240 



VERTEBRATA 



FIG. 273. Song sparrow. 



is built on the ground but not 

 lined with hair like the song 

 sparrow's, which sometimes is 

 found in a bush. 



Swallows (Hirundinidae). 

 The swallows are character- 

 ized by a forked tail. They 

 are valuable insectivorous 

 birds, seizing their food on 

 the wing. The cliff swallows 

 and barn swallows are the 

 commonest summer species 

 in eastern United States. 

 The bank swallow rears its 

 young in holes excavated to 

 the depth of two feet in a sand bank. 



The Chatterers (Ampelidse). This family is well repre- 

 sented by the cedar bird, famous for its raids on insects. 

 Seven stomachs examined averaged over one hundred 

 canker worms each. 



The Vireos (Vireonidae). The vireos are olivaceous 

 birds, more slender than the English sparrow. The red- 

 eyed and white-eyed are common. The nest is easily recog- 

 nized by the fact that it has the shape of the lower half 

 of a teacup and is constructed in the crotch of a small 

 horizontal limb without any support underneath. During 

 the locust pest in Nebraska four fifths of the food of the 

 red-eyed vireo consisted of these insects. 



Wrens and Mocking Birds (Troglodytidae). The cat- 

 bird and house wren are the best known members of this 

 family. The latter is the most valuable of all birds in 



