Fear in Birds. 93 
people passing in and out at all times; and when 
the weather grew warm he would swell out his 
breast and coo mournfully by the hour for our 
pleasure. 
We can, no doubt, learn best by observing the 
behaviour of nestlings and young birds; neverthe- 
less, I find much even in the confirmed habits of 
adults to strengthen me in the belief that fear of 
particular enemies is in nearly all cases—for I will 
net say all—the result of experience and tradition. 
Hawks are the most open, violent, and persistent 
enemies birds have; and it is really wonderful to 
see how well the persecuted kinds appear to know 
the power for mischief possessed by different rap- 
torial species, and how exactly the amount of alarm 
exhibited is in proportion to the extent of the danger 
to be apprehended. Some raptors never attack 
birds, others only occasionally ; still others prey only 
on the young and feeble; and, speaking of La Plata 
district, where I have observed hawks, from the 
milvago chimango—chiefly a carrion-eater—to the 
destructive peregrine falcon, there is a very great 
variety of predatory habits, and all degrees of cou- 
rage to be found; yet all these raptors are treated 
differently by species hable to be preyed on, and 
have just as much respect paid them as their 
strength and daring entitles them to, and no more. 
So much discrimination must seem almost incredible 
to those who are not very familiar with the manners 
of wild birds; I do not.think it could exist if 
the fear shown resulted from instinct or inherited 
habit. There would be no end to the blunders of 
