116 A PHILOSOPHER WITH NATURE 



varjdng from simple carelessness to the stage in 

 which the parasitic habit is almost as well developed 

 as in our own cuckoo. Some of the birds only show 

 a disposition to lay their eggs carelessly about, 

 occasionally dropping them in other birds' nests. 

 In others the nest-building instinct has in great 

 measure disappeared. The birds congregate together 

 in flocks, and they often lay their eggs in heaps, 

 so that only a small proportion are hatched, the 

 parents assisting indiscriminately in the task of 

 hatching the eggs and feeding the young. Lastly, 

 in one species the cuckoo's habit is developed. A 

 single egg is laid in the nests of other birds ; the 

 young stranger monopolizes the attention of the 

 foster-parent ; and though it is said not to eject 

 its fellow-nestlings, like the cuckoo, these generally 

 come by their death in consequence of its presence. 

 The one noteworthy pecuharity which the cow-bird 

 is said to have besides in common with the cuckoo 

 is its gluttony. The bird is generally spoken of as 

 possessing an insatiable appetite. 



Returning now to our own cuckoo, there is one 

 pecuharity of the young bird which seems very 

 significant. It appears open to question whether 

 the true meaning of the habit of ejecting its feUows 

 from the nest has not been overlooked by observers. 

 That the young cuckoo could have acquired this 

 habit merely in order to be able to turn out the 

 weak and small fellow-nestlings with which it is 

 usually associated seems hard to conceive. These 

 would beyond doubt be either starved or smothered 

 in any case (as the companions of the American 

 cow-bird appear to be) and it seems almost impossible 

 that natural selection should develop so deep-seated 



