Department of Environmental Studies
The impacts of increased human visitation on desrt bighorn sheep (Ovis Canadensis nelsoni) were studied in the Island in the Sky District of Canyonlands National Park, Utah. Managers are concerned that increased exposure to human activity may adversely affect the health of the bighorn population and possibly lead to sheep mortalities. To determine how desert bighorn responded to increased amounts of human visitation, I compared the behavioral responses, distance fled, and duration of responses to human disturbance in two areas with higher and lower amounts of human activity. I examined the effects of environmental factors on bighorn response to a hiker and a vehicle using logistic regression techniques and compared the weight of each variable using Akaike Information Criteria (A.I.C.) I compared the effects of significant independent variables on bighorn response between and within study areas using Fisher exact and non-asymptotic chi-square tests. The results suggest that desert bighorns are habituating to vehicle traffic along the White Rim and Shafer trails, as evidenced by a decrease in frequency of overt responses and duration of responses. Additionally, though sample sizes were small, the results suggest that bighorn are also habituating to bicycle traffic. However, the results also show that the severity of bighorn responses to a hiker were not reduced by increased visitation, though there was a decrease in total response time. Behavioral responses to a hiker remained severe and sheep fled more often, fled farther and responded for a longer time that when disturbed by a vehicle or bicycle. Moreover, during the fall months, ram groups in the area with higher visitor use reacted more severely than those in the area with lower human use.