The Eggs of Birds 441 



Arctic-breeding owls, where the nesting must take place at 

 an unreasonably early and cold date in order to give the 

 fledglings time to reach mature strength before the suc- 

 ceeding winter assails them, is that these birds deposit 

 their eggs at intervals of a week or ten days. In this 

 way the mother can envelop in her plumage and keep 

 thoroughly warm one egg and a callow fledgling at a 



FIG. 350. Eggs of Screech Owl. 



time, and is assisted, in respect to the later eggs and 

 fledglings, by the warmth of the older young in the nest. 

 ' The parrots are a wide-spread and numerous tribe, 

 and none of the larger species need lay more than two 

 or three eggs, for they protect them in deep holes in the 

 earth or in trees, and are able to defend them; but some 

 of the smaller parrakeets lay as many as twelve eggs, 

 reflecting the greater dangers with which they have to 



