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ORNITHOLOGY. 



NO. X. 



Longevity op Birds. The term of life varies greatly in birds 

 and does not seem to bear the same proportion to the time of ac- 

 quiring their growth, as has been remarked with regard to quadru- 

 ])eds. Most birds acquire their full dimensions in a few months, 

 and are capable of propagation the first summer after they are 

 hatched. In proportion to the size of their bodies, they possess, 

 more vitality, and live longer than either man or quadrupeds. It 

 is no very easy task to ascertain the ages of birds; nevertheless, 

 we have, on unquestionable authority, instances of great longevity 

 in many of them — particularly geese, swans, ravens and eagles; 

 among which, eagles have been know^n to attain the age of sixty, 

 seventy, eighty or even a hundred years. The following scale 

 has been given by Linnaeus, BufFon, and other celebrated natu- 

 ralists. 



An eagle will live 100 years. 



A raven " " 100 " 



A goose " " 70 " 



A pai-tridge " " 25 " 



A turtle dove " 25 " 



A peacock " " 25 " 



A pigeon from 10 to 20 '■ 



Linnets, goldfinches, canary birds, and others, in a state of 

 captivity, have been known to live many years. The longevity 

 of birds has been imputed to the texture of their bones, whereas, 

 on the contrary, the hardness and solidity of bones have been as- 

 signed as the general cause of death in other animals. Those of 

 birds being lighter, and more porous in their conformation, pre- 

 sent fewer obstacles to the vital powers. Hence, it has been as- 

 sumed that the less solid the bones are, the more distant will be 

 the period of dissolution. 



Moulting of Birds. From the great longevity of birds, it 

 has been inferred that they are subject to a few diseases only; 

 their annual moulting is thought to be the only one to which they 

 are universally liable. As quadrupeds cast their hair, so all birds 

 every year obtain anew covering of feathers; this is what is term- 

 ed moulting. During its continuance, they always appear sickly 

 and disordered; the boldest lose their courage; none produce 

 young, and many die under the visitation. No feeding can main- 

 tain their strength, or preserve their powers of reproduction. 

 The nourishment which formerly went to the production of the 

 young, is now concuined and absorbed in administering a supply 

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