XXvi. INTRODUCTION. 



The term of life varies greatly in birds, and does not seem 

 to bear the same proportion to the time of acquiring their 

 growth, as has been remarked with regard to quadrupeds. 

 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, birds 

 possess more vitality, and live longer, than either man or 

 quadrupeds: notwithstanding the difficulties which arise in 

 ascertaining the ages of birds, there are instances of great 

 longevity in many of them. Geese and Swans have been 

 kno\vn to attain to the age of seventy and upwards ; Ravens 

 are very long-lived birds, they are said sometimes to exceed 

 a century ; Eagles are supposed to arrive at a great age ; 

 Pigeons are known to live more than twenty years; and 

 ^ven Linnets and other small birds have been kept in cages 

 from fifteen to twenty years. 



To the practical ornithologist there arises a considerable 

 gratification in being able to ascertain the distinguishing 

 characters of birds as they appear at a distance, whether at 

 rest, or during their flight; for not only every genus has 

 something peculiar to itself, but each species has its own 

 appropriate marks, by which a judicious observer may dis- 

 criminate almost with certainty. Of these, the various 

 modes of flight (whether seen by day-light, or heard in their 

 passing at night) afford the most certain and obvious means 

 of distinction, and should be noted with the most careful 

 attention. From the bold and lofty flight of the Eagle, to 

 the short and sudden flittings of the Sparrow or the Wren, 

 there is an ample field for the curious investigator of Nature, 

 on which he may dwell with inexpressible delight, tracing 

 the various movements of the feathered nations which every 

 where present themselves to his view. The notes, or, as it 

 may with more propriety be called, the language, of birds, 

 whereby they are enabled to express, in no inconsiderable 

 degree, their various passions, wants, and feelings, must 

 be particularly noticed. By the great power of their 



