270 



SEA-BIRDS 



Fig. 49 

 Breeding distribution of the razorbill, 

 Alca torda. Black lines embrace probable 

 extent of breeding-range; black dots 

 represent some breeding-places; there 

 are many others in Britain and Eire 



length, plus striking range ot 

 the bill) as the gannet, they 

 would not be able to breed 

 successfully in their familiar 

 dense colonies on narrow 

 ledges. They manage to do so 

 often tolerating less than one 

 body's width between sitting 

 birds, although unmated 

 birds do not usually stand to- 

 gether with their wings or 

 "shoulders" actually touch- 

 ing. The first massing of 

 the guillemots on certain 

 favourite cliffs and the 

 tops of isolated stacks takes 

 place in England, Wales and Ireland in December, and, in 

 Scotland and farther north, in January. In South Wales there is 

 a belief among fishermen that the "eligugs" (guillemots) return "in 

 time for Christmas." These early visits are few and irregular; they 

 take place at dawn and last only for three or four hours. They may take 

 place on two or three succeeding days, and almost always during 

 fairly calm weather. In order to be successful the individual must 

 early locate, claim and retain breeding territory — where a species 

 is so congested in dense colonies that not a square foot of the coveted 

 ground is unoccupied at the height of the breeding season. Neverthe- 

 less at many breeding sites, certain ledges (which may have been used 

 by breeding guillemots in other years) which appear perfectly suited 

 to the successful breeding of guillemots, may not be used at all, the 

 colony continuing to crowd just as densely upon the occupied ledges; 

 in this species slum conditions are a preferred habit rather than an 

 absolute necessity. But crowded conditions may provide social stimu- 

 lation which leads to more successful breeding (Darling, 1938). We 

 have described how guillemots find this stimulation as well in contact 

 with other sea-birds (p. 173): as when razorbills share the same ledges 

 and where guillemots nest in the narrow "neutral" zones between 

 the pedestal-nests of gannets (e.g. Grassholm, Alderney). 



The razorbill, less colonial than the guillemot, returns later in 

 spring. In large colonies it may come to land at the end of January 

 in its southernmost breeding grounds, but main arrivals occur towards 



