XXII. BIRDS 



Chordata (continued) 



Class V. — Aves (avis, bird) 



As a class, the birds are very uniform in their essential 

 characteristics. There is probably not a bird in existence 

 that would not be recognized as such on sight. The birds of 

 the world have been grouped into nineteen different 

 orders, seventeen of which are represented in North America. 

 They are widely distributed and are of very great service to 

 man, although their usefulness is poorly understood and 

 but little appreciated. Notwithstanding the fact that all 

 birds possess feathers, they exhibit a considerable variety 

 of form and habits. Some are flightless and run upon land; 

 some are flightless and live almost entirely in or upon the 

 water; some have very great powers of flight and spend 

 their lives flying over the sea, while others with equally 

 strong wings soar high in the air over land. Some fish for 

 a living, some come forth at night to kill, some scratch for 

 their food, while others live upon seeds and various vege- 

 table products. The study of birds with a field glass and 

 camera, not with a gun, is one of the most interesting and 

 enlightening lines of natural history work. 



Example of the Class— the Engwsh Sparrow 



Origin and distribution. —This sparrow was introduced 

 into America from England about 1850 and for this reason 



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