THE BIRDS Oi' COKNWAliL. 183 



breeding contingent. Some birds seem constant to one particular 

 fiy-line, but otliers enter tbe county by more than one route, and 

 are evidently influenced in their choice by the prevailing winds 

 and the nature of the season. 



The routes pursued by the emigrant birds are not so well 

 understood. Many species return more or less closely along the 

 same fiy-line as they followed in coming. Some adojDt consider- 

 able variations ; others return by totally different routes. Flocks 

 of Swifts and Starlings seem to go much further west in autumn 

 than they do in spring, and so, as D' Urban and Matliew suggest, 

 by getting a good " offing" from the land before keeping away 

 to the south, they avoid the mountain ranges of Spain and 

 Portugal, and "fetch" the Azores, Madeira, and the north-west 

 coast of Africa. 



As my object in introducing this outline sketch of the 

 migration of county birds is to stimulate enquiry by directing 

 observation into definite channels, I reserve for another time 

 all detailed examination of the migration of individual species, 

 and also of those variable winter movements that depend 

 on the severity of the weather. At the same time I appeal to 

 Bird-lovers throughout the county to co-operate in the work that 

 has made such satisfactory progress during the last three years. 

 To arrive at a true knowledge of the facts simultaneous observa- 

 tions are necessary' all through the county, and in spite of 

 gratifying increase the number of watchers is not nearly su.fficient, 

 and many of the districts are still without an observer. 



To aid the student a little in picturing the migratory move- 

 ments, I have indicated on the accompanying list the distribution 

 of the breeding area in western or middle Europe for the so-called 

 residents, but have not as a rule attempted to trace its eastward 

 limits. The summer range in Europe, at least, of our winter 

 visitors and the area or southern limit of the winter quarters of 

 our summer migrants I have also given, though it must not be 

 concluded that the individual birds that leave us in autumn 

 descend to the extreme south of their winter distribution. This, 

 as a rule, would only be the case when Cornwall was at or near 

 the northern boundary of the breeding area, for it seems that 

 only the most northerly breeding birds of any given species 

 winter at or 21 ear the southern limit. The summer and winter 



