110 THE FUR SEALS OF THE PRIKILOF ISLANDS. 



SUMMARY OF PERCENTAGES. 



From these figures we may draw the following summary of percentages: 



Percentages of decline as shown by counts. 



The results in this limited count of harems are not so striking as in the completed 

 count of harems for each season on all the rookeries. These were 4,932 in 1896 and 

 4,418 in 1897, a decrease of 10.41 per cent. 



DECREASE IN THE AVERAGE SIZE OF HAREMS. 



In connection with this marked decline in the number of breeding families it may 

 be noted that on Kitovi rookery, which we have taken as typical of rookery conditions 

 in general, there is also a marked decrease in the size of the individual harem. In 

 1896 the apparent size of harem, as shown by a count of cows, was 17.3; in 1897 it was 

 13.6, a decrease of 21 per cent. As this rookery was counted on exactly the same date 

 and under like conditions these figures may properly be compared and are significant. 



THE COUNT OF COWS. 



The count of cows, which shows a decrease of 28.34 per cent, is less certain but 

 is still significant. Owing to their constant coming and going, the number of females 

 on the rookeries in the height of the season varies greatly from day to day. This will 

 be clearly seen by reference to the daily counts of cows on Lukaniu and Kitovi rookeries 

 during the season of 1897, which will be found in Appendix I. The count of cows 

 and pups, as recorded above in the case of Zapadni Reef and Polovina cliffs, where the 

 latter were three times as numerous as the cows, furnishes a good illustration. At 

 the same time, while the decrease shown by the comparative counts of cows can not be 

 taken at its full value, the fact of large decline thus shown can not be ignored. 



THE COUNT OF PUPS AN ABSOLUTE MEASURE. 



The final and absolute measure of decline, however, is to be found in the counts 

 of pups. As we have seen, the number of harems fluctuates. The cows come and go, 

 and throughout the breeding season the rookeries are undergoing constant change. 

 With the pups this is not the case. They are fixed upon the rookery to which they 

 belong at least for the first six weeks of their lives. A count of these animals, living 

 and dead, is an exact index to the number of breeding cows which have during the 

 season appeared upon the breeding ground in question. 



