THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 



89 



and early summer, in which case they would be 10 to 12 months 

 old at time of death. Young that were born in the fall and winter 

 were small (5 to 10 lb., 2.3 to 4.5 kg.) during the period of stress, 

 and being less a burden to their mothers were cared for during 

 this season. These were the young that survived to augment the 

 population. 



During summer, some dependent juveniles were larger than 

 those that were deserted and died during the season of stress, 

 indicating that they were probably more than a year old. Thus, 

 I believe that the period of dependence of the young is normally 

 at least a year and probably somewhat longer. Young somewhat 

 less than 1 year old and in the 15 to 25 lb. (7 to 11 kg.) group do 

 not usually survive in the wild if premanently separated from their 

 mothers, particularly if separation occurs shortly before or during 

 the season of stress. 



At birth the pup is helpless and remains so for several weeks. 

 When the mother dives for food the pup is left floating on its back 

 at the surface, where it usually sleeps. If the pup awakens while 

 its mother is diving, it may squirm and move its hind flippers 

 about in an uncoordinated way. A very young pup appears unable 

 to roll over onto its belly, which the pup apparently attempts to 

 do by twisting the forward half of its body (fig. 50). 



The ages of pups in the wild are estimated on the assumption 

 that during the first year of life a pup grows at a nearly constant 

 rate from about 5 lb. (2.3 kg.) at birth to about 30 lb. (14 kg.) 

 when mother and young may separate. The sizes of pups are 

 estimated by visually comparing pups in the wild with animals of 

 similar body size that are weighed. On this basis, it is estimated 

 that the pup remains nearly helpless during the first month, al- 

 though it is able to crawl weakly for a meter or so on land (fig. 51) 

 and swim weakly in an uncoordinated fashion. 



SOLICITUDE 



Much has been written of the solicitude of the mother sea otter 

 for her young. Snow (1910, p. 142) noted the reluctance of a 

 mother to abandon her pup. 



For two hours we chased this otter, pursuing her between the rocks. The 

 pup had been killed during the first hour, but she was holding it as firmly 

 as ever, until a shot, striking one of her paws, made her drop it; and in 

 trying to regain it she was once more wounded. Again and again she made the 

 attempt, all the time giving utterance to the most plaintive and sorrowful 

 cries . . . 



After retrieving the pup, which the mother was unable to pick 



