Influence of Cattle Stocking Rate on the Structural Profile of Deer Hiding Cover

Hiding cover available for California (Odocoileus hemionus californicus) and Rocky Mountain (O. h. hemionus) mule deer was monitored during summer under no, moderate, and heavy cattle stocking rates in quaking aspen (Populus tremuloides) and meadow-riparian habitats in the central Sierra Nevada, California. Use of willow (Salix spp.) and herbaceous vegetation in meadow-riparian habitat was also measured using exclosure plots. Hiding cover in aspen and corn lily (Veratrum californicum) vegetation types was not reduced through mid-season in ungrazed treatments but was significantly (P < 0.05) reduced under moderate and heavy grazing. Increases in cover of aspen understory were detected after 2 years of cattle exclusion. Willow vegetation was resilient to the impacts of cattle under moderate grazing, but hiding cover was significantly (P < 0.05) reduced with heavy stocking rates. Browsing of willows by deer was light in ungrazed treatments but increased as the season progressed in cattle-grazed areas and as stocking rate increased. Natural weathering was partly responsible for overall hiding cover lost during the summer but reductions prior to mid-summer were attributed to cattle. The high proportion of hiding cover lost early in the season coincided with the 1st 2 months of life for fawns.