PREFACE. 



THE peculiar geographical position of the British 

 Isles renders them the resort, either permanent or 

 temporary, of a large number of Birds : Wnongst 

 which are many periodical visitors both from 

 high latitudes, driven southwards in winter by the 

 severity of the cold ; and from Africa, whence they 

 fly northwards at the opposite season, in order to 

 avoid the intense heat of an intertropical summer. 

 Besides these periodic sojourners, many species, which 

 are properly resident on the European Continent, 

 occasionally cross the Channel, and make their ap- 

 pearance amongst us as capricious visitors; but, 

 whether led hither by choice, or driven by stress 

 of weather, it is impossible to determine. Instances 

 also occur, but at rare intervals, of solitary specimens, 

 which are undoubtedly of American origin. 



It is possible that some of these may have been 

 transported as captives, and may have escaped from 

 confinement ; or they may have been introduced 

 and intentionally set at liberty. However this may 



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