34 SEAL LIFE ON THE PRIBILOF ISLANDS. 



NUMBER OF BREEDING FEMALES ON THE ISLANDS. 



Upon the letuvii of the Albatross to tlie Piibilof Islands on July 9, 

 1895, a general examination of the rookeries was made. Some of the 

 narrower breeding grounds were so thiidy covered with seals that it 

 seemed quite possible to count then). Accordingly, Mr. True and I 

 began on Ketavie rookery and on the 9th and 10th succeeded in taking 

 a satisfactory census. The harems seemed full and well defined, no 

 coalescing having begun, and they were therefore counted sei)arately. 

 This work was continued with Lagoon rookery and portions of Tolstoi, 

 Lukannon, and Keef rookeries, where female seals weie counted as fol- 

 lows: Ketavie, 2.1'18; Lukannon, 1,940; Lagoon, 1,210; Tolstoi, 1,539; 

 Keef, 506. The whole number counted was 7,471>. 



Narrow places limited to the beach slope, like Lagoon rookery, were 

 not difHcult to count from a boat when the sea was smooth, while no 

 trouble was encountered in doing the same with thin rookeries that 

 could be viewed from low cliffs. The value of the data secured can not 

 be overestimated, it being the first time that rookeries were found suf- 

 ficiently reduced in the number of breeding females to admit of their 

 numbers being determined with any degree of precision. Although 

 these rookeries nniy not have quite reached their breeding height, they 

 were so near to it that the corrections to be applied are unimportant. 

 With a very fair set of figures for the extensive area thus examined, we 

 are able to form a more accurate estimate of the number of breeding 

 females on the Pribilof Islands than ever before. Adopting the scale 

 of the rookery charts prepared by Mr. J. Stanley-Brown (204 feet to 1 

 inch) we find the 7,479 seals counted to be distributed over 7.05 acres, 

 making 1,001 seals to the acre. The remaining area occupied by seals 

 has been computed at 54.47 acres, as based upon the rookery ground 

 delineated on the charts for 1895. The result is a total of 05,239 breed- 

 ing females for all the rookeries of the two islands. Some corrections 

 might be ajtplied for certain tracts on Keef, Tolstoi, and Northeast Point 

 rookeries, where the seals always lie more or less massed, but I can not 

 admit that there were between July 10 and 15 more than 75,000 breed- 

 ing females present upon the islands. There is also a correction to be 

 applied for a moderate number of females not on the rookeries at the 

 time the breeding females were being counted. As the season was 

 backward, and the females later than usual in arriving, their appearance 

 was made en masse, so it is altogether ])robable that the number of 

 absentees was not important. 



From the 10th to the 15th of July the rookeries were filled with 

 females that had just brought forth their young. They had not notice- 

 ably begun going to sea to feed, and at no other time were so many 

 coming in heat. It is altogether unlikely that any very important 

 number of females could have been away from the rookeries at a time 

 when the females were still in excess of young. Mr. True found the 

 percentage of young to be 62 on July 9, while on July 20 the young 

 were everywhere in excess of females. Later in the season 50 per cent, 

 at least, of the females were customarily absent from the rookeries. 



