an acquired article of knowledge.

This knowledge is more nicely understood by rooks, who are formed into
societies, and build, as it were, cities over our heads; they evidently
distinguish, that the danger is greater when a man is armed with a gun.
Every one has seen this, who in the spring of the year has walked under a
rookery with a gun in his hand: the inhabitants of the trees rise on their
wings, and scream to the unfledged young to shrink into their nests from
the sight of the enemy. The vulgar observing this circumstance so uniformly
to occur, assert that rooks can smell gun-powder.

The fieldfares, (turdus pilarus) which breed in Norway, and come hither in
the cold season for our winter berries; as they are associated in flocks,
and are in a foreign country, have evident marks of keeping a kind of
watch, to remark and announce the appearance of danger. On approaching a
tree, that is covered with them, they continue fearless till one at the
extremity of the bush rising on his wings gives a loud and peculiar note of
alarm, when they all immediately fly, except one other, who continues till
you approach still nearer, to certify as it were the reality of the danger,
and then he also flies off repeating the note of alarm.

And in the woods about Senegal there is a bird called uett-uett by the
negroes, and squallers by the French, which, as soon as they see a man, set
up a loud scream, and keep flying round him, as if their intent was to warn
other birds, which upon hearing the cry immediately take wing. These birds
are the bane of sportsmen, and frequently put me into a passion, and
obliged me to shoot them, (Adanson's Voyage to Senegal, 78). For the same
intent the lesser birds of our climate seem to fly after a hawk, cuckoo, or
owl, and scream to prevent their companions from being surprised by the
general enemies of themselves, or of their eggs and progeny.

But the lapwing, (charadrius pluvialis Lin.) when her unfledged offspring
run about the marshes, where they were hatched, not only gives the note of
alarm at the approach of men or dogs, that her young may conceal
themselves; but flying and screaming near the adversary, she appears more
felicitous and impatient, as he recedes from her family, and thus
endeavours to mislead him, and frequently succeeds in her design. These
last instances are so apposite to the situation, rather than to the natures
of the creatures, that use them; and are so similar to the act