74 



U.S. BUREAU OF FISHERIES 



Most of the idle bulls wait for cows in the rear of the rookery and 

 usually have small harems before the season is over. The surplus 

 bulls on the hauling grounds wander about continuously, looking 

 for stray cows, but they do not, as a rule, put up any serious fight 

 with harem bulls. 



Nwmbcr of harem and idle hulls, apiArOxbnutc ratio of idle hulls to harem hulls, 



and a/verage harem. I'JS.i 



AVERAGE HAKEM 



The average harem has been determined on a basis of an increase 

 of 8 percent for the cows, and through actual counts or close esti- 

 mates of the bulls. The average harem for the two islands is 38.39, 

 compared with 38.84 in 1931 and 56.77 in 1927. 



The average harem has been constantly decreased during the last 

 few years by leaving a sufficient number of 3-year-old males for 

 breeding requirements. The present average harem may be consid- 

 ered very satisfactory. However, if the cows have been increasing 

 at the same rate as the 3-year-old males, through the leaving of a 

 larger breeding reserve — and there does not seem to be any valid 

 reason to the contrary — then there are actually more cows in the 

 herd than are recorded. In this case, the average harem would be 

 slightly greater than the records indicate. It could not be very much 

 greater, however, as observations show that throughout the entire 

 season there were many surplus bulls roaming around the rookeries 

 and hauling grounds, looking for cows. If there were more cows 

 on hand than could be handled by the harem bulls, these cows would 



