FUR-SEAL CENSUS, PEIBILOF ISLANDS, 1917. 121 



body lengths will express little if any age relations because of the 

 variation in the sizes of bulls which are fully adult. That is, the 

 curve is then becoming a straight line which continues through the 

 rest of the seals' lives. 



SURPLUS BULLS. 



There were counted at the height of the breeding season 7,556 idle 

 bulls and harem bulls. Now, the hauling grounds and rookery mar- 

 gins were filled with other bulls over 6 years of age, but which could 

 not get close enough to the masses of cows to desire to hold positions. 

 Some had been whipped and injured on the rookeries and had resorted 

 to the hauhng grounds to recuperate. They were all left uncounted. 

 To complete the census, it becomes necessary to prepare an estimate 

 of this class, because they are included in no other. Heretofore it 

 has not been necessary to include such a category, because bulls 

 were not then superabundant. They were nearly all about the 

 rookeries, and the number left uncounted as idle bulls and harem 

 bulls was insignificant. But this was not the case in 1917. They 

 got in the drives to such an extent that they interfered considerably 

 with sealing work. These surplus bulls were largely 7 and 8 year 

 old animals, and may be best estimated by starting with the 6-year- 

 old males of 1916. 



The number of 6-year-old males in 1916 was 11,167. None was 

 'killed in the fall of 1916. In 1916 there was a total of 6,132 breeding 

 males. When there is an abundance of bulls, and consequently 

 much fighting, their breeding age is probably not over 8 years, ft 

 is not believed to be as long as the females, because the branded 

 males of 1901, 1902, and 1903 have not been as much in evidence 

 as the females. It may be even less than 8 years; no satisfactory 

 means of determining this question is known. By assuming that it 

 is 8 years makes it necessary to deduct 12-^ per cent (766) from the 

 6,132 bulls of 1916 for loss due to old age. This leaves 5,366 of the 

 1916 bulls for 1917. This deducted from the total bulls of 1917 

 (7,556) makes an increment of 2,190 necessary on the rookeries, and 

 they were derived in sufficient entirety from the 6-year-old class of 

 1916 to be taken from them. This leaves 8,977 of the 6-year-old 

 animals of that year unable to get on the rookeries, and they are 

 called surplus buUs. While it is known that not all of these were 

 7-year-olds which were hauled away from the rookeries, it is believed 

 that there were enough of this class which did not get cows or became 

 idle to offset the number of older bulls on the hauling grounds. And 

 while this computation may appear somewhat indefinite, no better 

 method has occurred by means of which the number may be arrived 

 at more satisfactorily. Most certainly these bulls on the hauling 

 ground can not be ignored and left unmentioned because they are 

 difficult to estimate. It is believed that the figure given is conserva- 

 tive and under rather than over the actual number. This class will 

 not continue longer than it takes to reduce the surplus of bulls now 

 obtaining by commercial sealing. 



