ones, which, as a rule, begin the meal first--such are their
rules of propriety-already were sitting upon the haystacks of the
neighbourhood and kept watch, while the younger ones were
continuing the meal, surrounded by bands of crows. From this and
like observations, Syevertsoff concluded that the white-tailed
eagles combine for hunting; when they all have risen to a great
height they are enabled, if they are ten, to survey an area of at
least twenty-five miles square; and as soon as any one has
discovered something, he warns the others.(11) Of course, it
might be argued that a simple instinctive cry of the first eagle,
or even its movements, would have had the same effect of bringing
several eagles to the prey. but in this case there is strong
evidence in favour of mutual warning, because the ten eagles came
together before descending towards the prey, and Syevertsoff had
later on several opportunities of ascertaining that the
whitetailed eagles always assemble for devouring a corpse, and
that some of them (the younger ones first) always keep watch
while the others are eating. In fact, the white-tailed eagle--
one of the bravest and best hunters--is a gregarious bird
altogether, and Brehm says that when kept in captivity it very
soon contracts an attachment to its keepers.

Sociability is a common feature with very many other birds of
prey. The Brazilian kite, one of the most "impudent" robbers, is
nevertheless a most sociable bird. Its hunting associations have
been described by Darwin and other naturalists, and it is a fact
that when it has seized upon a prey which is too big, it calls
together five or six friends to carry it away. After a busy day,
when these kites retire for their night-rest to a tree or to the
bushes, they always gather in bands, sometimes coming together