ion; but
when she leaves her nest to seek her companion, she is enabled by his
brilliant colors the more easily to discover him. The male is diligent
in providing for the wants of the offspring, and hence it is important
that his dress should render him conspicuous. When the young birds
have left the nest, upon seeing the flash of his plumage, they
immediately utter their call, and by this note, which might not
otherwise be sounded at the right moment, he detects them and supplies
them with food. Should a bird of prey suddenly come into their
neighborhood, he overlooks the plainly-dressed mother and off-spring,
and gives chase to the male parent, who not only escapes, but at the
same time diverts the attention of the foe from his defenceless
progeny.

But the birds that build low, either upon the ground or among the
shrubbery, are exposed to a greater number and variety of
enemies. Hence it becomes necessary that the males as well as the
females should have that protection which is afforded by sobriety of
color. Not being made conspicuous by their plumage, they are endowed
with the gift of song, that they may make known their presence to
their mate and their young by their voice. I have often thought that
the song of the bird was designed by Nature for the benefit of the
young, no less than for the entertainment of his mate. The sounds
uttered by birds on account of their young always precede the period
of incubation. The common hen begins to cluck several days before she
begins to sit upon her eggs. In like manner the male singing-bird
commences his song when the pair are making ready to build their
nest. While his mate is sitting, his song reminds her of his presence,
and inspires her with a feeling of security and content, during the
period of her confinement. As soon as the young are hatched, they
begin to learn his voice and grow accustomed to it, and when they fly
from the nest they are prevented by the sound of it from wandering and
getting bewildered. If they happen to fly beyond certain bounds, the
song of the male parent warns them of their distance, and causes them
to turn and draw near the place from which it seems to issue. Thus the
song of the male bird, always uttered within a certain circumference,
of which the nest is the centre, becomes a kind of sentinel voice, to
keep the young birds within prudent limits.

It is not easy to explain why a larger proportion of the birds that
occupy trees should be