Birds by Land and Sea 



ends they serve which will call for explanation by 

 any one attempting to elucidate the problem. 



Thus, the formation of the bill of the cuckoo is 

 cited as correlated with the abnormally small size of 

 the egg it lays, the bird being thereby enabled to 

 deposit it with its bill in situations in which it would 

 be impossible for it to lay the egg directly. Further, 

 correspondence is found between the smallness of 

 the egg and the fact that it is almost always in the 

 nests of small birds that it is deposited ; between the 

 circumstance that the cuckoo distributes its eggs 

 singly, and the result that it thus obviates the 

 encounter in the same nest of two of its young bent 

 upon mutual destruction ; between its habit of de- 

 positing its egg at a time when the earlier eggs of 

 the brood of the foster parent have been laid, some- 

 times throwing out all, at others a portion, of the 

 native eggs, and the accruing advantage to its young 

 of being early in possession of the nest, and ade- 

 quately equipped to eject its fellow nestlings and 

 appropriate the food which, if divided among all, 

 would prove insufficient to meet the needs of so 

 large and greedy a bird ; and, finally, between the 

 singular depression in the back of the young bird, 

 which assists it in ejecting its fellow nestlings from 

 the nest, and the ejecting impulse itself. 



If the bird is to convey its egg at all, it would 

 not seem strange that it should employ its bill for 

 this purpose, seeing that the bill is always used by 

 birds in arranging their eggs, and as a means of 



150 



