FUR-SEAL CENSUS, PRIBILOF ISLANDS, 1917. 105 



white than they had been the previous year. It is now believed that 

 the whiskers of both sexes turn white at about the same age. Thus in 

 most animals they be^in to turn in the fourth year and are entirely 

 white by the sixth. Iii size the 5-3^ear-olds appeared fully adult. 



HAREM AND IDLE BULLS. 



Many of the data contained in this and in all preceding reports on 

 the fur-seal herd have been derived from those classes of adult animals 

 known as harem and idle bulls. These comprise both the males which 

 are participating in the procreation of the species at the time of the 

 height of the breeding season, known as harem bulls or harem masters, 

 and that surplus skirting the margins of the rookeries which is unable 

 to get cows, known as idle bulls. 



Many facts go to make the adult male the subject of most trust- 

 worthy evidence respecting the seal herd. In the first place, he is 

 four or five times as large as the female and therefore easily seen at a 

 distance. Under average conditions of the sealing industry practi- 

 cally aU of the bulls haul out of the water on the breeding areas in 

 June and locate themselves 15 to 20 feet apart, where they stay until 

 about the first of August. Thus the entire number can be counted. 



In 1917 the average number of square feet of space occupied by 

 each bull and his harem was determined, and since 1912 the average 

 number of cows each one has been able to get has been obtained. 

 Figuring from these bases it is now possible to make a fairly accurate 

 census of the seal herd from a count of bulls alone at the height of 

 the breeding season. 



The count of bulls is known officially as the height-of-season harem 

 count or just harem count. A full realization of its importance is had 

 by all persons having knowledge of the fur-seal herd. It is very 

 important that it be made as nearly as possible on the same dates 

 year after year, and just as accurately as possible. It takes about a 

 week to make the count. 



Some rookeries are best counted from a boat, and others from a 

 long ladder held upright at various places. Those which give most 

 trouble are Zapadni and Reef on St. Paul, because the seals occupy a 

 sloping beach which can not be seen from behind and a table-land 

 which can not be seen from a boat. The crest between these areas 

 should be marked in some way to assist in this work. 



Preliminary counts are always made to acquire familiarity with 

 the general distribution of the masses and the approximate numbers 

 to be expected when the height of the season arrives. The dates 

 chosen as representing the height of the season have been well estab- 

 lished and mark the period when the largest number of bulls and cows 

 are present on the rookeries. 



Most of the harem bulls arrive and get into their positions on the 

 rookeries before any appreciable numbers of cows arrive at the islands. 

 The distance they were apart varied within the maximum and mini- 

 mum of 24 and 12 feet in 1917, and the average was 18 feet. Each one 

 knows the boundaries of his area, and any intrusion thereon promptly 

 starts a battle. The bulls were about four jumps apart. Naturally 

 when they are fewer they are farther apart and each one has more 

 cows. 



Those males actually having cows at the height of the season are 

 recorded as harem bulls whether they have one cow or a hundred. 

 Naturally with an abundance of buUs, as in 1917, there would be a 



