CHAPTER 13 



THE AUKS 



IN THE COURSE of cvolution many sea-birds, and groups of sea-birds, 

 have independently become adapted to under-water pursuit. Three 

 groups in particular, the penguins, diving-petrels and auks use their 

 wings as the primary organs of propulsion under the surface. Different 

 as the auks are in appearance from the gulls and waders, the structure 

 of their palate and other anatomical considerations show conclusively 

 that they are closely related to them: this is supported by palaeonto- 

 logical evidence, though the order Laro-Limicolae split into ancestors of 

 the three present families Charadriidae (waders), Laridae (skuas, gulls, 

 terns and skimmers) and Alcidae (auks) as early as the Eocene. The auk 

 that most closely parallels the penguins, the quite flightless razorbill 

 Alca impejinis, the great auk, became extinct on 4 June 1844 (see p. 65). 

 Twenty-one species of the family Alcidae survive ; some people assign 

 them to thirteen genera, though systematists more interested in points 

 of similarity than points of difference, more interested in fundamental 

 rather than easily-modifiable characters, could probably cut them 

 down to a more realistic nine or ten; and might reasonably also 

 take the number of species down to eighteen or nineteen by reducing 

 some to sub-species. 



There seems to be no doubt that the main evolution and adaptive 

 radiation of the auks has taken place in or not far from the Bering 

 Sea. Sixteen of the twenty-one surviving species breed in the north- 

 ern part of the North Pacific, twelve in the Arctic Ocean, and only 

 five in the northern part of the North Atlantic. These five are Alca 

 torda, the razorbill; Uria lomvia^ Briinnich's guillemot; Uria aalge, the 

 guillemot; Cepphus grylle, the tystie or black guillemot; and Fratercula 

 arctica, the puffin. All these breed also in the Arctic Ocean, and two of 

 them (the guillemots) also in the North Pacific; moreover the tystie and 

 puffin have replacement-species (which in the case ol the tystie is con- 

 sidered here to be of only subspecies level) in the North Pacific. The razor- 



