BUREAU OF BIOLOGICAL SURVEY. * 341 



ing the past winter. AVhere these animals were proving seriously 

 destructive to alfalfa, cotton, hay, muskmelon, lettuce, grain, and 

 other crops they were killed in great numbers by means of organized 

 drives and the use of traps and poison. In 10 counties of Idaho 

 32,235 pounds of bait treated with 2,159 ounces of strychnine were 

 used 6n 312,350 acres of land. By poisoning and by drives, 640,050 

 jack rabbits, by actual count, were destroyed there. In 6 counties 

 of Washington 155,500 jack rabbits were reported killed by poison, 

 trap, and drive, 1,873 in one night by the use of 4 ounces of strych- 

 nine alkaloid dusted on 30 gallons oi sliced apples. In Oregon it is 

 estimated that 350,000 rabbits were killed in four counties where this 

 work was undertaken, 58,300 being actually counted as a result of 

 poisoning operations in the vicinity of Fort Rock. In three counties 

 of Texas. 35.060 jack rabbits were killed by drives and the use of 

 pens in which poisoned baits were placed after prebaiting at these 

 places with alfalfa or maize heads to get the animals accustomed to 

 feeding there. 



Damage to orchards, vineyards, and agricultural crops by cotton- 

 tail rabbits continued to be reported from many points throughout 

 the country, and instructions for the control of these animals have 

 been furnished. 



• 



JfEADOW MICE, PINE MICE, POCKET MICE, AND KANGAROO BATS. 



Although small in size, various kinds of native mice, under favor- 

 able conditions, become excessiveW abundant and do serious dam- 

 age in orchards, gardens, and truck farms. During the year meadow 

 mice appeared in destructive numbers in many of the important or- 

 chard sections of Idaho and Washington. Where this condition was 

 foreseen in time, the use of poisons recommended by the bureau pre- 

 vented serious damage, but in many localities where poisons were not 

 used the loss of trees was heavy. Investigations made through the 

 area infested by pine mice disclosed the fact that damage by these 

 small underground animals was very great and widespread, irrepa- 

 rable injury to orchards often being done when the ground was cov- 

 ered with snow. Losses of sweet potatoes, white potatoes, and other 

 root or tuber crops were also exceedingly heavy, and much damage to 

 flower bulbs was reported. Pocket mice were found to be destroying 

 as much as 3 bushels of grain an acre in two counties in the State of 

 Washington. The damage was done by eating the planted grain and 

 by cutting off the ripened heads at harvest time. Effective work 

 was done by poisoning these mice where tlieir abundance and destruc- 

 tiveness warranted. 



Considerable assistance has been given landowners in the control 

 of kangaroo rats, through demonstration of practical methods. 

 Where these animals are found in large numbers, as in the sandy 

 regions of the Southwest, they cut the grass and interfere materially 

 with natural reseeding of the range by destroying great quantities 

 of seed of the native forage grasses. Areas from 20 to 30 feet in 

 diameter about their burrows are often completely denuded of grass, 

 and where the rats are numerous the}' thus cause a reduction of 

 10 to 20 per cent in the carrying capacity of the range. They also 

 make raids on fields of sprouting grain, thus reducing the amount 

 and the value of the crop harvested. 



