BIOLOGICAL SUEVEY. 235 



the average cost of distributing poison on infested areas has been 

 less than 5 cents per acre and repoisoning operations have not 

 exceeded a cost of 3 cents per acre. 



GROUND SQUIRRELS ON NATIONAL FORESTS. 



In the California, Monterey, Sequoia, Kern, and Modoc National 

 Forests of California, the Toiyabe Forest of Nevada, and Sopris 

 Forest of Colorado work in controlling ground squirrels was carried 

 on, and experimental work was conducted on the Columbia ground 

 squirrel in Idaho. Cooperative work with the North Dakota Agri- 

 cultural College has resulted in perfecting methods for the control 

 of the Eicharclson ground squirrel, which has long been a costly pest 

 to grain growers of North Dakota. Very successful demonstrations 

 were made in many parts of the State. 



EXPERIMENTS AND DEMONSTRATIONS IN DESTROYING WOLVES. 



Demonstrations and experiments were carried on in Colorado, 

 Nevada, Texas, Idaho, Oregon, and other of the Western States with 

 a view to the control of wolves and coyotes. In eastern Oregon and 

 northern Nevada, where rabies prevails among coyotes, careful study 

 was made of the conditions, and a considerable number of hunters 

 employed to assist in destroying the coyotes with a view to eradi- 

 cating the disease. In this work the bureau cooperated with the State 

 authorities of Oregon. The results are encouraging, and of late no 

 new cases of rabies have been reported, and there is a very noticeable 

 .decrease in the number of coyotes. Demonstrations in Texas were 

 very effective, and many dens were discovered and the young animals 

 destroyed. Future work contemplates much extended activity and 

 the division of the area inhabited by wolves and coyotes into districts, 

 each in charge of a competent inspector, who will supervise closely 

 the operations of trappers and hunters. 



POCKET GOPHERS. 



Experiments in the Ochoco Forest of Oregon demonstrated the 

 practicability of exterminating pocket gophers in National Forests. 

 Campaigns were carried on in a number of localities within the area 

 inhabited by these animals. 



JACK RABBITS. 



Demonstrations were carried on during the winter in Oregon, 

 Washington, Idaho, California, Nevada, and Texas against jack 

 rabbits, which were devastating the 3'oung orchards and forage crops, 

 and many thousands of rabbits were destroyed. 



MOLES. 



During the year an assistant of the bureau has made extensive 

 studies of the life history of the mole inhabiting the Northwest, 

 where moles are so abundant as to be seriously destructive in meadows 



