FUR SBAI,S AND OTHER LIFE, PRIBILOF ISLANDS, 1914. 

 Mortality of pups, summer of IQI4. 



71 



It will be seen from this table that the mortality of pups up to about August 5 

 was 1.8 per cent of the total number bom and that no rookery diverged far from this 

 percentage. The highest death rate was on Lukanin, 3.9 per cent, and the lowest on 

 Lagoon, 0.5 per cent. These figures show conclusively that during the season of 1914 

 there were no noteworthy epidemics of any kind among the pups. 



The dead pups were usually found on the rookery grounds, and often gave evidence 

 of having been dead several weeks. Some few, particularly on Reef and on Tolstoi, 

 had been dragged away by the foxes and their remains were found at the mouths of the 

 fox burrows on ground adjacent to the rookeries. As there was no evidence of any 

 epidemic, the dead pups were not especially examined. It is probable, as Marsh has 

 pointed out (Science, vol. 36, p. 397, 1912), that starvation, asphyxia neonatorum, and 

 crushing by roclys and landslides are the chief fatal accidents of early life, and that 

 uncinariasis is the principal fatal disease of this period. In a report made by Marsh in 

 1912 to the Department of Commerce and Labor on the causes of death of 175 pups 

 examined in that year, 81 (46 per cent) were believed to have died of starvation, 24 

 (14 per cent) of asphyxia neonatorum, 19 (11 per cent) from accidents due to landslides, 

 etc., and 12 (7 per cent) to uncinariasis. These four causes were believed to be the chief 

 occasions of death among the young pups in the season of 191 2. Since the death rate 

 in that season was estimated at 1.2 per cent of the total number of pups bom, and since 

 in 1914 this rate was much the same, 1.8 per cent, it seems probable that the causes 

 of death already enumerated have continued to act in 1 914 as in 191 2. 



An inspection of the table will show, as already pointed out, considerable uniformity 

 so far as the death rates of the various rookeries are concerned. The chief divergences 

 in the direction of larger numbers are to be seen in Little East Rookery on St. George, 

 and in Lukanin and less so in Vostochni on St. Paul. In Little East Rookery the condi- 

 tion is a mere accident due to the small total number of pups present and in Lukanin, 



