80 U. S. BUREAU OF FISHERIES. 



Distribution of pups on Pribilof Islands in 1921 and comparison vnth distribution in 1920. 



Rookery. 



ST. PAUL ISLAND. 



Kitovi 



Lukanin 



Gorbatch 



Ardiguen 



Reef 



Sivutch 



Lagoon 



Tolstoi 



Zapadni 



Little Zapadni 



Zapadni Reef 



Polovina 



Polovina Clift's 



Little Polovina 



Morjovi 



Vostochni 



Total. 



ST. GEORGE ISLAND. 



North 



Staraya Artil 



Zapadni 



South 



East Reef 



East Cliffs 



Total. 



Total (both is- 

 lands) 



Date of 

 count. 



Living 

 pups. 



Aug. 5 



Aug. 5 

 Aug. 7 

 ...do... 



Aug. 6 



4,300 

 2, S.59 



10,610 

 1,072 



24, 022 



8,755 



2S6 



15, 356 



16, 453 

 9,812 

 4,86 

 5,912 

 2,717 

 1,655 

 2,942 



38, 788 



146, 025 



Dead 

 pups. 



53 



79 



299 



16 



616 



99 



1 



352 



377 



225 



16 



159 



68 



21 



52 



1,407 



3,840 



July 30 

 ...do... 

 Aug. 1 



9,787 

 6,439 

 884 

 184 

 2, 594 

 6,345 



26,233 



199 



181 



11 



3 



34 

 129 



Total 

 pups. 



1 4, 353 



12,938 



MO, 909 



1 1,088 



1 24,638 



1 8, 854 



287 



1 15,708 



1 16, 830 



1 10, 037 



502 



6,071 



2,785 



1 1,676 



2,994 



1 40, 195 



149, 865 



' 9, 986 



16,620 



895 



187 



2, 628 



1 6, 474 



26,790 



Per cent 

 dead 

 pups. 



1.22 

 2.69 

 2.74 

 1.44 

 2.50 

 1.12 

 .35 

 2.24 

 2.24 

 2.24 

 3.19 

 2.62 

 2.44 

 1.23 

 1.74 

 3.50 



2.55 



1.99 

 2.74 

 1.23 

 1.60 

 1.29 

 2.00 



2.08 



2.48 



1920: 

 Total 

 pups. 



3,764 



2, 932 



10, 251 



1, 180 



23,638 



8,375 



341 



17, 286 



16, 299 



12, 494 



.532 



6,006 



2,573 



1,711 



2,936 



32, 857 



143,275 



9,126 

 5,944 

 907 

 99 

 2, 571 

 5,605 



1921 



Numeri- 

 cal in- 

 crease. 



589 



6 



658 



-92 



1,000 



479 



-54 



-1,.578 



431 



-2,4.57 



-30 



65 



212 



-35 



58 



7,338 



6,590 



Per cent 

 increase 

 (-l-)or 

 decrease 



-f 15.65 

 -I-.20 

 -h6.42 

 -7.79 

 -1-4.23 

 -(-5.72 



-15.84 

 -9. 13 

 -f2.63 



-19.67 

 -5.64 

 -Hi. 08 

 -1-8.24 

 -2.05 

 -1-1.98 



-1-22.33 



-1-4.60 



860 

 676 

 -12 



2,538 



-f9.42 

 4-11.37 



-1.32 

 -f88.89 



-1-2.22 

 -fl5.50 



-10.47 



167, 527 



9,128 



4-5.45 



1 Based on estimated average harem. 



The percentage of dead pups is practically the same as it was in 

 1920. A decrease of 0.04 per cent for both islands is shown. This 

 was to be expected, since there was no change in the conditions gov- 

 erning the percentage of dead pups that would materially increase or 

 decrease the number. 



The great variation of increase or decrease in the number of pups 

 born on the various rookeries is remarkable. On St. Paul Island 

 Vostochni rookery shows an increase of 22.33 per cent, while Little 

 Zapadni rookor}^ shows a decrease of 19.67 per cent. On St. George 

 Island South rookery shows an increase of 88.89 per cent. It can not 

 be said that the methods of computation are responsible for this 

 variation, because the rookeries where pups were actually counted 

 show the greatest variation. South rookery increased 88.89 per cent, 

 while Lagoon rookery decreased 15.84 per cent. Neither of these 

 rookeries has a hauling ground, and each was practically undisturbed 

 during the breeding season. 



COWS. 



The number of breeding cows is the same as the number of pups, 

 since a cow gives birth to a single pup annually and since barren cows, 

 if there are any, do not affect the size of the herd. While countii;g 

 the pups 11 dead cows were found. With 16,349 live cows on these 



