FEEDING OF THE FUR SEALS. 55 
no more than a single day. In observing the rookeries the eye can not adjust itself 
readily to the change, and the result is that the period seems to comprehend several 
days. 
From about the 10th or 12th of June onward new cows are constantly arriving 
on the rookeries. About ten or twelve days after her arrival each cow goes away to 
feed for the first time. The first arrivals and first departures therefore run roughly in 
parallel lines. A disturbing element is brought in by the return of cows from feeding 
and their subsequent departure and return at intervals. All these various elements 
result in a period of apparent equilibrium at about the 15th of July, which is the 
height of the season. 
THE PERIOD CURRENTLY MISUNDERSTOOD. 
That this period of rookery development should have been misunderstood is not 
strange, since the matter was never before tested by mathematical standards. 
Events in rookery life, though recurring by the thousands, are difficult of observation. 
Their very multitude distracts the observer. In the summer of 1897, at the maximum 
period of rookery life, when thousands of pups were being born, the closest observa- 
tions, extending at times through nine hours a day, failed to disclose the actual 
birth of more than a dozen pups. Under this same close scrutiny it was a week 
after the first landing of cows before one could be discovered in the act, and a much 
~ Jonger period elapsed before the departure of one could be observed. General 
observations of the rookeries have therefore only relative value unless they are 
checked by figures. They can be trusted to show large results, but can not be relied 
upon to indicate normal changes. To get definite results, exact enumerations and 
minute observations are necessary. 
THE BIRTH OF THE PUP. 
Within a period of from six t» forty-eight hours after her arrival the cow gives 
birth to her pup. After a further period of five to six days she comes in heat and is 
served by the bull. Five to six more days pass, during which time the pup grows 
rapidly and becomes able to take care of itself; then the mother goes to sea to 
bathe and feed. Her first return is possibly en three or four days. Of her 
subsequent returns no record has been possible, but from the gradual decrease in the 
number of cows present after the height of the season is reached, it must be inferred 
that the time of absence lengthens as the pup grows older and is able to remain 
longer without food. As the cow does not leave the harem until after impregnation 
it necessarily follows that adult cows whenever found at sea are pregnant. 
TEE FEEDING OF THE COWS. 
When the cows first enter the water after their long rest on the shore they exhibit 
every evidence of genuine satisfaction and pleasure. They do not at once swim away, 
but play about, rolling over and over in the water, scratching and rubbing themselves 
with their flippers, getting thoroughly cleaned from the filth of the rookeries, This 
done, the animals swim away to the feeding grounds. 
SWIMMING SEALS. 
During the breeding season a band of sleeping, playing, or swimming seals 
skirts each rookery front. Some are plainly bachelors, but most are cows. This 
