CHAPTER 10 



THE SKUAS 



THE GULL-LIKE SKUAS are perhaps the most primitive and certainly 

 the most speciaHsed of the famihes of the Laro-Limicolae, a large 

 order containing the rest of the sea-birds described in this book. 

 Skuas are essentially predators and parasites: at sea they neither dive 

 for food nor seek it by swimming; nor, on the land, do they seek much 

 of their food by searching and probing on foot, as gulls do. Although 

 they swim well, and walk with a waddling gait, they prefer to swoop 

 and grab their food while in flight, piratically. All four species of the 

 family (Stercorariidae) are North Atlantic, indeed, arctic, birds; it 

 seems likely that the suborder Lari, to which both skuas and gulls 

 belong, originated in the north. The largest of the skuas, the bonxie 

 or great skua, Catharacta skua, is one of the few birds with a bipolar 

 distribution. As explained (p. 143), we think it likely that this interest- 

 ing species, or superspecies, originally came from the north but colonised 

 the south; and that the presence of great skuas breeding in the North 

 Atlantic may be a fairly recent development (geologically speaking), 

 a return, so to speak, to the north of the descendants of the ancient 

 stock. These are now, at least subspecifically, distinct from their 

 antarctic and sub-antarctic relations. The great skua's rather narrow 

 distribution in the north is described on p. 144. 



Although gull-like in appearance and habits, skuas are far more 

 oceanic than gulls, travelling considerable distances on migration 

 and remaining at sea throughout the winter, never or rarely roosting 

 on land at that season. The bulky brown form of the bonxie, with its 

 triangular white wing patch, is unmistakable; with its short tail it 

 looks almost clumsy on the wing compared with the graceful long- 

 tailed smaller species — the pomarine, the arctic and the long- tailed. 



These three smaller skuas resemble each other considerably in 

 form, habits and distribution; and much remains to be found out 

 about their fundamental ecology, in which no doubt lies the biological 



