8 ALASKA FUR-SEAL ROOKERIES, 1910. 



actual number was at least 200, giving a total of 384. As the average 

 life of the male is 13 years, of which 5 are spent as harem master, 

 the decrease annually of the present active list is 276. It is appar- 

 ent therefore that killing in the past has not been too close, and 

 that there is a sufficient reserve at the present time. 



COUNTS OF IDLE AND YOUNG BULLS. 



The following count of idle and young bulls was made at the time 

 the census of harems was taken. It was not possible without causing 

 undue disturbance to enumerate members of the latter class that had 

 hauled out with the bachelors on four important rookeries — Northeast 

 Point, Gorbatch, the Reef, and Tolstoi. 



Counts op Idle and Young Bulls on St. Paul and St. George Islands, 1910. 



Rookery. 



St. Paul Island: 



Gorbatch 



Ardiguen 



Reef 



Kitovi 



Lukanin 



Polovina 



Polovina Cliffs.. 

 Little Polovina. 



Morjovi 



Vostochni 



Zapadni 



Little Zapadni. 

 Zapadni Reef. . . 

 Tolstoi 



Rookery. 



St. Paul Island— Continued. 



Tolstoi Cliffs 



Lagoon 



Total 



St. George Island : 



East 



Zapadni 



Staraya Artel 



North 



Total 



Grand total 



Idle 

 bulls. 



Young 

 bulls. 



BREEDING COWS. 



While there is a steady increase in the number of cows hauling out 

 on any rookery for a month after the middle of June, a seagoing stream 

 soon makes its appearance, consisting of cows en route to the feeding 

 grounds after their pups are born. Hence at the "height of the 

 season," about the middle of July, the number of cows on the beach 

 is no true indication of the total number, nor does it alwaj^s bear a 

 constant ratio to the whole. Under certain circumstances, possibly 

 due to climatic conditions, nearly the full complement may be present 

 at the height of the season, and again in other years not over 30 per 

 cent of the community may be on the rookery. It thus becomes 

 apparent that such counts, of varying character from season to season, 

 must be used with extreme caution, if at all, in estimating the entire 

 number of females on any rookery or the annual decline or increase. 

 As has been pointed out by others, we may arrive at an approximate 

 estimate only by a count of the pups, and under that heading an 

 attempt has been made to show that even here we must use the results 

 with the greatest care in making a census of the herd. 



