30 



COMMON MAMMALS OF WESTERN MONTANA. 



They live principally on seeds, berries, and grain, and lay up quan- 

 tities of food for the winter. Owing to their abundance they destroy 

 considerable quantities of grain and berries, often carrying off and 

 storing more than they eat on the spot. (Fig. 21.) They do great 

 damage in nurseries and on forest sowing areas, where they dig up 

 and destroy the seeds, this damage being so serious that no sowing can 

 be successful where they are plentiful. 



They are frequent hosts of young wood ticks and are of especial 

 importance in fever districts because they frequently live in occupied 



houses and may thus be the means of 

 bringing infected ticks into contact 

 with man. 



POISONING WHITE-FOOTED MICE. 



In most localities white-footed mice 

 take poison readily and are easily killed 

 by any of the baits recommended foi 

 chipmunks or ground squirrels. (See 

 Formulas I to IV.) The poisoning 

 must be done, however, in the spring 

 or earl}' summer, for after the various 

 native seeds and berries ripen, the mice 

 begin to store away their winter food, 

 and poisoned baits are simply stored, 

 not eaten. Thus while 13 dead mice 

 li ne been found from a couple of dozen 

 poison baits placed early in the sum- 

 mer, 5 bushels of poisoned wheat have 

 been carried off by the animals in Octo- 

 ber without materially lessening their 

 numbers. It is therefore evident that, 

 though white-footed mice are easily killed in- the spring and early 

 summer, poisoning done after the native seeds and berries ripen is 

 likely to be wholly useless. 



HOUSE MICE. 



These little gray mice, with their long hairless tails and small ears, 

 are native to eastern Asia, but have been introduced by man into 

 most civilized parts of the world. In Montana they are abundant 

 in most of the large towns and are to be found on some of the out- 

 lying ranches. Although no ticks have been found on the few house 

 mice examined, it is probable that these animals do occasionally serve 

 as tick hosts, for they frequently live in infested fields. 



Though not quite so easily poisoned as the native mice, they may 

 usually be killed by either of the forms of poisoned grains recom- 



484 



Pro. 21. — White-footed mouse 

 killed by carrying 17 kernels 

 of poisoned wheat. 



