ECOLOGY AND BIOLOGY OF THE PAGIFIC WALRUS 



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January-February, as implied by the data presented here? Do the females in first 

 estrus ovulate at a different time than the others? What is the normal bulhcow 

 ratio in the mating groups? How many cows does one bull service? Does mating 

 take place in specific localities, year after year? Does mating take place in the 

 water or on the ice? Do the near-term pregnant cows mix with the mating groups 

 or remain segregated from them? What is the nature of the competition between 

 bulls for the estrous cows? Does each bull remain with a specific group of cows; if 

 so, for how long? Do the cows in that group stay together throughout the mating 

 season, or is there free interchange between groups? How old are the bulls that 

 take part in the mating? As the older bulls go out of rut and the younger bulls 

 come in, is there gradual replacement by successively younger breeders? Do the 

 bulls feed during the rut? Is the social organization during the postpartum estrus 

 in summer comparable to that in the winter mating season? 



Information is also needed concerning the time and place of calving and the 

 circumstances during birth and early nurture of the calves. Is the peak of calving 

 really in mid-May? What proportion of calves is born outside the main calving 

 season? Do all births take place on the ice? How soon after birth do the calves 

 enter the water? In what areas does calving take place? Does the cow usually 

 give birth within or apart from the herd? Why do the cows with new calves tend 

 to form large nursery herds, rather than remaining separate or in small groups? 

 Why do they not join non-nursery groups? How strong is the social bond between 

 cow and calf, and what are the circumstances under which it is broken? How 

 important is fosterage to calf survival? Do foster parents feed their adopted 

 calves? How much exchange of calves takes place in the nursery herds? Why do 

 cows with new calves not use the coastal hauling grounds, with the bulls? What 

 is the principal function of the unusually prolonged cow-calf bond? 



Because most of the data presented on reproduction in this report were 

 obtained during periods of suppression and rapid recovery of the population, 

 they may not apply to the population at or near maximum size. How will the 

 rates of ovulation, conception, and birth change as the population approaches 

 the maximum? Will the net productivity decline as a result of reduced reproduc- 

 tive effort, increased prenatal mortality, or lowered survival of the young? Will 

 the increased proportion of old animals in the population result in lowered 

 production through semi-senility? 



As yet little quantitative information is available on the feeding habits of these 

 animals outside the St. Lawrence-Bering Strait area, and most of that was 

 obtained in late April to early June. Practically nothing is known about their 

 feeding in the main wintering areas, very little about it in the summering areas, 

 and nothing during the autumn migration. How important is it to these animals 

 to have available a copious supply of bivalve moUusks? Can they get by with 

 alternate kinds of prey? Do some of their prey contain essential nutrients not 

 found in the rest? Do some prey have optimal nutritive value only in certain 

 seasons? Why do the organisms eaten by females tend to be much smaller than 

 those eaten by males? Is this the rule in all areas, in all seasons? What proportion 

 of the dietary intake by the suckling young is made up of benthic invertebrates by 

 the end of the first year? By 18 months? Do they eat the same kinds of organisms 

 as the adults at that time? If a walrus removes the siphon alone from a clam, can 

 the clam regenerate its siphon? How much digging does a walrus need to do to 



