- Loss of spring range. 



- 4,987 acres of important spring range inundated by the 

 reservoir . 



- Qualitative loss estimate - high. 



6) Derivation of Loss Estimates 



The estimated loss of 685 mule deer, resulting from the inun- 

 dation of winter range was derived by multiplying the total inun- 

 dated winter range for mule deer (11,600 acres) by a density esti- 

 mate of 0.059 deer/acre (Zajanc 1948) (Table 2). Because the den- 

 sity estimate used was from a period of lower mule deer density, 

 the estimated loss was considered to be an absolute minimum loss 

 estinate . 



Construction of Highway 37 through the winter range produced a 

 loss of 580 acres of winter habitat (U.S. Dep. Army 1971b, 1971c). 

 The habitat loss was subdivided into two portions: 1) the area from 

 Ten-Mile Creek to Stonehill; and 2) the remainder of the highway 

 from Five-Mile Creek to the Lake Koocanusa bridge. The estimated 

 acreage lost in each section was calculated by multiplying the 

 miles of road in the segment by 26.7 acres per mile. The Ten-Mile 

 to Stonehill segment (432 acres) was multiplied by a density esti- 

 mate of 0.059 deer/acre (Zajanc 1948) to obtain a loss estimate of 

 26 mule deer. The remainder of the estimated loss of habitat (158 

 acres) was multiplied by a density estimate (0.029 deer/acre) which 

 was equal to one-half of the previous density estimate (0.059 

 deer/acre) to obtain a loss estimate of 5 mule deer. The lower 

 density estimate was used because of the lower number of mule deer 

 using this portion of the winter range (Brown 1983, pers. commun,). 

 A total estimate of 31 mule deer lost due to construction of High- 

 way 37 was obtained by adding the two previous estimates (26 and 5 

 mule deer). Losses due to collisions with vehicles traveling along 

 the highway were additional with 20-30 animals estimated to be 

 killed for each of the 10 years since the completion of the pro- 

 ject. U.S. Dep. Inter. (1965) estimated 1,800 mule deer within the 

 area of influence; however, there was no prediction of how many of 

 these individuals would be impacted by the project. 



An estimated 4,987 acres of mule deer spring range (1,583 

 acres of grasslands and 3,404 acres of sub-irrigated grasslands/hay 

 meadows) were inundated by the reservoir. The deer using these 

 habitats were displaced onto higher, more dormant spring ranges 

 having lower nutritional levels. This resulted in a reduced repro- 

 ductive rate; however, no population loss estimate could be made 

 directly with the available data, and emphasis was placed on the 

 loss of habitat. In addition to the 4,987 acres of grassland 

 habitats lost due to inundation, a portion of the riparian and 

 conifer habitats inundated by the project also provided areas of 

 early "green-up" as spring range. However, these acres were not 



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