274 DISCOVERY REPORTS 



Before going on to an analysis of the systematic measurements of bodily proportions 

 it will be convenient here to examine the sex ratio and the differences which exist 

 between the two sexes. 



In investigating the proportions between the numbers of existing male and female 

 whales certain difficulties arise which make it impossible to estimate the ratio with 

 accuracy. It is certain that Rorquals of one sex sometimes associate in large herds, 

 and it may be assumed that members of one sex may move to some extent (though 

 perhaps a limited extent) in different places or at different times from members of the 

 other sex. Consequently one sex might actually exist in smaller numbers than the 

 other and yet be caught in greater numbers in some particular locality. 



The ratio of the numbers of each sex which are born could be estimated from the 

 sex ratio of foetuses, but the number of foetal records is hardly great enough for this 

 purpose. Some good material, however, is to be found in the statistics of the catches 

 at various whaling stations, for here there are records of the numbers of each sex taken 

 through a considerable number of seasons and at several different localities, and the 

 number of whales recorded is so large that it might be expected to some extent to 

 swamp any differences due to local movements of the whales. 



The British Museum statistics cover the following localities and seasons : 



(a) Dependencies of the Falkland Islands. 



South Georgia, 1913-25 

 South Shetlands, 1918-24 ... 

 South Orkneys, 1922-26 



(b) South Africa. 



Cape Colony, 1920-25 



Natal, 1922-26 



Analysis of these figures gives the following results : 



(a) Dependencies of the Falkland Islands. 



Of all whales recorded 53 per cent were males. 



Of 22 seasons in different localities there were five with from 51 to 57 per cent of 

 females. One season had equal numbers of males and females. The remaining 16 

 seasons all showed a majority of males. Of these, 14 seasons showed 50 to 60 per cent 

 of males and two seasons showed between 60 and 70 per cent of males. 



(b) South Africa. 



Of all whales recorded 53 per cent were females. 



Of 14 seasons in different localities 10 showed a majority of females, all between 

 50 and 60 per cent. In the four remaining seasons there were 51 to 58 per cent males. 



From the above we see that while males have been found to be more numerous at 

 South Georgia and the other Dependencies, at South African stations larger numbers 

 of females have been taken. Among the Blue whales examined by us at both localities 

 there was a slight majority of females. 51 per cent of the whales and 60 per cent of 

 the foetuses were female. The results are therefore rather inconclusive though the 



