Influence of Domestic Livestock Grazing on

20 In a pilot study, I observed a relationship between domestic livestock grazing and location of 21 American pika (Ochotona princeps) haypiles in the eastern Sierra Nevada and several Great 22 Basin mountain ranges. Where vegetation communities adjacent to talus bases (forefields) were 23 grazed, mean distance from talus borders to closest fresh haypiles was 30.1 m (SD = 18.9 m, n = 24 27), and haypiles were found only high in the talus. In ungrazed forefields, mean distance was 25 1.8 m (SD = 0.9 m, n = 57), and haypiles were found along the low-elevation talus/vegetation 26 border. Where grazing was active, haypiles consistently comprised vegetation gathered from 27 plants growing within the talus. These appeared to be of lower diversity and species of lower 28 nutritional value than forefield plants, a situation that, if true, would compromise quality of 29 forage for summer browsing and for winter haypile storage. This, combined with potentially less 30 favorable summer and winter thermal conditions of upper talus locations relative to lower talus 31 borders, suggests that grazing might be a factor compromising population conditions and status 32 for pikas. Recent studies have observed higher population extirpation of pikas in Great Basin 33 ranges (primarily NV) than in adjacent regions. Because domestic livestock grazing is widely 34 permitted on public lands throughout pika habitat in the Great Basin, but not permitted (or much 35 less) in pika habitat of the Sierra Nevada, CA, grazing effects might be contributing to observed 36 regional differences in viability of pikas. 37