58 BULLETIN OF THE BUREAU OF FISHERIES. 



and others with more than a hundred. If the bulls are of equal strength, one is as 

 capable of caring for a large harem as another, and it must be concluded that all bulls 

 have the ability to serve the maximum number of cows. This maximum number is 

 known to be more than loo, and although an exact figure can not be stated it is not 

 necessary for practical purposes that it should be. The average harem for the whole 

 herd or for certain of the larger rookeries is of value in this connection chiefly because 

 it substantiates the general conclusion that the maximum harem is very large. To 

 obtain the average harem of 59.8 in 1914, it is obvious that harems much larger than 

 the average must have been included. The maximum average harem of some of the 

 larger rookeries furnishes a further indication of the same sort. Thus, in 191 2 the 

 average harem of Tolstoi, a rookery of 9,074 cows, was 88.1; in 1913 the average harem 

 of Reef, with 13,984 cows, was 81.8; in 1914 Reef had 13,559 cows and an average 

 harem of 70.3. Such figures can not possibly be interpreted otherwise than that the 

 capacity of the bulls is^ar beyond their average opportunities even under present 

 conditions. 



In addition to the bearing cows, which are the only ones included in the average 

 harem, the harem bulls have the further responsibility of at least a small proportion of 

 the virgin cows; exactly how many can not be ascertained. If a sufficient number of 

 idle bulls were present to insure the exclusion of the half-bulls from the breeding, the 

 total of harem and idle bulls might be proportioned to the total of young and old cows 

 served by each bull. Under these conditions an average might be obtained by con- 

 sidering the bulls of one year as sires of pups of the next, and to this extent the effective- 

 ness of the bulls would be demonstrated wholly beyond cavil. Thus there were in 191 3, 

 according to count, 1,403 harem bulls, 105 idle bulls, and 259 young bulls, making a 

 total of 1,767 bulls and young bulls as the sires of the 93,250 pups born the following 

 year, in 1914. The average number of cows per bull on this basis therefore was 52.8 in 

 1 913. Two objections may be made to this result, (i) the number of young bulls counted 

 did not include the full stock of that class (see p. 40), and (2) at least 10 per cent of the 

 old cows must have died between seasons. One of these objections practically offsets 

 the other, and it would be hypercritical to dissent from the conclusion that an average 

 of not less than 50 young and old cows was served by the combined harem bulls, idle 

 bulls, and young bulls in 191 3. 



Considering all the data on the subject of average harems, it is evident that while 

 they fail to show the maximum capacity of the bulls they demonstrate most conclusively 

 that the maximum is very high and that in practice it has rarely or never been reached. 

 If any bad result has come through the reduced number of bulls on the islands in recent 

 years, it has not been because of lack of sexual power. Possible harm through lack of 

 opportunity by the old bulls and through participation of adolescent males in the breeding 

 has been discussed elsewhere (see p. 47). 



DISTINCTIONS BETWEEN THE CLASSES OF SEALS. 



The so-called classes of seals are the natural divisions which may be made according 

 to age and sex. For practical purposes there are seven classes of male seals and four classes 

 of females. The classes of males are the pups, the yearlings, the 2-year-old bachelors, 

 the 3-year-old bachelors, the 4-year-old bachelors, the 5 and 6 year olds or half-bulls, 



