XXXIV 



YORKSHIRE VERTEBRATE FAUNA. 



A comparison of the three avifaunas based upon a careful 

 analysis in accordance with the faunistic definitions given on 

 page xi yields the following results : 



RESIDENTS . . . . 

 SUMMER VISITANTS - - 



WINTER VISITANTS- - 

 PERIODICAL VISITANTS- 

 CASUAL VISITANTS - - 

 ACCIDENTAL VISITANTS 



ANNUAL BREEDERS. 



= TOTAL AVIFAUNA. 



This decided superiority of the avifauna of Yorkshire over those 

 of the two maritime districts with which alone it is fair to institute 

 comparisons, is to be accounted for by a combination of advan- 

 tages. In Yorkshire the favourable geographical position of 

 Norfolk is associated with its physical advantages and those of 

 Northumberland and Durham, and when it is further considered 

 that Yorkshire possesses in addition a much greater diversity of 

 surface, soil, and climate than either, there remains little reason 

 for surprise at the numerical excellence of its fauna. The 

 superiority is not merely one of numerical extent. Casual 

 and accidental visitants cannot be regarded as true members 

 of any fauna, and the ornithological richness or poverty of a 

 district can only be gauged by a comparison of the number of 

 its residents and regular visitants, and more especially of that 

 of the species which breed annually. In this respect too as the 

 table shows the superiority of Yorkshire is well-marked, demon- 

 strating still more forcibly the advantages possessed by the county 

 which contains the greatest diversity of surface, a diversity 

 ranging in this case from the low carr lands of the E.S.E. to 

 the mountains of the W.N.W., with a coastline affording both 

 lofty and rugged cliffs and sandy flats, thus presenting every kind 



