216 



NORTH AMERICAN FAUNA 74 



Near a sand spit at the southern part of Peter's Island, groups and families of 

 walruses amounting to a total of 100 to 120 head were observed on 5 September. 

 The animals stayed in the water and did not haul out on land, on account of the 

 presence on the spit of three polar bears. Apparently, the animals had lain on the 

 shore but were chased into the water by the bears. 



In the course of the historic exploration and charting of the Northern Sea 

 Route in 1910 to 1915, Starokadomskii (1976) several times sighted walruses and 

 polar bears together on islands in the Laptev and East Siberian seas in summer. 

 On one such occasion, on the newly discovered Vil'kitskii Island, he found the 

 dried-up skin of a small walrus that apparently had been dragged there and 

 eaten by a bear. 



In July 1976, G. C. Ray and co-workers (personal communication) saw 

 several polar bears in association with walruses, along the ice front of the eastern 

 Chukchi Sea. One of the bears was feeding on the remains of a walrus calf, 

 which had been almost completely consumed except for its skin. In June 1978, 

 L. M. Shults (personal communication) sighted a polar bear creeping up on a 

 herd of walruses north of St. Lawrence Island. 



These accounts at least confirm that polars bears stalk and chase living 

 walruses, and that they occasionally make contact with them. In other reports, 

 the bears and walruses seemed to disregard each other entirely (Nansen 1926 in 

 Mohr 1952; Brooks 1954; Nyholm 1975); in some instances, the bears rather than 

 the walruses seemed to have been the victims (Freuchen 1935:109; Pedersen 

 1962:51). From all reports and opinions, it is apparent that contact between 

 polar bears and walruses occurs mainly in summer, and that only the younger 

 walruses are really vulnerable to predation. The bears probably are no match for 

 healthy adults in direct combat. 



Killer Whale 



The killer whale resides in considerable numbers in the Bering and Chukchi 

 seas (Tomilin 1957). Though it seldom is seen in ice-covered areas such as those 

 inhabited by most of the walruses in winter, there is ample opportunity for inter- 

 action in spring, summer, and autumn, when the walruses mostly inhabit the 

 edge or the open pack or occur in ice-free waters (Tomilin 1957; Fay 1974). 



Belopol'skii (1939) regarded this whale as the walrus' principal natural 

 predator. Scammon (1874:180), Zenkovich (1938a), and Nikulin (1941) claimed 

 that its predation is directed mainly at the youngest animals, especially the 

 calves. According to Scammon (1874), the calves, when not otherwise available, 

 are dislodged from the mother's back by ramming her from below. Two 

 eyewitness accounts of killer whales attacking walrus herds in the Gulf of Anadyr 

 were reported by Zenkovich (1938^7:110): 



The killer whales acted like wolves on land: they surrounded the group of 

 walruses on all sides; then, 6 or 7 on each flank formed straight lines, each whale 

 just behind the head of the next; 5 approached the walruses from the front and 10 

 came in from behind. Then one of the whales which had come in from the rear 

 burst into the herd and divided it, whereupon the others moved into that location, 

 and the water there boiled as in a cauldron. 



In September 1936, I observed a similar systematic slaughter from an SH-2 

 aircraft, in which I was flying over the Anadyr Gulf in search of whales. About 60 

 to 70 walruses, headed in the direction of Cape Preobrazhenie, were surrounded 



