GREAT SKUA. 253 



Out of rather more than a dozen which are known to have 

 wandered north as vagrants to our islands, single birds only 

 have reached Scotland and Ireland. 



Though the under parts are dark — almost black on the belly — 

 the mature bird in summer is distinct from either of its con- 

 geners, for only the top of the head and nape are black, the 

 chin, cheeks, and throat are white. The mantle and wings are 

 slate, darkest on the shoulders ; the primaries, really black, are 

 frosted with pearl-grey. Pure white under wing-coverts are a 

 good distinctive character, for the bird flies slowly though 

 buoyantly and its wing-beats are deliberate ; when it cants 

 over, the under wing is visible. The bill is blood-red, the legs 

 are vermilion, and the irides dark brown. The food, as in the 

 other marsh terns, consists of insects, small fish, and frogs. 

 Birds have been met with in both spring and autumn, and after 

 the autumn moult the mantle is lighter and the under parts, as 

 well as the forehead, are white ; the black on the head is 

 streaked and spotted with white. The upper parts of young 

 birds are at first mottled with brown, and even when the back 

 is nearly grey the scapulars and tail are still brown towards the 

 tip. The bills and legs of the young are brown. Length, 11 '5 

 ins. Wing, 10 ins. Tarsus, 0*9 in. 



Great Skua. Catharada skua Briinn. 



Skuas differ in form and habits from gulls and terns ; the 

 strongly hooked bill has a horny " cere," and the curved claws 

 are sharp ; the birds look predacious, though they are not 

 regular flesh eaters, and are piratical rather than parasitical, 

 robbing others of their food. Largest, fiercest, and most 

 powerful is the Great Skua (Plate 112), a bird of the North 

 Atlantic, nesting in Iceland, the Faeroes, two large and some 

 small colonies in Shetland, and one at least in Orkney. In 

 autumn these haunts are deserted and the bird becomes pelagic, 



