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1950-1979

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https://hdl.handle.net/10217/100535

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Browsing 1950-1979 by Subject "Bighorn sheep -- Ecology -- Yellowstone National Park"

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    Summer ecology of bighorn sheep in Yellowstone National Park
    (Colorado State University. Libraries, 1968) Woolf, Alan, author
    A study of the summer ecology of bighorn sheep was conducted in Yellowstone National Park, Wyoming, from June 1966 to September 1967. Study objectives were to census the bighorn population, map the summer distribution, determine summer herd structure and behavior, observe daily feeding habits, and determine the effects of competition on summer ranges. The minimum number of bighorn summering in Yellowstone Park is 558. There were seven main summer herds: the NE herd, the lower Yellowstone and North park herd, the Washburn-Canyon-Specimen herd, the Gallatin herd, the NW herd, the East boundary herd, and the Bechler herd. Most summer range was in the northeast part of Yellowstone Park. Migrations to summer ranges was incomplete in some cases, and the sheep displayed tolerance for a variety of summer habitats. Ewe herd (includes yearlings):lamb ratios were 100:59 in 1966 and 100:48 in 1967. The 1967 ewe:yearling ratio of 100:28 indicated favorable yearling survival from 1966. Grasses, grass-like plants, and forbs formed the bulk of the summer diet. Carex hepburnii was the dominant plant on subalpine summer ranges and was the staple food throughout the summer. In one study site, grasses made up 80.9 and forbs 19.1 per cent of the diet. Interspecific competition was negligible during the study, but potential competition exists between bighorn and elk for space. The greatest potential danger on summer ranges may be intraspecific competition resulting in reduced tolerance to diseases and parasites.