494 THE LIVING ANIMALS OF THE WORLD 



J. Peat MilUrl 



YOUNG CUCKOO EJECTING EGG 



T/ie egg ii /lelj In position h\ the head atiil ^..ritigs 



[Btiih 



cunning, and the mutual co-operation of both the male and his — at least temporary — wife ; 

 hence the disguise. The plan of execution very frequently adopted is for' the male to hover 

 over the treasure-house of the intended foster-parents hawk-wise. This is sure to call forth an 

 attack from the poor little wretches threatened, which ends in an apparentl}' hasty retreat of 

 the marauder, followed by his fearless assailants. No sooner is the coast clear, however, than 

 the wily female, taking her egg in her beak, slips quietly up to the nest and deposits her burden. 



Let us imagine that this home so latel)' threatened is that of the modest little hedge- 

 sparrow, and take a peep during the absence of the owners, after quiet has established itself 

 once again. Lying side by side with the tiny sky-blue eggs of the hedge-sparrow we should 

 find the relatively large, greyish-green or reddish-grey egg of the cuckoo. What a contrast ! 

 If the hedge-sparrows notice this too, the}' evidently do not mind, for they invariably hatch it 

 with their own. 



But some birds are not so accommodating as this, and would ruthlessly destroy or reject 

 any egg surreptitiously introduced into the nest. Consequently more deception has to be 

 practised. The hawk-like garb still serves its purpose to draw off the intended dupes from 

 the nest; but this is not enough, for to deposit an egg of the normal cuckoo type would be 

 worse than useless, since it would meet with instant destruction on the return of the owners 

 of the nest. But the cuckoo, strange to say, has proved equal to the occasion, and meets 

 the difficulty by laying an egg to match those in the nest. The Redstart, Wagtail, Sedge- 

 warbler, Red-backed Shrike, and Meadow-pipit may be cited as instances of — shall we say 

 exclusive? — birds which must be circumvented by " colourable imitations." Perhaps the most 

 wonderful of the cuckoo successes in this direction is the imitation of the redstart's egg, 

 which is blue. 



Naturally these facts have given rise to much speculation, but even now we cannot regard 

 the discussion as finally settled. Some ornithologists held that the egg of every individual 

 cuckoo was subject to great variations, and that the place of deposit of each egg was determined 



