Date of Award:

1-1-1990

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Ecology

Advisor/Chair:

John A. Bissonette

Abstract

The effect of seasonal cattle grazing on a newly reintroduced

population of California bighorn sheep (Ovis canadensis californiana) in

Big Cottonwood Canyon, Idaho, was studied. The hypothesis that bighorn

sheep avoid cattle was tested. The issue of avoidance between bighorn

sheep and livestock is arguable. Some studies have found that bighorn

sheep avoid cattle while others have found no response of bighorn sheep

to cattle.

Evidence was found to document the avoidance of cattle by bighorn

sheep. The size of the bighorn's home range and core area decreased

with the movement of cattle into areas of high bighorn use. As cattle

were moved into bighorn core areas, sheep responded by relocating.

Bighorn sheep decreased their distance to escape terrain as cattle moved

closer. The level and location of human disturbance on the study area

did not have any effect on bighorn sheep movements or how sheep used the

habitat.

The severity of response observed is in marked contrast with the

response of established bighorn populations to cattle. I suggest that

newly reintroduced bighorn sheep are extremely sensitive to disturbance

as a result of relocation trauma. Sensitivity may diminish over time.

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