FORMER MORTALITY NOT NOTICED. 81 



On rocky ground the embryos are readily blown or washed off, while on bowlder 

 beaches, such as the Lagoon and Zapadui Eeef, the embryos are still more readily 

 washed away, while many fall among the crevices of the rocks at the outset and are 

 lost. There is thus much less chance of the embryos being present to adhere to the 

 coats of the female seals, while on rough ground the seals are also unable to pack as 

 closely together as on flat places. The relation between the character of the ground 

 and Uncinaria maybe shown by the comparison of, one rookery with another or by 

 the comparison of the deaths on St. George with those on St. Paul. For example, we 

 did not find a single case of Uncinaria on Lagoon rookery, which is composed of 

 rounded bowlders, while on Tolstoi Sand Flat 52 out of 109 pups examined contained 

 Uncinaria, and there were 44 deaths from that cause alone. On comparing Big 

 Zapadni with Zapadni Reef we find that on the first-named tract, which comprises 

 much sand, 16 out of 25 deaths were from Uncinaria and parasites were present in 3 

 other cases, while on Zapadni Eeef, which consists largely of bowlders, but 2 out of 12 

 deaths were due to Uncinaria, and these 2 occurred at the eastern end, where the 

 bowlders are interspersed with sand. 



Taking the death rate of the two islands as a whole, the number of dead pups 

 found on St. George in 1896 was only 735, while on St. Paul it reached the astonishing 

 number of 10,309, this great difference being solely due to the character of the breed- 

 ing grounds. On St. George the rookeries are located almost exclusively on bowlder 

 beaches or on solid rock, seldom, in their now depleted condition, comprising any 

 extent of sand. On St. Paul, on the contrary, a large portion of the seals occupy 

 ground that is either sandy or consists of sand interspersed with bowlders. This 

 rocky character of the rookery ground on St. George and its practical freedom from 

 Uncinaria is probably the reason why this island has afforded a greater number of 

 skins in proportion to the size of the hauling grounds than has St. Paul. 



As the damage done by Uncinaria bears a direct relation to the character of the 

 ground and the number of seals present, the losses from this cause in past times must 

 have been enormous, although in most places there is little apparent evidence of past 

 destruction. Still, when one stands on the slope above the eastern end of Tolstoi and 

 looks at the sands below they seem gray with the whitening bones of thousands of 

 pups, thus mapping out territory occupied when the rookeries were in their prime, 

 part of which has been vacant for at least eight years. 



These seals, dead from Uncinaria, are those seen by the British commissioners in 

 1891 and 1892, and also by Colonel Murray in the latter year, and they are the dead 

 seen on Zapadni and Polovina scattered along the edges of the breeding grounds. 



That this great mortality has gone on year after year practically unnoticed is not 

 so remarkable as it might seem. At the time the deaths are most numerous it is quite 

 out of the question to enter the rookeries, and most of the dead are hidden from view 

 by the dense masses of breeding seals, while naturally the more abundant the seals, 

 as in years gone by, the more difficult would it be to examine the breeding grounds. 

 During the period of rookery expansion, when the rookeries are largely clear, they 

 are avoided in order not to disturb the seals which have drawn back over the adjacent 

 territory, and after the breeding season is over no attention seems to have been paid 

 to the rookery grounds ; hence year after year thousands of pups have died and no 

 one has been any the wiser. And unless one has actually gone over a rookery foot 

 by foot and counted every dead seal, he will fail to realize the numbers present. 

 5947— PT 3 6 



