entrance. Here he would pass several hours every day, taking no notice
of the 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; nevertheless, 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 not 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 raptorial 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 courage to be found; yet all these raptors are treated
differently by species liable 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 such an instinct as that; and
in regions where hawks are extremely abundant most of the birds would bo
in a constant state of trepidation. On the pampas the appearance of the
comparatively harmless chimango excites not the least alarm among small