BIRDS 



81 



in the warmer regions 

 of the Soutli and in the 

 spring montlis move 

 northward; some of 

 them, Uke the robin 

 (Fig. 71) and the blue- 

 bird, build their nests, 

 rear their young, and 

 stay all 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 

 winter visitants. This 

 seasonal movement of birds is known as migration. Migration is 



Fig. 69. 



- Kingbird. {CourtOHy 

 Audubon Society.) 



of National 



Fig. 70. — Tree sparrow. (Courtesy of National Audubon Society.) 



