20 INTRODUCTION. 



more easily understood than expressed. It would be very 

 difficult to find names for all the curves that are found in the 

 outlines of birds, and still more to point out the differences. 

 It may be observed, however, that the bodies (the necks, 

 heads, and feet vary to suit other purposes) of fast-flying 

 birds are like fast-sailing vessels, compact and round for- 

 wards, and diminished to the hinder extremity. This is so 

 remarkable in the hawk and swallow tribes, that one who has 

 seen any one species on the wing, can know at first sight any 

 other of the tribe, whatever may be the species. It is true 

 that there is the style of flying, or the attitude in repose, and 

 also the haunt of the bird, if in a state of nature, but still the 

 form is an essential element in judging. 



The haunts and habits of birds are certainly the best 

 means of distinction ; but the perfect or detailed knowledge 

 of them requires an acquaintance with the bird, which 

 includes the whole of its natural history as a species, and 

 therefore a few of the more remarkable haunts and habits 

 are taken as indices to the rest, or general heads, under 

 which the others may be arranged as they are found out. 



Of haunts, land and water are the most obvious dis- 

 tinctions. Land birds, with few exceptions, can walk and 

 fly, but they cannot swim. Water birds can, in general 

 walk, and fly, and swim, but in many instances they are bad 

 walkers. The . bird is always best fitted for the performance 

 of that kind of motion which it most habitually performs ; 

 and therefore when we have seen in one bird the organization 

 and the haunt, we may, from similar organization in another 

 bird, infer that the haunt is similar ; and the same inference 

 may be made from the organization to the habit. These 

 inferences are, however, merely general 



Birds are also distinguished by the times of their appear- 

 ance. Those which remain in the same countiy all the year 

 round, are resident birds ; those which come in the spring and 



