ECOLOGY AND BIOLOGY OF THE PACIFIC WALRUS 



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by a group of about 15 killer whales. We circled a few times over the place at an 

 altitude of 40 to 50 m and were able to follow the tactics of the predators. Exactly 

 as in the first case, the whales closely surrounded the walruses; then, two high fins 

 appeared in the middle of the herd, which separated into groups of 10 to 12 each; 

 the whales "removed" one of those groups in their own way, apparently tearing 

 apart all of the animals. The remaining walruses again united in a compact group 

 and swam toward shore, but the condemned group vanished in a continuous surf. 



Zenkovich (1938Z?) found remains of young walruses (as well as bearded seals) in 

 two stomachs from adult killer whales taken in the same locality. The whales, a 

 male and female, were from a group of 20 that were chasing walruses when 

 intercepted by the whalers. 



Nikulin (1941:52) observed in Koliuchin Bay that, when killer whales entered 

 the bay, the walruses were disturbed and "threw themselves toward the first ice 

 floe, part of them managing to get onto it, while the others, surrounding the floe, 

 kept close to its edge, trying to remain above the level of the submerged part." He 

 also related the report of a captain of a whaling ship, who observed two killer 

 whales attacking an adult female walrus that was accompanied by three young 

 animals. The young ones "were crawling onto the back of the adult, which kept 

 turning its head toward the orcae, threatening them with its tusks." Pedersen 

 (1962) mentioned a walrus that stabbed a killer whale with its tusks. A killer 

 whale that stranded on the northeastern coast of St. Lawrence Island some years 

 ago was reported to have had part of the tusk from an adult female walrus 

 embedded in its side, just behind the right flipper (J. Otiohuk, personal commu- 

 nication). Brooks (1954) reported an incident in which two Eskimos sighted a 

 killer whale and a walrus near Barrow in July and, upon capturing the walrus, 

 found that it was a lactating female. From the actions of the whale and the 

 absence of the walrus' calf, they concluded that the calf probably had been eaten 

 by the whale. 



The mortality from attacks by killer whales may have a greater impact on the 

 population than the mere removal of a few calves. Belopol'skii (1939) reported 

 that he had "many times . . . observed carcasses of [adult] walruses killed by this 

 whale" and that, in some of those, "all of the bones were found to be broken." 

 Murie (1936) mentioned the finding by O. W. Geist on St. Lawrence Island of 

 walrus carcasses that seemed to have been "mauled by a killer whale," and I was 

 told by the islanders of several more during the period of my work there. For 

 example, V. K. Slwooko reported to me in 1969 that he had been to his camp on 

 the southern coast of the island early in June and had found there on the beach a 

 carcass of a walrus that apparently had died the same day ("very fresh, no bullet 

 hole"). He stated that it seemed externally to be undamaged, except that the 

 flippers had been severely lacerated ("all torn up"). Internally, he found that all 

 of its ribs had been "smashed." Another animal in the same condition but still 

 alive hauled out near another camp about 16 km away, the same day (J. 

 Aningayou, personal communication). 



I examined four walruses that I believe had died as a result of mauling by killer 

 whales. One of these was a calf, no more than a few days old, which was found 

 floating in an area where several killer whales were sighted at the same time. In 

 addition to having lacerations on the hind flippers, this animal had several 

 puncture wounds on its face and several groups of parallel lacerations, 2 to 3 cm 



