I feared that the hedge-sparrows would desert the nest, which now surely was but an empty mock, with its one alien egg. In the ordinary way one will find the cuckoo’s egg amongst the others, in some cases exchanged for one belonging to the nest. When the young cuckoo is hatched, he displays great irritation if anything touches his back, and will not rest till the other occupants of the nest, whether eggs or fledgelings like himself, are cast out. The parent birds show an indifference to these unfortunates, and all their efforts are for the intruder. Thus I was considerably surprised to find that the female sparrow was sitting on the strange egg. Had I, before the tragedy, taken the four eggs away, and placed instead an egg of a robin or a thrush, it is practically certain that it would have been ignored. Both parent birds were near when the female cuckoo was laying her egg, and kept flying round the nest, accompanied by a robin who may have been, like myself, a curious spectator in this domestic affair. Five weeks afterwards the young cuckoo was many times the size of his wretched foster parents, and throughout the long days of June they worked in the hedges, seeking caterpillars, grubs, and spiders for their querulous nestling. The migration of the young cuckoo in August is helped by a most interesting series of ingenious frauds. The old cuckoos depart for the south in July, and the younger birds making their way independently, day by day, are directed only by instinct. But the baby cannot feed itself (or probably will not, being a born parasite), and the poor little pair of birds who have slaved for it will not follow him when the wanderlust comes into his blood. The method of cadging a meal is as extraordinary as it is utterly callous. The cad will fly ten or twelve miles a day in a southerly direction. At intervals he cries in an infantile, screaming voice. There is bound to be near a pair of birds with young, and should they hear the cry, they leave their own children and go and feed the wide-mouthed impostor. No small birds, _with fledgelings_, appear to be able to resist the call. They go and feed him. The fact that the young cuckoo bears a resemblance to a kestrel hawk, both in flight and colour, makes their charity all the more mysterious. Down to the south he wanders, his wings getting stronger every day, until the time comes when the sea shines in the distance, and his long journey begins. And throughout the days of his English stay, he lives on the foolish and charitable ones among the smaller, insectivorous birds.