54 THE FUR SEALS OF THE PRIBILOF ISLANDS. 
FLUCTUATIONS OF POPULATION. 
The daily counts of the breeding season of 1897 may here again be cited to give 
an idea of the real condition of the rookeries at their maximum. The following figures 
are for that part of Kitovi rookery called the Amphitheater, which contained, 
according to the count of pups made on August 3, about 1,245 breeding females for 
the season: 
Amphitheater of Kitovi. 
. Cows 
present. 
Date. 
July 10 
nS ee 
Such is the height of the season. The actual count shows a difference of 6 per 
cent between its beginning and its maximum and a difference of 38 per cent between 
the maximum and its close, while between two individual days of the period there is 
as great a difference as 20 per cent. é 
INCREASE OF FAMILIES. 
Nor is the fluctuation in individuals all that is to be noted in this consideration of 
the height of the season. The following count of harems on this same breeding 
ground shows equally important results: 
Amphitheater of Kitovi, 1897. 
Date. | Harems. 
! 
| 
| 
Tt is thus apparent that during this time of supposed rookery stability the 
number of harems underwent quite as marked a change as did the number of indi- 
vidual animals composing them. The daily observations of this breeding ground and 
frequent photographs of its area show, moreover, that the extent of ground oceupied 
grew steadily from day to day. 
WHAT THE HEIGHT OF THE SEASON MEANS. 
What the height of the breeding season really means, therefore, is a time in 
rookery development when the stream of incoming cows about equals the stream of 
outgoing ones. Itis the time when the greatest nuinber of cows are actually present 
at one time. It marks the maximum of rookery development, which probably covers 
