62 



NORTH AMERICAN FAUNA 74 



Fig. 41. Molting male walruses at Round Island, Bristol Bay, on 24 June. These 

 animals had shed most of their hair, exposing the surface of the skin to view. The deeply 

 pigmented skin of the adolescent male at center contrasts in color and topography with 

 the pale, knobby skin of the adults around him. (Photo by K. W. Kenyon) 



walruses in captivity at lower latitudes. Reventlow (in Mohr 1952) reported that 

 two animals, about 1 year old, in the Copenhagen Zoo began shedding in mid- 

 May and had "beautiful new 'pelts' again" by 25 June. This pattern has been 

 observed also in North American zoological gardens (D. H. Rrown, G. H. 

 Pournelle, and G. C. Ray, personal communication). In eight specimens ranging 

 in age from 1 to 10 years, shedding of the old hair usually was apparent in May 

 (Fig. 42) or at the latest by early June, and the new^ pelage was everywhere 

 emergent, though perhaps not fully developed, by the end of June. 



Molt Process 



The annual molt in the adult walrus seems greatly protracted, relative to that 

 in other sparsely haired pinnipeds, evidently beginning in some individuals as 

 early as March and continuing in others as late as October. The peak of shedding 

 and replacement of hair and of cornified epithelium seems to be in July and 

 August, about the same time as the postnatal molt of the calves. However, the 

 timing of the molt appears to differ between animals in the northern and 

 southern parts of the range, and the loss and regrowth of hair seem more rapid in 

 the latter than in the former. Furthermore, the annual molt in captive walruses 



