DALLES POCKET GOPHER 33 



In the study described here, the grazed plot of meadow B had a 

 capacity of 6.10 sheep months per acre greater in 1948 than in 1940, 

 primarily as a result of gopher control. For purposes of comparison, the 

 value on a rental basis of the additional forage produced can be placed 

 at 17 cents per sheep month. On this basis the value of the forage pro- 

 duced by the grazed plot was $1.04 greater per acre in 1948 than in 1940. 

 A similar comparison between 1940 and 1947, the latter being an un- 

 favorable year for forage production, shows the value of the forage pro- 

 duced in 1947 to be 33 cents per acre greater. While the increase in 

 forage value due to gopher control was slow, the estimated cost of con- 

 trol measures was amortized within a few years. Beginning with the fifth 

 year of this study, the value of the increased grazing capacity for any 

 one year was equal to or greater than the estimated cost of control. 



SUMMARY 



Pocket gophers are scattered throughout western range lands, and are 

 abundant in many places. They are especially common on the mountain 

 meadows of the West, where range values vary from 0.1 or less animal- 

 unit month per acre to 2 or more animal-unit months. To determine 

 the value of pocket gopher control as a range-improvement practice, the 

 Fish and Wildlife Service and the Forest Service conducted a 17-year 

 study of the Dalles pocket gopher, its life history, and influence on plant 

 composition and grazing values on mountain meadows. 



The study area was on two adjacent mountain meadows (meadows A 

 and B) in the Blue Mountains of eastern Oregon. At the beginning of 

 the study both meadows were in poor range condition, with a sparse 

 vegetation composed principally of perennial forbs, and Dalles pocket 

 gophers were relatively abundant. Meadow A was freed of gophers and 

 kept free from 1931 to 1940, while gophers were allowed to remain on 

 meadow B. Then in 1940 the treatments were reversed, the gophers 

 being trapped out of meadow B and introduced onto meadow A at the 

 rate of 16 per acre. This situation was maintained through 1948. Two 

 quarter-acre plots were established on each meadow for detailed study, 

 one of each pair being open to sheep and deer grazing and the other 

 closed to such grazing. 



The following observations on the life history of the Dalles pocket 

 gopher were obtained from the study: 



1. It prefers open areas and is most abundant in mountain meadows. 

 It avoids dense forests, but gradually spreads into them as the canopies 

 are thinned by logging. 



2. Although it is active throughout the year, its activities are more 

 easily observed in the fall, when fresh soil mounds are numerous and 

 the vegetation is grazed. Control measures are, therefore, applied more 

 easily at that time. 



3. It feeds mainly on roots and underground stems, and on surface 

 vegetation in the immediate vicinity of its opened side runways. It shows 

 a definite preference for some of the more common broadleaved herbs, 

 but also feeds on grasses, young pine, quaking aspen, and other trees. 



4. Of 97 fall-trapped gophers, only 26 were current year's young, 

 indicating that the general rate of increase is low for a rodent. 



