422 



ZOOLOGY. 



to frighten the insects and drive them from cover than in 

 actual excavation. In some species the tapping is a means of 

 attracting the mates. In some cases these birds bury acorns 

 in holes which they have made in the bark of trees, returning 

 for them when other food supplies are low. Somewhat inter- 

 mediate between this group and the next are the humming 

 birds, the chimney swifts and the whippoorwill. 



FIG. 225. 



FIG. 225. Gold-finch (Spintts tristis). U. S. Dept. Agriculture Year-book, 1898. 



The Passer es is a very large order, embracing numerous 

 families of birds, mostly small, with three toes in front and 

 one behind, and adapted to perching. The majority are 

 gifted with some pow r ers of song (O seines). A few, of which 

 the king bird may stand as the type, are known as crying birds 

 (Clamatores) . The Passercs include probably one-half the 

 species of birds. Here are found the sparrows, the thrushes, 

 the wrens, the larks, the swallows, the crows, and their allies 

 (Figs. 223-229). 



