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POPULAR SCIENCE MONTHLY. 



There are several reasons why birds require so much food. 

 They are active creatures, being almost constantly in motion 

 some individuals traveling many miles every day. Of all animals^ 

 their blood is the warmest; their temperature is about five de- 



Hairy Woodpecker. 

 Yellow-bellied SArsucKER. 



grees higher than man's. This heat of the body is nicely pro- 

 tected by their covering of down and feathers, but it requires 

 more food to make feathers than to make flesh or hair. 



A tiny bird's body is a highly concentrated bit of nature, 

 which is controlled by an intelligent and active brain that keeps 

 his little system in such constant motion that it must be abun- 



