98 VERTEBRATES: BIRDS. 



and they vary in size from that of a dove to that of a 

 goose. The Terns have the tail very long and forked. 

 They are generally light below, black, and bluish above. 

 They are of the size of a dove and smaller, some being 

 no larger than a robin. They feed upon small marine 

 animals. 



DIVERS. 



The Great Northern Diver, or Loon, is almost as large 



Fig. 163. Great Northern Diver, or Loon. 



as a goose, black above, beautifully 

 spotted with white, and white be- 

 low. It is exceedingly keen-sighted 

 and wary, and it dives so quickly 

 that, seeing the flash of the gun, it 

 is often under water before the shot 

 reaches it. 



Grebes are ' divers which are 

 smaller than the Loon, and in the 

 spring have the head ornamented 

 with tufts of feathers. When 

 alarmed, they remain beneath the 

 surface of the water, exposing only 



Fig. 1 64. Crested Grebe. , , , . , , 



the bill. 



