FOREST PLANTING IN" THE INTERMOUNTAIN REGION. 43 



Rabbits. — A special study of snowshoe-rabbit injury to plantations 

 and native conifers was made in this region, the results of which have 

 appeared elsewhere (1), Cottontail rabbits {Sylvilagus nuttalli) also 

 injure plantations, but less extensively than the snowshoe rabbits. 

 When plantations are examined and tree after tree is found nibbled, 

 eaten off, and dead, it is natural that failure should be charged to the 

 snowshoe rabbit without considering very carefully whether the plan- 

 tation would have succeeded if this injury had been avoided. The 

 true effect of these rodents can be determined only by comparing 

 results on protected and unprotected areas of the same site. Experi- 

 ments along this line have not yet been completed. Analysis of 

 results on plantations heavily attacked by the snowshoe rabbit, how- 

 ever, show that on favorable sites the death rate of trees attacked is 

 only a few per cent higher than of those which have been untouched. 

 On good sites the trees send out new shoots from adventitious buds 

 again and again with remarkable vigor, and given a few years respite 

 from the rodents, rapidly develop into good trees. 



As a direct cause of mortality, rabbits are not so dangerous as at 

 first appears, but they are one of the chief factors in retarding 

 development of plantations and in keeping the trees small and weak. 

 In new plantations the damage often occurs within a few days after 

 planting, regardless of the season, the rabbits apparently relishing 

 the novel food set out for them. In established plantations the 

 damage is more often found in the spring after a long snowy winter, 

 during which the rabbits found it difficult to secure sufficient food. 



Pocket gophers.— While rabbit damage is of most importance, 

 particularly throughout Utah and southern Idaho, pocket gophers 

 ( TJiomomys fuscipes) are most destructive in certain localities of some- 

 what limited extent. These animals, by destroying and feeding upon 

 the roots while burrowing underground, by covering small plants 

 with mounds of soil successively thrown up at intervals of 5 to 10 

 feet, and by leaving burrows in which the air can circulate freely 

 and dry the soil excessively, may entirely annihilate a plantation in 

 a short time. They are found at practically all elevations and are 

 active throughout the year, but do the most damage in winter, 

 when they pack the soil in their runways between the snow and the 

 surface of the ground. They appear less active in the spring than 

 in the summer and fall. Gophers are more common on flats and in 

 deep fine soil than on slopes or in rough stony soil. Plantations 

 should never be established on areas where these rodents are common. 



Ground squirrels. — The ground squirrel (Citellus columbianus) , 

 while less injurious than the pocket gopher, nevertheless injures 

 plantations by burrowing alongside the trees, by covering them 

 with soil, or by causing the roots to dry out. They also occasionally 

 defoliate the trees and cut off the stems. Trapping with No. O or 

 No. L steel traps is effective with both "burrow and. " surface" 

 sets, but this method of control is not sufficiently rapid on large 

 areas or where they are very abundant. Poisoning is the most 

 effective method of control. 



Rodents are undoubtedly credited with a greater amount of 

 damage than they are actually responsible for, since in many cases 

 dryness of the site alone would have caused these losses. Systematic 

 trapping is practicable, but poisoning is the best means of combating 



