BIRDS 



81 



in the warmer regions 

 of the South and in the 

 spring months move 

 northward; some of 

 them, like the robin 

 (Fig. 71) and the blue- 

 bird, build their nests, 

 rear their young, and 

 stayall summer in north- 

 ern and middle United 

 States. Such birds are 

 called summer residents. 

 Still other birds rear 

 their young in Canada 

 and even farther north, 

 and come to us only as FIG. 69. Kingbird. 

 winter visitants. This 

 seasonal movement of birds is known as migration. 



(Courtesy of National 

 Audubon Society.) 



Migration is 



/f 





FIG. 70. Tree sparrow. (Courtesy of National Audubon Society.) 

 G 



