72 BULLETIN OF THE BUREAU OF FISHERIES. 



which shows the most considerable divergence of all, the increase is scarcely noteworthy. 

 In Vostochni a state of affairs was observed which may explain its slight excess. 



In this rookery there has always been a very large area between Hutchinson Hill 

 and the sea covered with a relatively enormous aggregation of harems. At the height 

 of the season and later, this area has upon it a dense population of pups. On its sides 

 are extensive hauling grounds for bachelors, with runways leading to the sea. Pups may 

 stray to the ground occupied by the bachelors, become lost, and eventually die of 

 starvation or of mistreatment from the bachelors, for the latter were often seen mauling 

 pups and even attempting to copulate with them. Since not a few of the dead pups 

 recorded for Vostochni were found well within the hauling grounds, some of them 

 bearing the toothmarks of the bachelors, it is highly probable that they met their deaths 

 in the way indicated and thus Vostochni may have suffered in this respect somewhat 

 more than most of the other rookeries. Large numbers of bachelors close to aggregated 

 harems certainly afford, as just indicated, unfavorable conditions for pups, though as 

 a cause for their death, this condition is not to be compared in the number of victims 

 that it claims with such other causes as starvation, asphyxia neonatorum, etc. 



DEATH OF YOUNG SEALS AT SEA. 



The first year is universally considered as the most fatal in the life of seals, the loss 

 during this period by natural causes, though necessarily unknown, being assumed to be 

 50 per cent. Since the loss from all causes during the first month or so of life, before the 

 animal has learned to swim, is seen to amount to less than 2 per cent, it follows that other 

 and very potent causes must operate. 



During the few weeks following the time the animals have learned to swim, deaths 

 from starvation must continue to form a considerable proportion of the total loss. 

 The young animals now wander farther and farther from the spot where they were bom, 

 and by late August may be found in numbers at a distance of a mile or more from any 

 breeding place. It necessarily follows that the mothers, on returning from feeding, 

 must experience increasing difficulty in finding their offspring, and the conclusion is 

 unavoidable that some are never found and are thus deprived of the natural means 

 of subsistence. Little is known regarding the time when the young seals first learn 

 to shift entirely for themselves. Although they may pick up a small amount of 

 food while paddling about the shores in the earl}' autumn, it is not. likely that they 

 actually learn to fish until they leave with the older seals on their first migration. The 

 search for dead pups in early fall has always resulted in a considerable addition to the 

 number of dead as taken at the time of the regular count. 



While the young pups are still about the islands in autumn many are destroyed 

 by killer whales {Orca gladiator), which are frequently observed singly or in small schools 

 cruising about in front of the rookeries and are known to prey especially on the pups. 

 The following actual records of killer whales observed about St. Paul Island in autumn, 

 selected from a large number of observations taken from the island log by the late Dr. 

 Hahn, indicate to some degree the part played by them in the destruction of young 

 seals. A large school of killers was seen near East Landing on October 21, 1875, and 

 five near the same place on September 21, 1891 ; one seen off Reef Rookery on Decem- 

 ber 2, 1902, was playing havoc with a band of seals; fragments of both cows and pups, 

 the work of killer whales, were found strewn along the beach at Northeast Point on 

 November 6, 1904. In the autumn of 1907 killers were reported on numerous occasions. 



