664 POPULAR SCIENCE MONTHLY. 



young, with such also as have recently lost their young through the vari- 

 ous causes of natural mortality. 



This statement is put in the mildest possible form out of con- 

 sideration for the old-time British contentions that the breeding 

 females did not leave the islands while their young were dependent 

 upon them, and that those taken at sea were " barren." The inves- 

 tigations of 1896 and 1897 proved conclusively that every female 

 of two years old and over taken at sea was pregnant, and that those 

 over two years of age when taken in Bering Sea were in addition 

 nursing, having dependent pups on the islands. The manner of 

 statement seems to imply an equality in importance between 

 " young " seals and " adults." As females are never killed on land, 

 they are naturally of all ages when found at sea, and the young 

 animals (yearlings and two-year-olds) are necessarily vastly in the 

 minority. 



13. The polygamous habit of the animal, coupled with an equal birth 

 rate of the two sexes, permits a large number of males to be removed with 

 impunity from the herd, while, as with other animals, any similar abstrac- 

 tion of females checks or lessens the herd's increase, or, when carried 

 further, brings about an actual diminution of the herd. It is equally plain 

 that a certain number of females may be killed without involving the 

 actual diminution of the herd, if the number killed does not exceed the an- 

 nual increment of the breeding herd, taking into consideration the annual 

 losses by death through old age and through incidents of the sea. 



This paragraph is really supplementary to 9 and 11. Neither 

 the methods nor yet the principle of land killing are at fault. The 

 animal being polygamous, a part of its male life can be removed with 

 impunity. On the other hand, the killing of females leads to dis- 

 astrous results. 



The concluding sentence is a concession to diplomacy. It is 

 true that a certain number of females may be killed without pro- 

 ducing actual diminution. If pelagic sealing were stopped to-day the 

 herd would naturally begin to increase. The measure of its increase 

 would be the difference between the natural loss of adult breeders 

 through old age and incidents of the sea, on the one hand, and the 

 yearly accession of young breeders to bear their first pups, on the 

 other. We can closely estimate the latter factor. It was equal, for 

 example, to the quota of 20,000 in 1897, or sixteen and two thirds 

 per cent of the birth rate. The quota was composed of males of ap- 

 proximately three years, and we may assume that a like number of 

 three-year-old females entered the rookeries for the first time in the 

 same season. We have then a gross gain to the breeding herd of 

 sixteen and two thirds per cent. 



We have no means of exact estimate for the loss of adult females 



