162 U. S. BUREAU OF FISHERIES 
During the last week of the season at St. Paul Island the 3-year-olds | 
continued to come in increasing numbers. The number killed at 
that time, however, doesnot show the number which were available; 
as the rookeries were badly broken up, no seals were driven from the | 
portions of rookeries having a considerable number of cows. 
The experience this year, when a great many 3-year-olds arrived 
after the rookeries were broken up near the end of the season, indi- 
cates the advantage of killing 4-year-olds instead of 3-year-olds. A 
more definite portion of killable seals could be secured by killing from 
the 4-year-old class, as these animals arrive much earlier in the season. 
This would also result in driving a smaller number of cows, a very 
important point to be considered. Cows do not withstand driving to 
the same extent as young males. A great many of the cows driven 
probably die as a result of extreme exhaustion. As previously recom-_ 
mended, therefore, the killing of 4-year-olds still appears advisable, 
if it should be considered desirable from a commercial standpoint. 
Through the courtesy of the Commander of the Bering Sea Patrol 
and the commanding officer of the Coast Guard cutter Spencer, an air- 
plane made a trip from the village landing to Northeast Point and 
return. The plane passed over the Polovina rookeries en route and 
made several trips over the Northeast Point rookeries, for the purpose 
of ascertaining if it would be practicable to make a pup count by taking 
pictures from a plane. Motion pictures and still pictures were taken 
by the Coast Guard, but it appears that the value of such pictures in 
connection with a census of the fur seals is limited. The black rocks, 
on which most of the seals are found, are so dark that there is prac- 
tically no contrast between them and the black pups. In addition, 
the pups are so small that they cannot be seen from a plane. The 
seals were not bothered in the least from the noise of the plane. 
Adult sea lions, because of their light color, were easily distinguished 
from the plane, but all of them made a dash for the water when they 
heard the plane overhead. 
BULLS 
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Insofar as possible, a count was made of all harem and idle bulls. | 
During the counting period at St. Paul Island, harems were increasing 
and cows were being held in place by the active harem bulls. A couple 
of days of warm weather, however, caused a break-up of the St. George 
harems before counts could be made. It was necessary, therefore, to 
apply to St. George the information obtained at St. Paul, after observ- 
ing the actual harem areas occupied. 
On certain St. Paul rookeries harem areas were greatly extended, 
while on others considerably less area was covered than in the previous 
vear. Female seals prefer to crowd together as closely as possible. 
Therefore, the crowded areas grow faster and contain many more seals 
per square foot than other portions of the rookery which would appear 
to be more favorable for their requirements. A cow prefers to enter 
a large harem rather than to go to a bull with only a few cows or none 
at all. The favored harems finally become so large that the cows must 
enter another bull’s domain. Then the unfavored one soon accumu- — 
lates a much larger number. , 
This year, it will be noted, there was practically no increase in the 
number of harem bulls and there was a marked reduction in the num- — 
