330 THE PUR SEALS OF THE PltlBILOF ISLANDS. 



POLOVINA ROOKERIES. 



The Polovina rookeries show some decrease from the conditions of last year. The 

 decrease in hauling-ground area is more marked. The space at present occupied is 

 but a fraction of the former area. It is almost impossible to count the harems on the 

 main part of Polovina, but Colonel Murray reports finding 138 harems on the 15th, 

 and, so far as we can judge to-day, this is about right, though at this time the harems 

 are beginning to be demoralized. 



The maximum extension of the breeding area on this rookery is still pretty well 

 defined by the position of the idle bulls. Of these there are nearly enough to fill the 

 old grounds, but the scarcity of females leaves two-fifths of them without harems. 

 This thinning out of cows indicates a falling off' much greater than the mere reduction 

 of rookery space on the map can exhibit, because not only is less space occupied, but 

 this less space is more thinly occupied. 



The rookeries are fullest about July 15. Then each harem has its characteristic 

 form and position. When cows are many and the grounds level, various harems run 

 together in a mass. Bach bull at first tries to control his own cows and round them 

 up; but later on this can not be done, and finally two or three bulls rest on the 

 edge of the mass, holding the cows in common. 



After a while the wandering of the pup attracts the mother away from the 

 harem. Impregnated cows have no further interest in the bull and follow the pups 

 or go into the water, and the harems grow vague in their lines of demarkation. This 

 is more or less true by July 18, when one-fourth, perhaps one-third, of the cows only 

 are ever present. 



The attractiveness of the bulls cuts no figure in building up harems. The bull 

 does no courting, nor does he make any effort to please the cows. The position he 

 holds is, in the first place, the reward of his force and pugnacity; but the size of the 

 harem is determined by the advantage of the position and with reference to the place 

 of landing of the cows. He can not leave this position to secure cows, without being 

 supplanted. He must wait for them to come to him. All bulls seem to be alike to 

 the cows, but the cows like certain places, and the more so if their pups are there. 

 When the pups are podded, the cows scatter about and the rookery spreads. 



As a rookery declines, the masses break up into individual harems, rounded up 

 by the bulls, and the breaks between the harems become larger. This makes a count 

 by space occupied a thing very untrustworthy. On rocky ground, among lava blocks, 

 and gullies, the scattered arrangement is universal, and probably has always been so, 

 as no massed arrangement is possible under the rough cliffs of St. Paul. On Polovina 

 cliffs and Kitovi little harems may be seen stowed away in all sorts of queer corners. 



DEAD PUPS.' 



On the way home three dead pups, not in a condition to be examined, were tbund 

 on the beach approaching Lukanin Rookery, but a very long way distant from the 

 harems. These pups could hardly have wandered there, and were probably dead pups 

 washed over from Lukanin by the high surf, as they seem to have been dead for some 

 time. They do not appear emaciated. 



'This whole subject of the death of pups must be reviewed iu the light of the fuller investiga- 

 tions of 1897. 



