similar. The habitats impacted by the Forest Development Road were 

 therefore considered to be substitutive and were not included in 

 the final tabulation of the project impacts to the mule deer popu- 

 lation. 



Loss of spring habitat was a major impact to the mule deer 

 population. Important spring range consists primarily of grassland 

 types at low elevations which "green-up" earlier than surrounding 

 areas (1,583 acres of grasslands and 3,404 acres of sub-irrigated 

 grasslands/hay meadows). These "green-up" areas provide nutritious 

 forage which allows for recovery from the nutritional deficiency 

 existing during the late winter period (Mautz 1978). This recovery 

 is necessary to insure healthy females prior to parturition and 

 lactation, resulting in a higher reproductive rate (Mautz 1978). 

 Loss of the spring ranges caused the deer to subsist on lower 

 nutritional ranges for longer periods, resulting in a lower repro- 

 ductive rate. In addition, the construction of Highway 37 bisected 

 the spring range, forming an island of habitat between the highway 

 and Lake Koocanusa, which prdbably receives less use due to in- 

 creased human activity. 



Ecological succession has also removed a portic8i of the winter 

 range available to mule deer. Establishment of the closed canopy 

 Douglas-fir communities onto previously more open Douglas-fir or 

 ponderosa pine communities has decreased the amount of browse 

 production and the total winter range available for mule deer. 

 Bergeson (1946) noted the big fires of 1898, 1910 and 1919 resulted 

 in increased availability of the food supply by reducing competi- 

 tion from mature conifers and then stimulating the growth of vari- 

 ous browse species. The fire suppression policy initiated by the 

 U.S. Forest Service in the 1930's circumvented the role of fire in 

 maintaining the disclimax community preferred by wintering mule 

 deer. 



5) Estimated Losses Due to the Project 



- Losses due to the reduction in the ability of the winter 

 range to support deer. 



- 685 mule deer lost due to inundation of habitat resulting 

 from formation of the reservoir (11,600 acres of winter 

 range) . 



- 31 mule deer lost due to construction of Highway 37 along 

 the east side of the reservoir (580 acres) . 



- Losses due to collisions with vehicles. 



- 200-300 mule deer lost during the 10 years since completion 

 of the highway. 



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