A WINGED CHUM 167 



*'An' what fixes that?" 



"Color, and size," Shan replied. *'In the 

 color, I suppose it's the difference between the 

 Yellow Warbler, which is the color of a canary, 

 and the Cerulean Warbler, which is nearer to a 

 Blue Jay. In size, I suppose the Eaven and the 

 Crows show it best, they're all black, but the Eaven 

 is huge, the Crow middle-sized, and the Fish Crow 

 fairly small." 



''There's a right smart difference there, too," 

 said Bull, puffing steadily at his pipe, "but, when 

 yo ' come to think of it, one does look right like the 

 other. I ain't sure that I can tell the difference 

 between a Eaven a long way off an' a Crow closer 

 by." 



"That leaves the last of the divisions," said 

 Shan, "the 'Sub-Species' Baker wrote of in the let- 

 ter, which, he said, it would be worth our while to 

 hunt for if we ever saw one. And a 'sub-species' 

 is only the difference between birds of the same 

 species which breed and live regularly in different 

 parts of the country. These sub-species, the book 

 says, a chap has got to learn, if he wants to do 

 any real observing, because birds of the same spe- 

 cies may look quite different. Song Sparrows are 

 Song Sparrows all the country over, but there are 



