398 CALLORHINUS URSINUS NORTHERN FUR SEAL. 



injury prevailed, and as the product of 1877 will not arrive at 

 the proper age for killing until 1880, it must be left to the 

 future to determine the extent of the loss. 



" CAUSES OF THE CHANGES IN THE HABITS OF THE SEALS, 

 ETC. It will now be well to try and trace some of the causes that 

 operated to produce changes in what had been the usual habits 

 of these animals. At the date of the transfer of these islands to 

 the United States the non-breeding Seals (and by this class I 

 mean the males of all ages not in active service on the breed- 

 ing-places) were, as nearly as can be ascertained, equal to 

 the whole number of both beachrnasters and females. Thirty 

 per cent, of this non-breeding class were capable of pro- 

 creation. During the years 1867, 18G8, and 1869 there were 

 taken 410,000 Seals, mostly of the product of 1866, 1867, and 

 1868. This large number killed in so short a time, left only a 

 small portion of the product of those years to mature, to furnish 

 the half-bulls in 1871, 1872, and 1873. During these years (the 

 first years under the lease), the demand, for reasons before 

 stated, was for large skins, and it had to be met by killing four-, 

 five-, and six-year-olds. This destruction of the remnant that 

 escaped from the excessive killing in the years of 1868 and 1869 

 had the effect to exterminate the product of those years and 

 create a chasm that had to be bridged over by the products 

 of years prior to 1865, which had to supply the males neces- 

 sary for breeding, until the products of later years could ma- 

 ture. Again, during the season of 1870 the natives, to pur- 

 chase supplies and for their own food, killed 85,000, mostly one- 

 and two-year-old Seals. This operated in the same direction, 

 reducing to a minimum the products of 1868 and 1869, and 

 rendering the breach still wider. There was consequently only 

 a limited number to fill this gap until those spared by the com- 

 pany in 1871, 1872, and 1873, when only half-bulls were taken, 

 had matured. Before these had time to attain maturity the 

 large surplus of reserves of the year 1869 became so reduced 

 in numbers by natural causes as to induce the changes we have 

 noted in the movements of the female breeding Seals. The old 

 males, having become weakened and exhausted, failed to im- 

 pregnate the females in their first heat and forced them to seek 

 the younger males in their second heat instead of going to the 

 beaches with their young as formerly. This caused many fe- 

 males to bear their young later in the season, and consequently, 



