260 



40 



NORTH AMERICAN FAUNA 68 



35 . 



30 . 



25 



<20 



LU 



10 



oQ 5 



Z 



0 



DEC. 

 1958 



JAN. 

 1959 



FEB. MAR. APR. 



MONTH OF DEATH 



( TO 17 MAY ) 



Figure 101.-— Age and sex of sea otters dying in the winter-spring period of 

 1958-59. A — juvenile male; B — juvenile female; C — juvenile, sex unknown; 

 D — adult male; E — adult female; F — adult, sex unknown. 



than a female may be identified. Because of this situation and to 

 avoid a bias in favor of males, only the freshly dead beach speci- 

 mens found in 1959, 1962, and 1963 are listed to give the best 

 available indication of the sex ratio of otters dying during the 

 period of environmental stress (table 56). 



Among 117 juveniles examined on beaches in the three seasons, 

 58 percent were males. In 1963, the sex ratio was 50:50, but in 

 this year the field study was abandoned while the high mortality 

 period was probably still in progress and the results may not be 

 representative. 



That males are not as hardy as females was repeatedly demon- 



Table 56. — Age and sex of otters found freshly dead on Amchitka beaches 



Juvenile Adult 





Males 



Females 



Total 

 num- 

 ber 



Males 



Females 



Total 

 num- 

 ber 





Year 



Num- 

 ber 



Per- 

 cent 



Num- 

 ber 



Per- 

 cent 



Num- 

 ber 



Per- 

 cent 



Num- 

 ber 



Per- 

 cent 



Grand 

 total 



1959 



1962 



1963 



21 

 - 36 

 11 



57 

 62 

 50 



16 

 22 

 11 



43 

 38 

 50 



37 

 58 

 22 



13 

 8 

 1 



68 

 38 

 50 



6 

 13 

 1 



32 

 62 

 50 



19 

 21 

 2 



56 

 79 

 24 



Total- 



68 



58 



49 



42 



117 



22 



52 



20 



48 



42 



159 



