THE SOUTHERN SEA LION 155 



cows are present in the collection of sexually active animals. It has been suggested that 

 one factor may be the increased intensity of the light in summer, and in connexion with 

 this it would be of the greatest interest to know the habits of Otaria byronia in Galapagos, 

 which is almost on the Equator. 



The significance of the " teratocytes " in the testes is unknown, but they occur only 

 in the season when there is no breeding, except perhaps in the rarest cases (p. 142). 



CENSUS OF THE HERD IN THE FALKLAND ISLANDS 

 THE COUNT OF PUPS 



It is perhaps hardly necessary to state that the most accurate basis for an estimate of 

 the population is a count of pups, since they are the only class of seal of which the whole 

 is ashore at one time. I find that such counts can be carried out during a period longer 

 than that indicated on p. 309 of my previous report: they are satisfactory if made 

 between the end of pupping, say 21 January, and the end of February, a period when 

 the harems have broken up and the pups are collected in groups, more correctly " pods ", 

 which may contain any number from a mere handful of animals to hundreds. 



It must be taken as a general rule that pups cannot be counted at high water. Some 

 scope of beach is necessary for handling them. If the animals are confined to the beach 

 matters are easier than when they have gone up into the tussac grass which is the usual 

 background ; and the seal are very fond of doing so. The principal difficulties lie in 

 the agility of the pups and the sometimes alarming obduracy of adults, especially the 

 more aggressive males. 



The method depends on getting rid of the older seals without allowing the pups to 

 escape, and this is possible only on account of the lower speed of the latter. When the 

 seals are only on the beach the separation can be achieved by approaching them from 

 the water briskly and rather noisily so as to produce a general stampede, which is always 

 directed towards the sea ; the pups get left behind and are cut off and driven up the 

 beach. A watch should be kept for any that escape and their number noted. When the 

 pups have been collected in this manner they are allowed to escape so that they can be 

 counted as they go, that is, either in a thin steady stream or in small groups. Numbers 

 are written down whenever there is a cessation of counting for any reason at all, even if 

 there is but one to record. Full use should be made of natural features such as large 

 boulders, clay banks, walls of rock and so on which will serve to contain the pups. 



Seals in the tussac must be driven out on to the beach and there separated, but the 

 ground must be searched after the general rush, since some animals manage to sleep 

 through the uproar and it is a disadvantage to have even pups rushing down suddenly, 

 and something more than a disadvantage if a large and alarmed bull suddenly appears. 



There is a great variation in the ease with which different rookeries can be counted. 

 Those which show a considerable length of flat beach are the best ; some can be counted 

 by only two men but four is a far better and more efficient number. 



A certain delicacy has to be observed in dealing with crowded pups, since too close 



