28 BRITAIN'S BIRDS AND THEIR NESTS. 



ORDER, GAVI^ (GULLS, &c.) ; 

 Family, STERCORARIID^ (Skuas). 



THE ARCTIC OR RICHARDSON'S SKUA 



(Stercorarius crepidatus). 

 Plate 9. 



We now come to the Gull order, beginning with the 

 small group of birds known from their cries as Skuas 

 or Skua-Gulls. They are predaceous birds, with strong 

 hooked beaks, and with sharp claws on their webbed 

 feet. Sometimes they prey on small mammals and on 

 young and weakly birds, but to a great extent they 

 obtain their food by piratical means. Besides being 

 strong and well armed, they are swift on the wing, and 

 woe betide the gull which is caught in the open with 

 a fish in its crop. It can only escape by disgorging 

 its prey, upon which the aggressor immediately swoops, 

 as likely as not catching it in mid -air. Even the 

 Terns cannot hope to escape the swift robber. 



There are seven species of Skua in all, four inhabit- 

 ing high northern and three high southern latitudes. 

 The former are all visitors on our coasts, but only two 

 nest in the British Isles, and that only in the very 

 north of Scotland. Of these the Great Skua is the 

 largest and fiercest ; but we must give the Arctic Skua 

 first place owing to its greater abundance. Arctic Skuas 

 inhabiting the more southerly portions of the species' 

 range tend to have the entire plumage of a sooty hue ; 

 but as we proceed northwards a form with lighter under- 

 parts gains the ascendancy. All gradations between the 

 two forms, which breed indiscriminately where they meet. 



