STRUCTURE OF BIRDS. 91 



its nest, which he inspects, and takes note of its migrations or 

 local shiftings. The food can be detected with accuracy only 

 by opening the crop and gizzard ; and the changes in the 

 colour of the plumage can be ascertained only by procuring 

 individuals at different seasons. In attending to these and 

 other particulars, one necessarily requires much enthusiasm, 

 and consumes much time. Indeed the task of writing the 

 history of a bird not of common occurrence, such as the Golden 

 Eagle, the Raven, or the Rock Pigeon, is by no means so easy 

 as might be imagined, unless to those who merely compose it 

 from the accounts given by original observers, whom they fre- 

 quently greatly excel in popular estimation, although in very 

 many instances they cannot so much as have seen the objects 

 of which they so confidently write. When the student has 

 rendered himself familiar with a few species, his pursuits daily 

 become more interesting ; and if he at the same time compare 

 his notes with the descriptions given by authors, he will find 

 additional pleasure in observing the particulars in which there 

 is a mutual agreement, and perhaps in occasionally detecting 

 errors in his own or their statements. But at what precise 

 period he becomes an ornithologist, I cannot venture to affirm : 

 whether the first day on which he brings home a Sparrow or a 

 ChaflSnch, or after he has studied an hundred birds, and read 

 the works of half as many authors. 



Notwithstanding the impediments presented by the necessary 

 restrictions preventing persons carrying guns from strolling 

 over the country, there is scarcely any district in Britain that 

 does not present a good field for ornithological research. The 

 uncultivated moors, the craggy summits of the mountains, the 

 wooded glens, the birch and pine forests of the north, the plan- 

 tations and parks of the south, the cultivated fields, the pastures 

 and downs, the sandy beaches, the rocky shores, and the 

 islands of the sea, have all their peculiar species, whose history 

 can be satisfactorily traced only in connection with the physi- 

 cal geography of the districts or tracts in which they reside. 

 For this reason, some knowledge of geology and botany, will 

 always be useful to the ornithologist. The subject of the dis- 

 tribution of birds, even in our own island, small as its extent 



