Fear in Birds: 9! 
while their own young, if the parasite has allowed 
any to surviye 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 ombu 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 ita 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 
cuttural noises and strange gestures made a pom- 
pous declaration of amorous feelings, the dove 
would strike vigorously at its undesirable lover, 
