BUREAU OF BIOLOGICAL SURVEY. 267 



game and would appear permissible only nnder extraordinarily 

 serious conditions, such as have not yet developed. 



In maintaining the bird reservations the bureau has continued, as 

 during previous years, to receive the generous and active assistance 

 of the National Association of Audubon Societies. Owing to the 

 claim that many of the birds protected on Federal bird reserva/tions 

 were large destroyers of useful food fishes, the secretary of that 

 organization has worked in cooperation with the bureau in investi- 

 gating the food habits of these birds, and has visited a large number 

 of bird reservations for the purpose of securing information to be 

 used in a cooperative report on them. From present indications this 

 report undoubtedly will show that there is small basis for most of 

 the assertions which have been made as to food-fish destruction by 

 these birds. 



MAMMAL RESERVATIONS. 



Winter Elk Eefuge, Jackson, Wyoming. — The elk came down 

 from the mountains in their usual migration in the fall, but instead 

 of halting among the foothills until near midwinter they proceeded 

 in unprecedented numbers directly from the summer ranges to Jack- 

 son Hole Valley. Late in December many large herds had already 

 collected on the refuge and in the adjacent country. Subsequent 

 investigations showed that the foothill country ordinarily used by elk 

 in autumn and early winter had been covered by an unusually early 

 blanket of wet snow which had packed and become crusted until it 

 was almost impossible for the elk to dig through to the forage. This 

 was the reason for their early descent to the lower grounds. 



During fall and early winter the weather was unusually mild, 

 enabling the elk to obtain full benefit of the available pasturage. 

 As a consequence, it was not necessary to begin feeding hay until 

 February 7, three weeks later than usual. To prevent undue con- 

 gestion, feeding was begun simultaneously at four points — two by the 

 Federal warden in the refuge, and two by the State, one at Peter- 

 sen's ranch to the north and the other at Leek's ranch to the south. 

 Feeding was continued at these points until March 28, when the 

 elk scattered in search of outside pasturage. Stormy weather dur 

 ing the first week of April brought many of the elk back to the feed- 

 ing grounds, where feeding was resumed from April 5 to 8. The 

 maximum number of elk at the feeding grounds at any one time was 

 estimated to be about 10,000 head, of which about 2,500 were calves. 

 Of the 560 tons of hay harvested on the refuge during the summer of 

 1917, about 440 tons were fed to the elk during the winter. The State 

 game officials of Wyoming continued their elk-feeding operations be- 

 gim in 1909 and fed about 450 tons of hay at the points named above. 



The losses of elk about the various feeding grounds during the 

 season aggregated 365 animals, of which 325 were calves. As usual, 

 many starving calves came from the foothills to the feeding grounds 

 in March, and a considerable number of them died. No accurate 

 data are available concerning the losses on the winter ranges out- 

 side the refuge, but it is estimated they were far less than during the 

 preceding year. 



In order to lessen the losses on the refuge, a feeding corral con- 

 taining 5 acres was constructed near the headquarters in the fall, 

 mainly from material provided by State game officials, in order to 



