Responses of desert bighorn sheep to increased human recreation

Human recreation has been implicated in the decline of several populations of desert bighorn sheep (Ovis canadensis nelsoni). Managers are concerned a bout the impart of increased recreation on desert bighorn sheep in Canyonla nds National Park (NP), Utah, USA, where visitation increased 325% from 197 9 to 1994. We compared behavioral responses of sheep to recreational activi ty between a low visitor use area and a high visitor use area during 1993 a nd 1994 by observing behavioral responses, distances moved, and duration of responses to vehicles, mountain bikers, and humans on foot. Hikers caused the most severe responses in desert bighorn sheep (animals fled in 61% of e ncounters), followed by vehicles (17% fled) and mountain bikers (6% fled), apparently because hikers were more likely to be in unpredictable locations and often directly approached sheep. We observed considerable individual h eterogeneity in responses of bighorn sheep to the greater human use: some a nimals lived close to the road corridor and were apparently habituated to t he human activities, but other animals avoided the road corridor. In the hi gh-use area, we observed 3 radiocollared sheep that lived closer to the roa d than expected and found evidence of fewer responses to vehicles by female s in spring, less response time of all sheep to vehicles in spring, and few er responses to mountain bikers compared to the low-use area. Overall, ther e was an avoidance of tile road corridor by most other bighorn sheep in the high-use area where all animals, on average, were found 39% farther from r oads (490 +/- 19 m vs. 354 +/- 36 m) than in tile low-use area. This avoida nce of the road corridor by some animals represented 15% less use of potent ial suitable habitat in the high-use area over the low-use area. Increased sensitivity to hikers in the high-use area was suggested by a greater respo nsiveness by males in autumn and greater distance fled by females in spring . Responses of bighorn sheep were greater than human activity approached at tile same elevation, when sheep were moving or standing, when female inter actions occurred in spring and summer and male interactions occurred in aut umn, and when sheep were farther from escape terrain. We recommend managers confine hikers to designated trails during spring lambing and the autumn r ut in desert bighorn sheep habitat.