BICHABD SON'S SKUA 333 



Richardson's Skua. 

 Stercorarius crepidatus. 



Cro^vn dusky ; cheek, neck, and imder parts white tinged with 

 yellow and brown ; rest of the plumage dusky. Length, twenty 

 inches. 



This species breeds in the Outer Hebrides, the Orkneys, and the 

 Shetlands ; it is also said to be a regular breeder in Sutherlandshire. 

 It is a much more numerous species than the great skua, being a 

 regular visitor to the coasts of Scotland in the autumn and spring 

 migrations. In its preying habit it resembles the bonxie, but, unlike 

 that species, is gregarious. It breeds on moors, often at a consider- 

 able distance from the sea, and its nests are widely scattered on the 

 breeding-ground. A sHght hollow in the ground, with a little dry 

 grass for lining, serves as a receptacle for the eggs. Two eggs are 

 laid, and in some cases only one. These vary greatly in shape, 

 some being nearly round, others long and pointed. In ground- 

 colour they vary from russet-brown to pale olive, and are evenly 

 and sparingly spotted with dark brown. 



A curious fact about this species is that there are two forms, 

 one light in colour, the other dark, and that these habitually 

 interbreed; but the young, instead of being intermediate, are, 

 according to Seebohm, light or dark, like one of the parents. 



The pomatorhine skua {S. jpomatorhinus) is an autunm and 

 spring visitor on migration to the seas in the vicinity of the British 

 coasts. In some seasons it occurs in large numbers, but is not very 

 regular in its appearance. Buffon's skua {S. parasiticus) is a rare 

 and irregular visitor on migration to the British coasts. It breeds 

 in the arctic regions, and is circumpolar. 



Stormy PetreL 

 Procellaria pelagica. 



Upper parts black, except the tail-coverts, which are white at 

 their bases ; edges of the wing-coverts slightly edged with white ; 

 nnder parts sooty black ; bill and feet black. Length, six inches. 



