294 



E. BRUN 



1-10 pairs breeding 



11-100 



101-1000 



A 1001-10.000 



GANNET 



Sula bassana 



11 - 100 pairs breeding 

 101-1000 



Fig. 4. Distribution of the razorbill (Alca torda) in Fig. 5. Distribution of the gannet (Sula bassana) in 

 Norway. Numbers refer to localities listed in Norway. Numbers refer to localities listed in 

 Table 8. Table 10. 



(5918'N, 455'E) and north to Bleik (693'N, 

 1542'E). The total Norwegian population of 

 fulmars in 1971 was estimated at 1,100 pairs. 



Gannet (Sula bassana) 



The gannet (Fig. 5), the most recently estab- 

 lished and least numerous of the cliff-breeding 

 seabirds, has the best-known population 



Table 4. Annual production, m x , of the kitti- 

 wake (Rissa tridactyla) at some North 

 Norwegian coastal localities (m x = num- 

 ber of females produced per female). 



Locality 



Sample size 

 Year (number) 



change. Like the fulmar, it was established in 

 1946 on Runde, and the first individuals were 

 undoubtedly of British origin. During its en- 

 tire breeding history on Runde, and also in 

 two of the three new colonies in northern Nor- 

 way established in the 1960's, the yearly in- 

 crease has far exceeded the intrinsic rate of in- 

 crease (Table 10); for gannets with a 50% 

 breeding success, adult mortality of 6%, and 

 35% survival up to first breeding, the intrin- 

 sic rate of increase is about 2% per year. The 

 Runde and Syltefjord colonies are naturally 

 protected by their inaccessibility, but the 

 colonies at Mosken and Nordmjele, which are 

 on small islets, are both easily accessible. The 

 Nordmjele colony, however, has been effec- 

 tively protected from its start, whereas the 

 Mosken colony has been open to visitors; this 

 difference is probably reflected in their dif- 

 ferent breeding success and annual growth 

 rate (Table 11). The breeding success neces- 

 sary to maintain a stable population with the 





