FUR SEALS AND OTHER LIFE, PRIBILOF ISLANDS, I914. 



81 



size of the reserve should increase from year to year at a rate proportionate to the rate 

 of increase of the cows. After a few years of experimentation this rate could be deter- 

 mined. To indicate our present knowledge of rates of increase and to serve as a guide 

 to be used according to circumstances in making reser\^es, the following tables have been 

 prepared. Although they furnish a forecast of possible future conditions, this is not 

 their primary purpose, and it is hoped that they will be regarded less as predictions than 

 as demonstrations that whatever the rate of increase the reserve of males should be 

 relatively small. 



Table No. i. — Estimated minimum number of females, igi4-iQ26fi 



Bearing cows 



virgin cows 



Total breeders , . . 

 Yearling females . 

 Female pups 



^ 93)250 

 17,422 

 110,672 

 23,068 

 46,625 



97, 740 

 19,607 

 117,347 

 23,312 

 48,870 



1916 



103,658 

 I9>8is 



123,473 

 =4.435 

 51,829 



109,053 

 20,770 



129,823 

 25.914 

 54.526 



1918 



114,660 

 22,027 



136,687 

 27.263 

 57,330 



120, 72s 

 23,174 



143.899 

 28.665 

 60, 363 



Bearing cows . . . 



virgin cows 



Total breeders . , 

 Yearling females 

 Female pups . . . . 



127.095 

 24,365 



151,468 

 30,182 

 63,548 



133.773 

 25,655 



159,428 

 31.774 

 66,887 



140,810 

 27,008 

 167,818 



33.444 

 70, 405 



148.220 

 28,427 



176,647 

 35.203 



74,110 



156,019 

 29.923 



185.942 

 37, 05s 

 78,009 



164, 228 

 31.497 



195,725 

 39.005 

 82,114 



1926 



172,867 

 33.154 



206,021 

 41,057 

 86, 434 



« Based on assumed mortality of 50 per cent in first year. 15 per cent in second year. 10 per cent in third year, and 12 per cent 

 annually thereafter; annual rate of increase of cows 5 per cent to 6 per cent. 

 *> Based on actual count of pups. 



Table No. 2. — Estimated maximum number of females , lC)l4-ig26fi 



1916 



1918 



Bearing cows 

 virgin cows . . 

 Total cows . . , 

 Female pups . 



93,250 



24.255 



117,505 



46, 625 



10S.755 

 27,681 



133,436 

 52,877 



120,093 

 27.975 



148, 068 

 60,046 



133,261 

 31.726 



164,987 

 66,630 



148,488 

 36,027 



184,51s 

 74,244 



166,064 

 39,978 



306, 043 

 83,032 



1926 



Bearing cows 

 Virgin cows. . 

 Total cows . . 

 Female pups. 



185.438 

 44.546 



229,984 

 92,719 



206,986 

 49, 819 

 256,805 

 103,493 



231,125 

 55,631 

 286, 756 

 "5.562 



258,080 



62,093 



320,175 



129,040 



288, 158 

 69,337 



357,495 

 144,079 



321,746 



77.424 



399. 170 



160,873 



359.253 



86, 447 



445.700 



179,626 



» Based on assumed mortality of 40 per cent in first two years and 10 per cent annually thereafter; annual rate of increase of 

 cows 11 per cent to 12 per cent. 



Table No. 3. — Estimated mean number of bearing and virgin cows, igi4-igz6.'^ 



Total cows: 



1914 & 114,088 



191S 123,21s 



1916 133.072 



J917 143,718 



1918 155, 215 



1919 167,633 



1920 181,043 



a Based on a rate of increase of 8 per cent per annum, this being the appro.ximate mean between the rate of the minimum 

 estimate and the rate of the maximum estimate. 



^ Mean between maximum and minimum estimates. 



Total cows — Continued. 



1921 19s, 527 



1922 211,169 



1923 228,062 



1924 246,307 



1925 266,01a 



1926 387,293 



