that his mate shall admire him and when this coat comes he
sings his very best and--"

"Stop and take breath, my boy," laughed the Doctor; "there is plenty of
time. Why do we think that the male has the gayest feathers--do you
remember that also?"

"No, I've forgotten," said Nat.

"I remember," cried Rap; "it is to please the female and because she
sits so much on the nest that if her feathers were as bright as the
male's her enemies would see her quicker, and when the little birds
hatch out they are mostly in plain colors too, like their mother."

"Oh, I remember that now," said Nat. "And after the young are hatched
and the old birds need new coats, they keep rather still while they shed
their feathers, because they feel weak and can't fly well."

"Then when the new feathers come they are sometimes quite different from
the old ones, and seldom quite so bright--why is this, Nat?" asked the
Doctor. But Nat could not think, and Rap answered: "Because in the
autumn when they make the long journeys the leaves are falling from the
trees, and if they were very bright the cannibal birds would see them
too quickly." "Have I told you about the Bluebird, and how, though he
only sheds his feathers once a year, yet his winter coat is rusty and
not bright clear blue as it is in spring?"

"I think not," answered Nat.

"Well, the outside edges of its feathers are blue, but a little deeper
in the feather is brownish. So when they have worn the same feathers
many months, and rubbed in and out of their little houses and bathed a
great deal and cleaned their feathers off every day in the dust, as
birds always do, the blue ends wear off and the rusty parts show. It is
quite worth while to tell little people things when they have the
patience to listen and the interest to remember."

"Yes, uncle, but it's the way you tell us about birds that makes us
remember. You talk as if they were real people."

"Oh, oh, Nat!" laughed the Doctor, "if you flatter me so I shall have to
hide my head in a bush like an Ostrich. Birds _are_ people, though of
another race from ours, and I am happy if I can make you think so. Ah!
we must be near a Redwing's nest--what a commotion the colony is
making!"

"Colony? I thought a colony was a lot of people who went off into a
strange wild land and made a new home," said Nat.

"That is one meaning of the word, but another one is when a number of
people of the same race or trade live close to each other.