I08 BULLETIN OF THE BUREAU OF FISHERIES. 



On one occasion, on June ii, 1892, a fox was found on Walrus Island. Its activities 

 had prevented the birds from beginning to nest, and it was shot. On June 27, when 

 the island was next visited, a boatload of eggs was gathered. 



DISEASES. 



The main cause of the decline of the fox herd, lack of food, has been sufficiently 

 discussed. Some diminution due to disease has taken place, but apparently there has 

 never been any serious epidemic. Deaths of occasional individuals occur from tuber- 

 culosis, hemorrhage, or other affections of the kidneys, and ulcers of the stomach or 

 intestines. Mange, or a similar disease, has appeared at infrequent intervals, and has 

 undoubtedly caused the death of many. It was prevalent on St. George in 191 4. 



Under this head cannibalism, although undoubtedly due entirely to lack of proper 



food, may be considered. It has caused a serious loss on a few occasions, the most 



notable occurring on St. George in the autumn and winter of 1913-14, when several 



hundred were estimated to have perished from this cause. At this time the foxes were 



being supplied plentifully with salted food. This apparently had been imperfectly 



freshened and was not relished by the animals. It is certain that salt is injurious to 



foxes, and it is not unlikely that the eating of salted food induced a diseased condition 



similar in effect to scurvy, and that the craving for fresh meat led to cannibalism. 



During the spring of 19 14 the number of foxes observed was unusually small, and many 



were in poor phvsical condition. 



FOOD. 



Seal meat. — Under the conditions prevailing for many years on the Pribilof Islands, 

 while large numbers of seals were killed" every season, the thousands of bodies which 

 were left on the killing fields constituted the main source of food for the foxes. To this 

 abundance the islands owe their eminence as a fox nursery. During the few years 

 immediately following 1890, coincident with a reduced catch of seals, a great diminution 

 in the numbers of foxes on both islands was apparent, and although for several years 

 only a few animals were killed the numbers continued to remain at a low ebb. Although 

 other factors have contributed to their continued scarcity, there is no doubt that the 

 main cause has been the lessened quantity of seal meat available. Formerly no special 

 care was taken to preser\'e the meat, the bodies being merely left on the killing grounds 

 to be disposed of by natural processes, and the foxes securing their share as best they could. 

 But when it became evident that the diminution in the fox herd was due to the reduced 

 kill of seals, steps were taken to provide the animals with salted food of various kinds, 

 and seal meat was used as far as available. The subject of most effectively utilizing 

 surplus seal meat for fox food is elsewhere discussed. 



During the summer and early autumn the bodies of young seals dying from natural 

 causes on the breeding rookeries are eagerly devoured bv the foxes being eaten on the 

 spot or dragged to the dens for the young. 



Birds and eggs. — The foxes of the Pribilof Islands seem to prefer birds to any other 

 food. The greater abundance of birds on St. George seems to have been the direct cause 

 of the larger number of foxes taken on that island. During the spring and summer the 

 remains of birds, which are found about the burrows of the foxes in large numbers, testify 

 to the fondness of the animals for this food. The foxes are adept climbers and make 

 their way about cliffs which appear absolutely inaccessible to a quadruped. Manj- gulls. 



