music, but because they are telling us how happy they are!

If birds are in pain or in trouble, their notes are quite different
from when they are singing; while, if they or their little ones are
in danger, they quickly send forth a note of warning. The young birds,
in calling for food, make an entirely different sound, and the answer
of the mother bird is a sweet lullaby. One of the ways birds express
themselves in sign language is by their feathers. If they are sick,
their feathers droop. When they are well and happy, their feathers
seem much brighter.

In the bird family, as in the flower family, each member has a special
work to do. The mother bird and the father bird work together to build
the nest, but while the mother bird lays the eggs and then must sit on
them for a number of days, the father bird must bring her food and water
and sometimes take his turn watching the nest while the mother goes for
a little exercise. The mother bird's body resembles the plant, too, for
it needs fresh air, food and water. Instead of leaves to take in the air
it has lungs, which not only take in the fresh air but also send out the
impure air. Instead of the little rootlets to take in the food and water
from the ground, the bird has a mouth, and as the bird is not fastened
to the ground, but is free to fly or move about, it goes after its food.
Instead of sap, it has blood to carry the food to all parts of the body.

The birds have ovaries just the same as the flowers, and inside each
ovary are a number of little seeds or ovules which by and by will grow
into birdies. It takes quite a while for the ovules to ripen, just as it
took quite a while for the seeds to ripen, and when they are ripe they
must have a nest prepared for them, just as the flowers did. But the
birds are not as helpless as the flowers, and are able to make their own