D. BIGHORN SHEEP 



1) Introduction 



The Ural-Tweed bighorn sheep herd occupies the east face above 

 Lake Koocanusa and is one of the few remaining native bighorn sheep 

 populations in northwestern Montana (Anon. 1975), The historical 

 distribution of the population has been along the east face from 

 Cripple Horse Creek north to Pinkham Creek, and the Kootenai River 

 east to the top of the Pinkham divide (Brink 1941, Couey 1950, 

 Brown 1979). Bealey and West (1935) reported bighorns as far south 

 as Dunn Creek. During the mid-1 960 's sheep were observed swimming 

 the Kootenai River, at various locations along the west side of the 

 river, and moving north and south across the United States-Canada 

 border (U.S. Dep. of Agric. 1965a, 1966). 



This herd has historically received a high level of management 

 consideration. Currently bighorn sheep are ranked fifth in manage- 

 ment priority for Region One (northwestern Montana), Montana Depart- 

 ment of Fish, Wildlife and Parks (unpubl. files). Due to the current 

 population status of this herd increased management will be needed 

 to insure the existence of a native population. 



2) Seasonal Habitat Preference 



Areas preferred by the Ural-Tweed bighorn sheep are steep, 

 south- and west- facing terraces formed by a series of cliffs and 

 benches containing an open bunchgrass habitat type with a few 

 scattered ponderosa pine and Douglas-fir (Ensign 1937, Brink 1941, 

 Zajanc 1948, Brown 1979). From observations of radio-collared 

 sheep. Brown (1979) determined there were movements of bighorns 

 between seasonal preference areas. 



3) Population Status 



The history and population trend of this herd is presented in 

 Appendix D. The available information indicates this population 

 underwent steady population growth from the 1940 's until it stabi- 

 lized in the early 1960's at approximately 150-200 animals. At 

 this time the population suffered a catastrophic decline in numbers. 

 Brown (1979) estimated, at the time of his study, there were approx- 

 imately 25 bighorns remaining in this population. Tlie current 

 population estimate for this herd is still approximately 25 sheep 

 (G. Brown 1983, pers. commun.) indicating the population has appar- 

 ently stabilized at this low level. 



The population estimates presented in Appendix D and the 

 methodologies on which they v/ere based were examined. Actual field 

 observations, such as the three intensive studies (Ensign 1937, 

 Brink 1941, Brown 1979), were used to temper the less exact esti- 

 mates. Ihe harvest data from 1954 through 1972 were used to verify 

 the population estimates considered to be representative of the 



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