E). Stelfox (1976) noted this same type of fire suppression and 

 resulting loss of bighorn sheep habitat due to advanced ecological 

 successic8i in the Athabasca Valley, Alberta, Canada between 1921 and 

 1953. 



CompleticHi of the Libby Dam project inundated approximately 

 4,350 acres of bighorn sheep crucial winter range and spring range. 

 This area provided winter forage during periods of adverse climatic 

 conditions when the sheep concentrated at the lower elevations due 

 to snow depths which prohibited movement within the higher ranges. 

 Possibly more importantly, this lower portion of the sheep range 

 provided highly nutritious spring forage for animals which had spent 

 the majority of the winter subsisting on dormant, dried vegetation. 

 The importance of these areas was probably greatest for ewes in the 

 late stages of pregnancy or lactating. Stelfox (1976:29) concluded: 



"Valley bottoms and low-elevation south-facing slopes are evi- 

 dently important to sheep in late pregnancy, and they influence 

 lamb production and survival because they are the first areas 

 to green-up and provide the high protein forage necessary 

 during late pregnancy and early lactation". 



Following the reasoning of Cowan and Geist (1971), Wishart (1978) 

 concluded ewes on poor nutritional diets and in a state of energy 

 drain were unable to pass sufficient nutrients to their offspring 

 reducing the lamb's chances for survival. Brown (1979) documented 

 the historical spring use of the Kootenai River floodplain by big- 

 horn sheep. Since its inundation the sheep have actually shown a 

 tendency to use higher, dormant ranges in the spring (Brown 1979). 

 With the loss of important "green-up" areas, the sheep have been 

 forced to use lower quality dormant vegetation for a longer period 

 of time than normal, resulting in a suspected reduction in physical 

 condition and reproductive success. 



Part of the Libby Dam project was the relocation of Highway 

 37. Formerly this highway was located along the west bank of the 

 Kootenai River with access along the east side limited to the use 

 of unimproved roads and trails. The Burlington Northern (Great 

 Northern) Railroad paralleled the river on the east side; however, 

 with the exception of a few sheep mortalities resulting from colli- 

 sions and due to a relatively low level of human disturbance, this 

 railroad probably had minimal impact on the sheep population. 



Highway 37 bisects the bighorn sheep range creating an island 

 of habitat between Lake Koocanusa and the highway. EXie to the 

 increased human disturbance, sheep use of this land is probably at a 

 level below its historical level. In a summary of various studies, 

 Ihorne et al. (1979) concluded stress due to human harassment 

 (active or passive) had a detrimental effect on bighorn sheep by 

 increasing the overall energy expenditure and reducing the chances 

 of survival and/or growth of lambs, ewes and young rams. It also 

 may have caused the animals to forage in areas of poorer guality 

 habitat. Horejsi (1976:154) stated: 



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