14 THE FIRST BOOK OF BIRDS 
way. The blue jay brings food to his mate, so 
that she need not leave the nest at all, and many 
others do so. But the kingbird father simply 
watches the nest to protect 1t while the mother 
goes for food. A redstart gets into the nest 
himself, to keep the eggs warm while his mate is 
gone, and a goldfinch coaxes his mate to go off 
with him for a lunch, leaving nest and eggs to 
take care of themselves. 
Another thing the father birds do is to sing. 
This is the time when we hear so much bird 
song. The singers have little to do but to wait, 
and so they please themselves, and their mates, 
and us too, by singing a great deal. 
When the little birds begin to be cramped, 
and find their cradle too tight, they peck at the 
shell with a sort of tooth that grows on the end 
of the beak, and is called the “ege tooth.” 
This soon breaks the shell, and they come out. 
Then the mother or father carefully picks up 
the pieces of shell, carries them off, and throws 
them away, leaving only the little ones in the 
nest. Perhaps you have found these broken 
shells on the ground sometimes, and could not 
guess how they came there. When the bird- 
lings break out of their prison they do not all 
look the same. Ducks and geese and chickens 
and quails, and other birds who live on the 
