FUR-SEAL CENSUS, PRIBILOF ISLANDS, 1919. 115 



and five years of fighting will probably wear him out. When they 

 are less numerous and there is but little fighting to be done the breed- 

 ing period is certainly much longer. A 7-year-old bull is sufficiently 

 developed sexually to have a harem, and it is not doubted they will 

 do so when the average harem shall have increased to about 40. 

 Wlien this occurs it will necessitate the assumption of less than 20 

 per cent annual old-age loss of bulls. 



ENEMIES. 



The only enemy of which we can be sure is the killer whale. The 

 voracious attacks of this animal on the fur-seal pups have been too 

 well described to need repeating here, but they would not have to 

 continue long to account for the entire loss. 



The urgent need of combating this animal is easily seen. Out of 

 150,000 animals born in 1919, 75,000 are sure to perish before they 

 are of any value to the herd or to man. At the present value of furs 

 these would be worth over S5, 000,000. Of course all of the enemies 

 could not be eliminated in any one year, but it is quite evident that 

 it would be financially profitable to make a determined start. 



It also is desirable in this connection to point to the paucity of 

 information about the fur seals at sea. The animal is so exceedingly 

 valuable that it is very desirable to have its habits and habitats 

 thoroughly investigated. There may be other enemies just as bad as 

 the killer, but any such conjecture emphasizes our ignorance. 



INTERISLAND MIGRATION OF MALES. 



In 1914 and 1915 it was determined beyond question or doubt that 

 2 and 3 year old males haul out indiscriminately on any hauling 

 ground on either island. This was learned by clip])ing the hair from 

 the heads of branded seals. On St. Paul the right side was clipped 

 and on St. George the left; this made it possible at a later date to 

 identify the animals which had been handled. The same thing had 

 been determined, perhaps less satisfactorily, a great many years before 

 by clipping the ears of pups. 



It was supposed from this that there was indiscriminate mixing 

 among the older classes, and little attention was given the subject 

 until 1919. 



In the commercial operations of 1918-19 it has been noted that only 

 in two or three instancies have branded males of the 1912 series been 

 seen on rookeries other than those upon which they were marked in 

 1912; but they have appeared in respectable numbers on those. 



The absence of large males on the St. George hauling grounds in 

 1919 in t})c numbers which were expected led to a close inquiry into 

 the subject. Constant effort was made to secure a quota which had 

 been tentatively set, but the 6-year-olds and over were not available. 

 Upon my arrival from St. Paul in census study this was particularly 

 noticeable and was borne out in the bull counts and average-harem 

 computations. 



