[14- BRITISH BIRDS, TIIEIil EGGS AND XESTfc. 



with. I have seen it abundantly at Flamborough Head and St. 

 Abb's Head, and in smaller numbers on many parts of the York- 

 shire coast north of Elamborough, as well as in others not distant 

 from St. Abb's. It usually selects for the site of its nest a flat 

 ledge or other rock-surface towards the upper part of the cliff ; 

 but will sometimes build on a low rock or grassy islanfl. The 

 nest is like that of the last species, but even larger, and usually 

 contains three eggs. These so strongly resemble those of the 

 Lesser Black-back as to make it very difficult to distinguish 

 between the one and the other. Mr. Hewitson says the only 

 means of distinction available even to an experienced eye seem to 

 depend on the somewhat greater size of the Herring Gull's egg, 

 ana the larger and more confluent character of the blotches of 

 surface colour. Fiy. 4, plette XII. 



311. GREAT BLACK-BACKED GULL (Lams marinus). 

 Black-back, Cob, Great Black-and-white Gull. By no means 

 a numerous species, and not affecting society as so many of the 

 other Gulls do. It breeds, in some cases, on the Marsh or Salting- 

 spaces met with so abundantly on some of the southern and 

 eastern shores ; but more commonly on rocky parts of the coast. 

 Thus, it breeds very abundantly on the Orkney and Shetland 

 Islands. The nest is made of a large quantity of dry grass 

 simply thrown together. The eggs are three in number, often 

 bearing a great resemblance to those of the two species last 

 named, but usually distinguishable by the larger masses of 

 surface colouring, and by some superiority in size. The Black- 

 back's eggs are much esteemed as articles of food, or for cooking 

 purposes generally. The yolk is very deep and rich-coloured, 

 and the white colourless or transparent. Each female will lay 

 three sets of eggs ; the first two sets being, in some cases, 

 customarily taken, and the last left for her to hatch. 



312. GLAUCOUS GULL (Larusglaucus). 

 Large White-winged Gull, Burgomaster. A Gull equally large 

 with the last, one of which, shot by myself, exceeded six feet 

 from the tip of one wing to that of the other , but one of merely 

 casual occurrence as a British bird. 



313. COMMON SKUA (Lestns catarractes). 

 Skua Gull, Brown Gull, Bonxie. We pass here into a some- 

 what different class of birds. The Skua is as bold and insolent 

 as most of the Gulls are timid and retiring. In many instances 

 these birds do not take the trouble to fish for themselves, but, 

 watching the fishing operations of the Gull, seize their ^ oppor- 

 tunity of assailing a successful fisher, and compel him to disgorge 

 !:is prey. The Common Skua has only a very limited breeding- 



