Fear in Birds'. 91 



while their own young, if the parasite has allowed 

 any to survive in the nest, are crouching down in 

 the greatest fear. After the cow-bird has left the 

 nest it is still stupidly tame, and more than once I 

 have seen one carried off from its elevated perch by 

 a milvago hawk, when, if it had understood the 

 warning cry of the foster parent, it would have 

 dropped down into the bush or grass and escaped. 

 But as soon as the young cow-birds are able to shift 

 for themselves, and begin to associate with their 

 own kind, their habits change, and they become 

 suspicious and wild like other birds. 



On this point — the later period at which the 

 parasitical young bird acquires fear of man — and 

 also bearing on the whole subject under discussion, 

 I shall add here some observations I once made on 

 a dove hatched and reared by a pigeon at my home 

 on the pampas. A very large ombii tree grew not 

 far from the dove-cote, and some of the pigeons 

 used to make their nests on the lower horizontal 

 branches. One summer a dove of the most common 

 species, Zenaida maculata, in size a third less than 

 the domestic pigeon, chanced to drop an egg in one 

 of these nests, and a young dove was hatched and 

 reared ; and, in due time, when able to fly, it was 

 brought to the dove-cote. I watched it a great deal, 

 and it was evident that this foster-young, though 

 with the pigeons, was not nor ever would be of them, 

 for it could not take kindly to their flippant flirty 

 ways. Whenever a male approached it, and with 

 guttural noises and strange gestures made a pom- 

 pous declaration of amorous feelings, the dove 

 would strike vigorously at its undesirable lover, 



