34 



NORTH AMERICAN FAUNA 74 



Table 4. Comparative whole body weights of male and female 

 Pacific walruses." 



Whole body weight (kg) 



Males 



Females 



Age class 



No. 



Range 



Mean 



No. 



Range 



Mean 



Calves, < 1 month 



7 



45.4- 77.1 



65.1 



11 



46.7- 73.5 



61.9 



Calves, about 2 















months 



3 



86.2- 104.3 



95.3 



1 



95.3 





Adults: malas > 14 















years, females >9 















years 



54 



880.0-1,656.0 



1,210.0 



34 



400.0-1,250.0 



832.0 



'Sources: lU. Bukhtiarov, J. J. Burns, F. H. Fay, and K. W. Kenyon (unpublished data). 



0 



6 8 10 12 

 Age (months) 



Fig. 20. Increase in weight of eight Pacific walrus calves that were reared in captivity 

 (D. H. Brown, W. P. Heuschele, G. H. Pournelle, and G. C. Ray, unpublished data). 



Growth in weight after the first year, as estimated conservatively from field 

 weights of dead specimens and measured in a few individuals that were reared in 

 captivity, is about as shown in Fig. 21. Females appear to reach their maximum 

 weight (average, 830 kg) at about 12 to 14 years; males undergo a secondary 

 acceleration in weight increase from about the 10th to the 16th year and reach 

 their maximum weight (average, 1,200 kg) sometime thereafter. In general, 



