"It is very much the same thing," said the Doctor, "only we don't call
it moulting when people lose their hair. But there is this difference.
Birds wear out their feathers much faster than we do our hair, and need
a new suit at least once a year, sometimes oftener. All young birds get
their first new clothes when the down is worn out. Old birds generally
moult as soon as they have reared their broods, which in this country is
late in summer or early in the fall. Many also moult again the following
spring, when they put on their wedding dress; and one of the curious
things about this change of plumage is, that the new feathers often come
out quite unlike those that were cast off. So a bird may differ much in
appearance at different seasons and ages--in fact, most birds do. The
male also differs in many cases from the female, being more handsomely
dressed than his mate."

"I don't think that's fair," said Dodo. "I shouldn't like Nat to have
nicer clothes than I wear."

"But it is best for Bird People," replied the Doctor, "that the mother
bird, who has to keep house and tend to the little ones, should not be
too conspicuous. She is best protected from enemies when her colors are
plain, and especially when they match the foliage in which she sits on
her nest. If her mate has only himself to look out for, it does not so
much matter how bright his plumage may be. The colors of some birds are
so exactly like their surroundings, that you might look long before you
could find the sober, quiet female, whose mate is flashing his gay
plumage and singing his finest song, perhaps for the very purpose of
attracting your attention away from his home. 'Protective coloration,'
is what the Wise Men call it."