PREDATION OF ARTIFICIAL SAGE GROUSE NESTS IN TREATED AND UNTREATED SAGEBRUSH

We measured predation on 120 artificial Sage Grouse (Centrarcus uropha sianus) nests in montane sagebrush grassland in northern Utah. We exam ined nests in areas that had been chained and seeded 25 years previous ly (treated areas) and in areas that were untreated. Predation rates o f artificial nests were higher in areas of untreated sagebrush, even t hough these areas had greater sagebrush cover, taller shrubs, and grea ter horizontal plant cover. These results differ from those previously hypothesized for treated sagebrush habitat and may reflect a greater abundance of other potential prey species, especially lagomorphs, in u ntreated areas that attracted greater densities of predators. In addit ion, over 80% of nests were depredated by mammals, which hunt using ol faction and are less likely than avian predators to be affected by nes t cover. We conclude that, after treated sagebrush has recovered to so me degree, predation rates of Sage Grouse nests may be lower in treate d sagebrush. Consequently, factors other than nest predation (e.g., wi nter food, thermal cover, insects, perennial forb abundance) may be mo re important reasons for preserving mature sagebrush stands for Sage G rouse.