ECOLOGY AND BIOLOGY OF THE PAGIFIC WALRUS 



25 



Fig. 18. Visual band image of the Bering-Chukchi region on 21 March 1978, received 

 from the NOAA 2 Weather Satellite, showing the distribution of the seasonal pack ice. 

 Dark areas are open water or thin ice; the whitest areas are the snow-covered continents 

 and islands (outlined). Whitish area at lower left is low clouds. 



eastern Canada consistently have low, rocky shorelines with a steep or shelving 

 subtidal zone (Loughrey 1959; Mansfield 1959). However, the sites utilized in 

 the Bering and Chukchi seas are more diverse, ranging from steep to gentle slopes 

 with beach materials varying from fine sand to massive rock outcrops. Beaches 

 adjacent to extensive shallows exposed at low tide are not used. Use of hauling 

 grounds on shore seems to be very much influenced also by sea state and the 

 presence or absence of floating ice. During storms with strong onshore winds and 

 heavy surf, the hauling grounds usually are abandoned or remain unoccupied 

 (Nikulin 1947; F. H. Fay, unpublished data). Several observers have noted that 

 walruses confronted with the choice of ice or land for a resting place always 

 selected the ice (Chapskii 1936; Tsalkin 1937; Nikulin 1947; Popov 1958; 

 Loughrey 1959; Mansfield 1959). 



The use of ice in preference to land conveys some considerable advantages, 

 foremost of which, in my opinion, are nearness to the food supply and freedom 

 from disturbance when resting (Fay 1974). These mammals, being principally 

 predators on benthic invertebrates, probably require a rather large area in which 

 to feed, for their prey are relatively immobile, of small size relative to the 



