INTROD UCTION. xxxvii 



The system of classification followed in this work is chiefly 

 in agreement with the List of British Birds compiled by the 

 Committee of the British Ornithological Union in 1885, 

 modified in accordance with Mr. Howard Saunders' Manual 

 (2nd Ed. 1889). 



The most important requirements in the compilation of 

 a local fauna are a careful definition of the true faunistic 

 position occupied by each species, and of its distribution 

 and relative numbers within the area treated of, together 

 with some notice of its migratory movements. To these 

 should be added in the case of the rare species lists of all 

 the occurrences, with dates, localities, authorities, and such 

 other details as are likely to be of service. 



For the purpose of denning the faunistic position of the 

 Birds of Yorkshire, the following terms are employed : 



RESIDENTS } 



SUMMER VISITANTS ..)}' 



WINTER VISITANTS " = REGULAR VISITORS. 



BIRDS OF PASSAGE 



OCCASIONAL OR ACCIDEN- 



i IRREGULAR VISITORS. 

 TAL VISITANTS . . . . J 



RESIDENTS are species which are found in some district 

 or other of the county throughout the year, and therein 

 breed annually. 



SUMMER VISITANTS are species which appear annually in 

 the spring, remain through the summer for the purpose of 

 rearing their young, and afterwards depart in the autumn. 



WINTER VISITANTS are species which appear annually in 

 the autumn, and remain in more or less numbers throughout 

 the winter, departing in the spring for their breeding haunts. 



BIRDS OF PASSAGE are species which are observed in the 

 county only on their annual passage to and from their breeding 

 haunts in spring or autumn, or both. 



OCCASIONAL VISITANTS include the species whose appear- 

 ance in the county is uncertain, but whose occurrence 

 they being resident in, or more or less regular visitants to, 



