CHAPTER XXVII 



BIKDS IN RELATION TO HORTICULTURE 



The importance of the study of birds in 

 connection with school gardens is due to their de- 

 pendence upon plants for food. 



As the digestion, breathing, and blood-circu- 

 lation of birds are extremely rapid, there is an 

 enormous expenditure of vital energy, and great 

 bodily exhaustion ; consequently, a vast quantity 

 of food is required to repair the waste. The food 

 must be nourishing and concentrated, hence it con- 

 sists largely of insects, fruit, and seeds, which 

 afford the greatest possible amount of nutriment. 



Birds are divided into orders and families, 

 based upon their skeletal, muscular, and visceral 

 characteristics; into genera by external charac- 

 teristics — bill, feet, wings, and tail; into species 

 and subspecies by color and size. The muscular 

 and visceral characteristics are related to the 

 kind of food; the bill, feet, wings, and tail to 

 the mamner of getting it ; the color and size are 

 for protection and attraction. 



Birds are divided into seventeen orders. 

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