ECOLOGY AND BIOLOGY OF THE PACIFIC WALRUS 



9 



tend to push the ice away from the southern coast of the island and from the 

 southern parts of the Chukchi and Seward peninsulas. Thus, the leeward areas 

 very often have open water or thin ice, whereas the windward sides usually have 

 densely packed ice with few or no openings. To the east of St. Lawrence Island, 

 the ice is mostly very heavy and closely packed; to the west, it tends to be much 

 lighter and more open throughout the winter. 



Few records of walrus sightings exist for January. That most of those are from 

 the vicinity of St. Lawrence Island does not necessarily imply that the center of 

 the population is there at that time. Up to this writing, there have been no 

 surveys conducted to determine distribution of walruses in January; nearly all of 

 the sightings indicated in Fig. 4 were recorded by observers on shore. 



In most years, walruses migrating southward through Bering Strait reach or 

 pass the latitude of St. Lawrence Island in December, slightly in advance of local 

 development of heavy ice. During six aerial transects in January 1957 to 1968, 

 between Nome and St. Lawrence Island, I saw no walruses north of 64 °N 

 latitude or east of 170°30'W longitude. Belopol'skii (1939) remarked that 

 walruses were absent from the northwestern Chukchi Sea at that time, but that a 

 few occasionally were taken by the local Chukchi and Eskimos in Bering Strait. 

 The Eskimos on Little Diomede Island in Bering Strait also have taken a few 

 walruses in this month in recent years but always have reported very small 

 numbers (<10) of animals present (J. J. Burns, A. C. Heinrich, K. W. Kenyon, 

 personal communication). Solitary animals occasionally overwinter in the 

 Chukchi Sea, near the village of Point Hope (J. J. Burns, personal com- 

 munication), and in the eastern Beaufort Sea, near Banks Island (Stirling 1974). 

 Far to the southeast, there have been reports of a few animals in the vicinity of 

 Nunivak and Nelson islands (R. L. Rausch, R. Tremaine, personal communi- 

 cation) and in outer Bristol Bay (J. J. Burns, personal communication). The 

 largest group was about 200 that remained in the vicinity of Port Moller for 

 2 months in the winter of 1969 Q. E. Hemming, personal communication). 



February (Fig. 5) 



By mid-February, the pack ice extends southward nearly to the southern edge 

 of the continental shelf in the western Bering Sea and to central Bristol Bay in the 

 east. Cold, northerly winds continue to drive it southward. February is the 

 coldest month of the year in the northern Bering Sea and the period of strongest 

 surface winds. Therefore, it is the time of maximal ice generation and highest 

 rate of southward movement of the pack. 



The number of walrus sightings in this month is substantially greater than in 

 January, but still inadequate to provide a detailed view of overall distribution of 

 the population. Nearly all of the sightings at sea were recorded during aerial and 

 shipboard surveys in the last half of the month. These sightings suggest that in 

 most years, most of the animals are west and south of St. Lawrence Island, 

 distributed much as indicated for March (Fig. 6); the remainder is mainly in or 

 near Bristol Bay. 



I saw no walruses north of 64°N or east of 170°40'W in two aerial transects 

 between Nome and St. Lawrence Island. All of the animals that were sighted on 

 those transects were close to the northwestern part of the island. Eskimos at 

 Gambell reported that walruses were abundant in the thinner, more open ice to 



