forces and attack it. A keen-eyed observer will, however, at once distinguish the birds by the head and the bill, both of which are markedly longer in the cuckoo than in the hawk. Cuckoos arrive here in April, the males usually appearing first. The well-known call, to which the bird owes its name, is uttered by the male only; the voice of the female is quite different, and is often compared to the sound of bubbling water. The cuckoo feeds entirely upon insects; it is believed to be the only bird which eats the hairy caterpillar of the tiger-moth ([p. 369]).