18 



NORTH AMERICAN FAUNA 68 



Figure 12. — Adult female sea otter eating the head of a large codfish 

 (Gadus macrocephalus) . Note the two abdominal mammae and that the 

 head and neck are relatively of lighter structure when compared with the 

 male. Also, females float somewhat higher in the water than do males. 

 This is an unusually light-colored animal (albinistic) , but the extremities 

 and eyes were normally pigmented. (KWK 59-13-2) 



other, the females usually take alarm and depart before the 

 males do. 



On several occasions we pursued sea otters in an outboard- 

 powered dory in order to capture them in a dip net. Females 

 attempted to leave the vicinity by making long dives. The relatively 

 fearless males often tried only to avoid the immediate vicinity of 

 the boat. One individual surfaced repeatedly in the same general 

 area. After about an hour of fruitless pursuit, we abandoned the 

 chase and the otter began diving for food near the place we first 

 saw him. 



The difference in color between adult males and females was 

 not quantitatively determined. In general, females appear quite 

 black when their fur is dry and fluffy. Males, in general, appear 

 brownish under the same conditions. Black males and brownish 

 females, however, are seen. Both sexes tend to become white 

 headed with age. Dark-headed individuals, however, were exam- 

 ined which had worn teeth, indicating advanced age. Among a 

 group of 10 captive juvenile otters, the animals having the lightest 

 colored heads were males. In general, this difference tends to 

 prevail also in older animals. 



Examination of the photographs and this discussion of diag- 

 nostic characteristics, indicate that the sex of many otters may 



