FUR-SEAL CENSUS, PRIBILOF ISLANDS, 1919. 



109 



As the number of bulls is reduced in the herd the counting of pups 

 Avill become easier and the work can be undertaken somewhat earHer. 

 If the force of men recommended is supphed in 1920 doubtless some 

 of the larger rookeries can be counted again. But unless a thoroughly 

 accurate and satisfactory count of harems can be made on a rookery 

 the comit of pups is not so valuable as it otherwise would be. 



PUPS. 



Distribution of Pups in 1919. 



a Based on estimated average harem. 



The number of dead pups was ascertained on each rookery counted 

 at the time the count was made. On those rookeries on which the 

 cows and pups were estimated the number of dead was computed 

 from the percentage of dead used in the 1918 report. The small 

 increase in the average harem, especially on St. George, should have 

 reduced the percentage of dead pups to a slight extent. On St. Paul, 

 conditions were so little changed in this respect, however, that the 

 difference would not overbalance variations due to the laws of 

 chance. Therefore imtil average harems become as large as they 

 have been in some former year (as 1916 for instance) when the death 

 rate was determined for all of the rookeries it seems best to make no 

 change in the percentages. The rookeries which were counted in 

 1919 gave no data upon which to base a reduction. In fact there 

 was in some cases evidence of a slight increase in the number of dead 

 pups. 



