CLASS AVES 



613 



New World, have been appropriately called feathered gems, or, 

 according to Audubon, " glittering fragments of the rainbow." 

 Only seventeen of the five hundred or more species occur in the 

 United States, and only one, the ruby-throated humming-bird, 

 Trochilus colubris (Fig. 502), is found east of the Mississippi 

 River. This beautiful little bird is only three and three-quarters 

 inches in length. It hovers before flowers, from which it obtains 

 nectar, small insects, and 

 spiders. The nest, which 

 is saddled on the limb of 

 a tree, is made of plant 

 down and so covered with 

 lichens as to resemble its 

 surroundings very closely. 

 Two tiny white eggs are 

 laid. The young are fed 

 by regurgitation. 



The swifts (Micro- 

 podid£:) resemble the 

 swallows superficially, but 

 their anatomy shows that 

 there is no real resem- 

 blance between the two 

 groups. Of the one hun- 

 dred species and sub- 

 species of swifts, four are 

 inhabitants of North America, and one, the chimney-swift 

 (Chatura pelagica), breeds commonly in eastern North America. 

 This species formerly made its nest in hollow trees, but now 

 usually frequents chimneys. When in the open air it is 

 always on the wing, catching insects or gathering twigs from 

 the dead branches of trees for its nest. The twigs are glued 

 together with saliva and firmly fastened to the inside of the 

 chimney, forming a cup-shaped nest. Certain species of swifts 

 inhabiting China make nests entirely of a secretion from the 



Fig. 502. — Ruby-throated humming-bird, 

 Trochilus colubris. (From Davenport, after 

 Fuertes.) ' 



