256 THE BIRDS OF THE BRITISH ISLES. 



speckled with yellowish brown, and the neck, where the feathers 

 are pointed and have light shafts, is lighter than the head and 

 back ; the under parts are more cinnamon-brown. The bill 

 and legs are black, the cere blue-black, the irides dark brown. 

 Length, 22-25 ins. Wing, 16 ins. Tarsus, 2*5 ins. 



Richardson's or Arctic Skua. Siercorarius parasiticus 

 (Linn.). 



The Arctic Skua (Plate 114), is a circumpolar bird, but 

 though it nests in the Arctic in both hemispheres, its range is 

 really more southern than that of two of its congeners, and 

 extends to northern Scotland ; in winter the bird inhabits 

 warmer seas, but though recorded far south is normally a 

 northern species. It nests in colonies in the north of Scotland, 

 the Orkney and Shetland Isles, and some of the Hebrides. On 

 migration it is at times noticed in extraordinary numbers, 

 especially on the east coast, the most extensive movements 

 being after or during stormy weather. Saunders' "compara- 

 tively irregular in the western sea," has been mutilated and 

 enlarged upon in various text-books by naturalists with no 

 experience of the west coast, until the impression appears 

 general that the bird is a mere vagrant. This is quite a 

 mistake ; though usually off shore, the autumnal passage from 

 August to October is regular though less extensive than in the 

 east. Mr. R. W. Jones on one occasion counted forty-two 

 passing the Great Orme in the course of a three hours' watch. 



Richardson's Skua, as some prefer to call it, is dimorphic, 

 having more or less stable dark and light forms which inter- 

 breed. It is, however, a variable bird, and all manner of 

 intermediate forms occur. The dark phase is perhaps the 

 commoner in our seas, and in this the bird resembles a 

 small Great Skua with much more elongated and pointed 

 central tail feathers, projecting in adult birds about . three 



