. Die kanadische Feld - naturforscher. 1971 Stelfox: Bighorn Schafe in Kanada 1800-1970 115 Ji^, - ich^^^^^. w. .'%Â â Abbildung 8. Elk Nahrungssuche auf Bighorn Schafe winter Range, Mt. Galwey, Waterton Lakes National Park, Februar 1967. Elk, haben die größten Wettbewerber für Futter auf Bighorn Schafe Winter reicht in den Nationalparks von 1940 wurden bis 1970., die in der Lage sind, nur eine sehr begrenzte Anzahl von Pflanzenwachstum unterstützt." Aber, Elch waren knapp auf kritischen Bighorn Schafe winter östlich von Jasper in der Coalbranch Gebietsbereiche während der 1940er Jahre (Stelfox 1964 a), und das Absterben können Plac getroffen haben

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. The Canadian field-naturalist. 1971 Stelfox: Bighorn Sheep in Canada 1800-1970 115 ji ^ , -i^^^^ ^.f. .'%â â Figure 8. Elk foraging on bighorn sheep winter range, Mt. Galwey, Waterton Lakes National Park, February 1967. Elk have been the greatest competitors for forage on bighorn sheep winter ranges in the National Parks from 1940 to 1970. that are capable of supporting only a very limited amount of plant growth." However, elk were scarce on critical bighorn sheep winter ranges east of Jasper in the Coalbranch region during the 1940's (Stelfox 1964a), and the die-off may have taken place when ranges were still productive. During the 1930's and 1940's, fire control caused coniferous forests in Jasper to encroach on grassland (Pfeiffer 1948). Regenerating forests were also evident on montane and sub- alpine grasslands east of Jasper (Stelfox 19646). Wolves, abundant in the Jasper region in the 1940's, were ineffective in controlling sheep populations (Cowan 19476). The winter range contained one wolf per 10 square miles com- pared with 30 to 40 wild ungulates per square mile, or 300 to 400 ungulates per wolf. From 1943 to 1946, ungulates made up 80% of the wolfs annual diet, of which elk alone comprised 47% and mule deer 15%; bighorns were sel- dom hunted by wolves (Cowan 19476). Pneumonia-lungworm disease and severe winter weather were therefore responsible for the five major die-offs during the period 1936 to 1950. Underlying these factors was detiora- tion of critical winter ranges by excessive ungu- late populations. 1950 to 1966 â A period of rapid increase An increase in numbers of sheep, earlier apparent in Waterton and Kootenay, became generally evident in all areas in the early 1950's. Populations rose slowly until 1955 then in- creased rapidly during the next decade. The increase was initially more rapid in the south, as during the 1915-35 build-up. In 1953, Ban- field (1953) estimated slightly more than 600 in Banff, slightly less than that in Jas

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