ZOOLOGY: G. H. PARKER 
171 
1 shows, that it is not the count of 1914 that is anomalous but that of 1913- 
Why this should be so extraordinarily high is difficult to state. It is per- 
fectly clear to any one who has counted pups on the rookeries of the Pribilofs 
that even the most accurate count is bound to fall short of the real num- 
ber, so that the magnitudes indicated by the dotted line between 1912 and 
1917 in Graph 1 show the directions in which the real numbers lie rather 
than the solid line of actual enumerations. But even admitting that all the 
enumerations, except that of 1913, are low, there is no reason to suppose that 
these are so far low as would be implied on the assumption that the count 
of 1913 is the most nearly accurate count of them all. It seems impossible 
that Clark should have improved his method so much between 1912 and 1913 
as to have found as large an increase as is implied in the count of 1913. Such 
increases based on assumed improvement in method do not appear among the 
several counts by Hanna. But in whatever way this discrepancy in the counts 
may be explained, it must at least now be clear that the count of 1914 agrees 
well with the majority of the other enumerations and that the count that is 
exceptional is that of 1913. 
Another way of indicating the growth of the herd as seen in the numbers 
6f pups, is the percentage of annual increase in this constituent. From time 
to time statements have been made as to what this percentage under normal 
conditions should be. Thus Clark (1917, p. 499), selecting the increase in 
1913 (12.5%) and in 1916 (13.0%), concluded that these figures "may be 
taken as fixing with reasonable exactness the rate of growth at about 13%." 
Hanna (Bower and Allen, 1917, p. 92) has expressed the opinion that about 
12% is the normal rate of increase. How these numbers compare with the 
actual figures of the last five years can be seen in table 2. 
TABLE 2 
Increase of Pups in the Alaskan Fur Seal Herd from 1913 to 1917 Inclusive 
YEAR 
NUMBER OF 
GIVEN YEAR 
PUPS IN THE 
| PRECEDING YEAR 
ACTUAL 
INCREASE 
PERCENTAGE INCREASE 
1913 
92,269 
- 81,984 
= 10,285 
12.5+ 
1914 
93,250 
- 92,269 
- 981 
1.1- 
1915 
103,527 
- 93,250 
= 10,277 
11.0+ 
1916 
116,977 
-103,527 
= 13,450 
13.0- 
1917 
128,024 
-116,977 
= 11,047 
9.4+ 
9.4 
Here it will be noted that the percentage increase varies from 1.1 to^l3.0 
with an average of 9.4. This computation included the very anomalous 
count of 1913, but even if this were replaced by a number such as would be 
indicated by Graph 1 (86,000) such a replacement would not materially alter 
the general average. The percentage increase in 1913 would then be 4.9 
