288 STUDIES IN BIRD-MIGRATION 



number of species which are known to have occurred 

 (including native birds), has reached the extraordinary 

 total of 103, and includes such rarities as the Northern 

 Willow- Warbler, the Siberian Chiffchaff, and others. 



During my short visit, I observed thirteen species of 

 birds of passage, including two, the Lapland Bunting and 

 the Grey Plover, which had not previously been known 

 to occur. 



The lighthouse observations date from 1899 to the 

 present time, and are the source of practically all our 

 knowledge of the Sule Skerry bird-visitors, which, thanks 

 to the valuable co-operation of the light - keepers, is 

 considerable. In this connection the contributions of 

 the late Mr James Tomison, a most painstaking and 

 capable observer, call for special acknowledgment, and 

 form the mainstay of this chapter. Mr Tomison also 

 published in the Annals of Scottish Natural History 

 for 1904, an excellent paper on the birds of this island, 

 a contribution to which I shall have frequent occasion to 

 refer. 



CoRvus coRNix, Hooded Crow. — A few appear at 

 intervals during the spring and autumn. Many, how- 

 ever, visited the island on 2nd March 1901, from which 

 date to 1 1 th April the bird has appeared in the spring, 

 sometimes in company with Rooks. The autumn 

 records, which are few, bear dates from 22nd October to 

 4th November. 



CoRVUs FRUGiLEGUS, Rook. — Is almost annually 

 recorded as a visitor in spring, at dates ranging from 26th 

 February to 28th April ; the birds sometimes appear in 

 large numbers, and in company with Hooded Crows. 

 It has only once been observed in the autumn. 



CoRVUs MONEDULA, Jackdaw. — There are no data 



