length decreases to 36-39 ni (120 feet to 130 feet) in August and remains rela- 

 tively constant through October. ^ 



Special Trapping Problems 



Problems With Trapping Schedule . A special problem involved the schedule 

 of snap-trapping. Since all habitat types Wcre not trapped concurrently but were 

 sampled in series, comparisons among them are confounded by the effect of pop- 

 ulation change through time. In other words, those areas sampled before breeding 

 began are likely to have smaller populations than those sampled later in the 

 breeding season regardless of any variable other than time. Therefore, comparisons 

 among snap-trapped areas must be made with caution. 



Problems With Short Duration of Study . The short duration of this study 

 detracts somewhat from the reliability and predictive applicability of the data 

 due to factors such as short-term climatic fluctuation, grazing schedule changes, 

 and periodic insect infestations. We hope that this source of error will be 

 compensated for by long-term monitoring, and that some reliability was gained by 

 sampling on both control and experimental plots within given vegetative associations. 



Problems With Cattle and Insect Foraging . No attempt was made during this 

 study to determine the impact of livestock or insect foraging on rodent sampling. 

 Consequently, the extent to which livestock and insect-related habitat modification 

 affected measured rodent population parameters is unknown. 



FURBEARERS 



Fur-bearing mammal species (as classified by the Montana Department of Fish 

 and Game, 1977) which were found in the study area are the muskrat, mink, bobcat, 

 and beaver (table 41). Other furbearers not so classified are the long-tailed 

 weasel, striped skunk, coyote, raccoon, badger, and red fox. While these species 

 are widely different in distribution, habitat preferences, and food habits, and by 

 no means represent a community, they are most conveniently discussed together, 

 since all are harvested for pelts. 



Recent estimates of fur harvest by licensed trappers in Fish & Game Region 

 6, which includes Liberty, Hill Blaine, Phillips, Valley, Daniels, Sheridan, 

 Roosevelt, Richland and McCone Counties, indicate that muskrat, beaver, coyote 

 and red fox are the most important furbearers of the region both in terms of total 

 number of pelts reported and the total market value of pelts. 



The mine study area apparently provides habitat for all furbearers mentioned 

 above; muskrat, striped skunk, coyote, and red fox were those most frequently seen 

 in the mine study area during this study, and are also those most frequently taken 

 in the area, according to local residents. A few beaver inhabit Nelson Creek and 

 its tributaries within the mine study area, but habitat here is considered marginal. 

 The bobcat is reported to be increasingly rare in the area; only one was observed 

 during the baseline study. 



184 



