162 THE STORY OF BIRD-LIFE. 



These are able to feed themselves almost at 

 once, and only require the mother to guide them 

 to places where food is procurable, to instruct them 

 what is good to eat, and to keep them warm at 

 night, and protect them from enemies. Without 

 her they would roam about and soon get lost. 



In almost every case, so soon as the young are 

 old enough to look after themselves, they are 

 driven away from the neighbourhood of their 

 birthplace to seek homes elsewhere. This is 

 really a wise act. It prevents too many of one 

 species collecting in the same area, and thus 

 obviates two serious evils threatening the welfare 

 of the whole species. The first of these is the 

 danger accruing from too many of one kind 

 feeding in the same area, since the demand for 

 food would soon exceed the supply. The second 

 is the danger of too close interbreeding, which 

 would weaken the race and bring about its 

 inevitable extinction. 



In all birds, except perhaps those of the 

 ostrich tribes, the tip of the upper jaw is armed 

 with a tiny, but very hard, conical boss called 

 the " egg-tooth " ; with this it breaks the wall of 

 its shell and so liberates itself. Soon after the 

 egg-tooth is thrown off. 



For some hours before hatching, the chick can 

 be heard giving vent to that peculiar little cry 

 known as " cheeping." If danger threatens, a 

 warning note is given by the parents, then all is 

 still at once. So that the little stranger begins 

 his education actually before he is born ! 



We have reserved till the last a consideration 

 of the remarkable habits of certain unnatural 



