FUR-SEAL CENSUS, PRIBILOF ISLANDS, 1918. 117 
able information that this is about as low as it can go. As long as 
the percentage of nonbreeding bulls to breeding bulls remains as 
high as it has been in these two years there is no probability that the | 
average harem will materially change for the herd. 
There is a general stability or sameness developing on the rookeries 
due to the excess of bulls, and the deviation of the average harem on 
certain rookeries from the general average seems now to be due 
largely to topography of the breeding areas. This is indicated by 
the similarity of the average harems on rookeries counted the past 
two seasons. 
Since pups could not be counted on all rookeries, the average harem 
had to be computed for many of them. On account of the closeness 
of the 1917 and 1918 figures on those areas counted it was placed at 
the same as the 1917 figure in most cases. The only exceptions to 
this rule were in those cases in which field observations were con- 
vincing proof that the 1917 condition was abnormal and had 
disappeared. 
Since so many factors relating to the pups are directly dependent 
upon the average harem, this has formed the basis of most of the com- 
putations found in the following tables. Thus it is well known that 
the percentage of dead pups on a given rookery is dependent on the 
topography of the rookeries, the number of harem bulls, and the 
average harem. With these factors constant, the percentage must 
be constant when pelagic sealing is nonexistent and no epidemic 
occurs, no evidence of either of which was observed in 1918. There- 
fore it seems justifiable to place the percentage of dead on rookeries 
not actually counted at the same as was carefully computed for 1917. 
This brings it to 3 per cent for the herd. 
DISTRIBUTION OF Pups IN 1918. 
Living Dead Total | Percent- 
Rookery. Date of counts. pups. pups. pups. |age dead. 
ST. PAUL ISLAND, 
ALOUD yr Sea re = Me Ba RS et EO UE raat Nee. A ee a 2,502 38 | 22,540 1.49 
Tope eyo oes seen aaa ee ek ate cock eee ob wae 2,174 61 @ 2,235 2.42 
Gorbatch Dee re pate cree ava SNS ia = oo IES latalnl| a wtoraleone Setanta = <catatare 9,154 332 a9, 486 3.49 
AIT Eeerd ON e ceees ie Se CE EP NLS URS RR Ya 778 14 a 792 1.76 
Reef 2 eae een 2 Sy eI De ae SS A A Aer es Aug. 9-10.......-.- 18, 890 508 19,398 2.61 
Siyatehts-sase4 sae ADA anteaeines Paak e eee § 2 SS aaa 6, 167 158 | 96,325 2. 49 
Dapagn sie ck ee ee ke eee obra ee 493 19 512 3.71 
pC SRI De RRR eth Sena = a ae, SSR 16, 349 376 | © 16,725 2.24 
DATE ee aetna anata ars seepe nero acs © | emer oe ote 11, 156 304 | @11, 460 2.65 
Little Zapadni NT oa a ier e oo ia ait SS Se oral ee a ee arabe ee eee ee oe 8,795 294 29,089 3.23 
ARPAG Replies. yews Lk esses ae AUG Ses Joss Geen 517 19 536 3.54 
POlOVsUa ans sess cn oaeee cae eee eee ete TAI SI kn 5,191 152 5,343 2. 84 
Poloving Cliffs... l2.c.2. /Wataes op oeek amen: Eee eee eee 1, 824 58 | 1,882 3.08 
Little Polovina eee Stel Bae bet EPICS one lllons Galena in Re eee 1,473 18 a 1,491 1.20 
MGI Gyles ae ss tiais, tare nee eet ow | stat ae serene etre os 3, 224 111 | 23,335 3.32 
SI ViGSHOCHITTE eee tie 2 te Sante ee Eo a RR: 30,057 | 1,411 | 431,468 4. 48 
ET ee a aaa ieee care aoe ae 118,744 | 3,873 | 122,617 3.15 
North 
Staraya Artil 
apadni 
South 
East Reef 
AYALISIS ESATA ISICTE Cs RS CRI (NES i eee ea 138, 613 4,302 | 142,915 3.01 
a Based on estimated average harem, 
