OCTOBEK 27, 1911] 



SCIENCE 



569 



this animal upon its natural breeding grounds. 

 Each mature male controls from 1 to 100 

 females, the average number of females in the 

 harems, into which the rookeries are divided 

 being about thirty. The surplus of male seals 

 naturally resulting from the polygamous na- 

 ture of the fur seal is large, and the most of 

 it has always been available for commercial 

 purposes. 



The male seals are thus of two distinct 

 classes: the adults in possession of the breed- 

 ing grounds, and the immature males located 

 entirely away from such grounds. The latter 

 do not acquire the size and courage to fight 

 their way among the large breeding animals 

 until about seven years old, although other- 

 wise mature at the age of four years. 



During the breeding season the mature 

 males are in possession of the harems, where 

 they maintain their positions by sheer fighting 

 ability. Their courage is such that they do 

 not give way even before men armed with 

 heavy clubs, and it is dangerous for men to 

 attempt to enter the rookeries at this time. 

 When the males seize each other with their 

 powerful jaws they frequently tear rents in 

 their thick hides. In a quarrel for the posses- 

 sion of a female, the latter may be frightfully 

 lacerated, and is sometimes killed. Fighting 

 may be seen anywhere in the rookeries and 

 many of the very young seals are trampled to 

 death. 



The destruction of young through the fight- 

 ing of the bulls is of serious extent even when 

 large numbers of surplus males are annually 

 killed for marketable skins. It must have 

 been vastly more serious, prior to the utiliza- 

 tion of seal skins by man. 



It is the belief of naturalists who have 

 studied the fur seal on its native islands that 

 the furious fighting of the males upon the 

 breeding grounds actually constituted nature's 

 check to the unlimited increase of the race. 

 It could have been nothing else, although the 

 worm parasite (Uncinaria) of the sand areas 

 must be considered to some extent in this con- 

 nection. 



Prior to the discovery of the Pribilofs the 

 breeding grounds were undoubtedly overflowed 



at times by such hords of mature males that 

 an important proportion of the young of the 

 year, and many adult females, were destroyed. 



There can be no doubt that the annual re- 

 duction of the male surplus for commercial 

 purposes since the discovery of the islands has 

 greatly lessened the breeding-time turmoil of 

 the rookeries, and that proportionately larger 

 numbers of young survive the perils of in- 

 fancy. 



Now that pelagic sealing, so wasteful of the 

 adult female life, has been suppressed, we may 

 expect an annual expansion of our shrunken 

 breeding grounds. 



The male stock on the islands should be 

 watched with care and its numbers kept within 

 safe bounds. A sudden increase of fighting 

 males in the rookeries at a time when the 

 stock of females has reached the lowest limit 

 in the history of the island would greatly 

 endanger the newly born young. 



Here we may take up a matter of impor- 

 tance to this society. A resolution was intro- 

 duced in the House of Representatives on 

 August 12 to provide for the suspension of all 

 seal killing on the Pribilofs for a period of 

 fifteen years. This resolution may come up 

 for consideration when Congress convenes. 

 Its passage would be unwise in many ways, 

 but chiefly in the danger of a rapid increase 

 in fighting male seals which it would bring 

 about. While a cessation of land killing for a 

 season or two might cause no serious trouble, 

 the fifteen-year period specified is not only too 

 long, but positively dangerous, as the Bureau 

 of Fisheries would be powerless to apply the 

 necessary remedy for the evil of overcrowding 

 by males when it becomes serious. 



The criticism of the administration of the 

 seal islands which called forth the above 

 resolution of August 12, 1911, was made by 

 men who have not been on the islands for 

 twenty years and who can not appreciate the 

 recent detailed investigations. Severe criti- 

 cisms have also been made by men who have 

 not been there at all, and whose opinions upon 

 the subject are of little value. 



Plans have been considered for reducing the 

 loss through the hook-worm Uncinaria. The 



