410 BIRDS. 



The time required for the development of the 

 young varies in different races ; but it is the same in 

 all birds of the same species. Thus, it is from forty 

 to forty-five days for swans, twenty-five days for 

 ducks, twenty-one days for hens, from twelve to 

 fifteen days for domesticated canaries, and only 

 twelve days for the humming bird. 



Almost all birds construct a nest to receive their 

 eggs and serve as a dwelling for their progeny, 

 which, during the early period of life, are unprovided 

 with feathers, extremely delicate, and incapable of 

 feeding themselves. Generally, there is displayed 

 in these structures an art, an ingenuity, and an ele- 

 gance well calculated to excite our admiration. All 

 the successive generations build nests exactly alike, 

 even under circumstances precluding the possibility of 

 their receiving instruction from their parents. A 

 wonderful instinct guides them, and induces them 

 to take many precautions, the utility of which they 

 cannot be supposed to anticipate or appreciate before 

 hand. 



The classification of the Feathered tribes is founded 

 chiefly upon the modifications that occur in their beak 

 and feet, the instruments whereby they obtain their 

 food. According to the characters thus afforded, 

 they are divided into seven Orders, as in the follow- 

 ing Table: 



