Gavice 233 



produce this effect, but the action of the birds seems 

 to be natural, and it is doubtful if they really mean to 

 strike. But they look very terrible, and generally 

 manage to frighten new-comers. When not nesting 

 the Great Skua is a seafaring species, which keeps well 

 out in the ocean and is comparatively seldom observed 

 with ijs except in northern Scotland ; it lives, as others 

 of this group do, on fishes and fowl, and constantly 

 procures the former by forcitog the Gulls to disgorge 

 what they have just caught. Its flight, though heavy, 

 can be easily accelerated with this object ; its note is 

 a harsh cry, supposed to resemble the syllables " skua, 

 skua." The present species is the biggest of our 

 " Parasitic Gulls " or " Gull-teasers," and is termed 

 the Bonxie in Shetland; elsewhere it only breeds in 

 the Faeroes, Iceland, and in Hudson Strait, though 

 closely allied species are found in the southern ocean 

 down to the Antarctic regions. 



Our remaining Skuas belong to a different genus, 

 of which Richardson's or the Arctic Skua {Stercorarius 

 parasiticus) is the only one that breeds in Britain, 

 being there confined to the extreme north of Scotland 

 with its islands, though sufficiently common in Shetland. 

 The Great Skua group have the central tail-feathers only 

 slightly projecting, but all the forms of the second 

 group have them extraordinarily lengthened. The 

 Arctic Skua has two phases of coloration; in one the 

 bird is entirely sooty -brown, in the other it has the lower 

 surface and neck white ; in both a yellowish tinge shews 

 on the cheeks and neck. These phases cannot be called 

 sub-species or local races, for they interbreed with each 

 other, though either may be the commoner at any 

 one locality. Colonies are formed which nest on grassy 



