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 [Pg 323] 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.