Aspen Bibliography

Habitat shifts by mule deer: The influence of cattle grazing

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Journal of wildlife management





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We studied the effects of cattle on selection of home ranges and habitats by female mule deer (Odocoileus hemionus) on summer range in the Sierra Nevada, California. Three grazing levels (no grazing, moderate grazing, and heavy grazing) were imposed on 3 fenced range units over 3 years. Habitat selection by 13 radio-collared female mule deer was estimated each summer; habitat selection by radio-collared cattle was estimated at the 2 grazing levels. In the absence of grazing, meadow-riparian habitat comprised a greater proportion of deer home ranges than during grazing. During moderate and heavy grazing, a greater proportion of montane shrub habitat was included within deer home ranges than when ungrazed. Within home ranges, deer preferred meadow-riparian habitat at all grazing levels, whereas aspen (Populus tremuloides) habitat was preferred only during no grazing. Deer preference for meadow-riparian habitat declined over the summer, more so with cattle grazing. Cattle also preferred meadow-riparian and aspen habitats. The greatest effect of cattle on habitat selection by female mule deer occurred during late summer with heavy grazing when forage and cover were at a minimum in preferred habitats. Female mule deer shifted habitat use by reducing their use of habitats preferred by cattle and increasing their use of habitats avoided by cattle. These results were consistent with expectations of competition and habitat selection theory.