308 VERTEBRATE ZOOLOGY 



cleft mouth fringed with stiff hairs, used to trap insects as they fly 

 through the air. . Their flight is swift and practically noiseless. Their 

 mournful nocturnal cries sound like " whip-poor-will," " poor-will" 

 "who-are-you," etc. 



Micropodii (hummingbirds and swifts) are the smallest of birds. 

 Of the hummingbirds (Fig. 158, C) much has been written in praise 

 of their beauty. "Glittering fragments of the rainbow," Audobon 

 calls them; while Knowlton characterizes them as "gems of the feath- 

 ered race." Small though they be, they are among the most highly 

 specialized of all birds; and therefore, .of vertebrates. They seldom 

 alight, but feed while upon the wing, hovering over a flower, poised 

 as though resting, but continuously beating the air with vibrant 

 wings, whose speed of wing-stroke rivals that of the insects. Their 

 tiny eggs and nests are objects of intense curiosity among bird-lovers; 

 some of the nests are of the size of a thimble and the tiny eggs are 

 like pearls. Though of miniature size the hummingbirds are pugna- 

 cious and full of courage, a pair of them not hesitating to attack such 

 giant intruders as hawks and large snakes. 



The swifts are less attractive than their relatives, the humming- 

 birds, and are often mistaken for swallows. They have the bill short 

 and broad, and the wide gape of mouth like the goat-suckers. 



The Colii (colies) are a small group of somewhat anomalous birds, 

 that have often been placed in the order of passerine birds, but, on 

 account of apparent affinities with the plantain-eaters, they are placed 

 in the present position. 



The Trogones (trogons) are highly specialized tropical birds of 

 comparatively small size, with long tail, short strong bill, and very 

 elaborate plumage. The quezal (Fig. 158, A) is one of the most 

 wonderfully colored of the trogons, if not of all birds. Its brilliant 

 plumage of gold, metallic greens and blues, and its gracefully drooping, 

 ethereal plumes give it an almost unearthly beauty. 



The Pici (picarian birds) include both familiar and unfamiliar 

 types such as the jacamars and puff-birds, barbets and honey-guides, 

 toucans, woodpeckers and wrynecks. Of these we must be content to 

 examine only the toucans and woodpeckers. The toucans (Fig. 158, B) 

 with the possible exception of the horn-bills, have the most remark- 

 ably specialized bill known. As Stejneger says, " The first thing which 

 strikes the observer, when looking at one of the large Toucans, is 

 the enormous size of the bill. It is not only as long as the bird itself > 



