Predators are commonly believed to reduce greater sage-grouse populations and of most importance is timing of death. Nest loss to predators is most important when potential production of young and recruitment are seriously impacted. Lack of adequate nesting and brooding cover may account for high juvenile losses in many regions. Nest success is related to herbaceous cover near the nest site. Taller, more dense herbaceous cover apparently reduces nest predation and likely increases early brood survival. Although predators were the proximate factor influencing nest loss, the ultimate cause may relate to the vegetation available to nesting grouse. Tall, dense vegetation may provide visual, scent, and physical barriers between predators and nests of ground-nesting birds. Greater amounts of both tall grass and medium-height shrub cover were associated collectively with a lower probability of nest predation. In a series of Nevada studies, artificial nest predation experiments were conducted. Artificial nests experienced 100% mortality with the loss of 1,400 eggs in 200 simulated nests in two weeks in one study, 84% of the nests were destroyed in three days in another study, while just 3% of the nests were destroyed in 10 days in an area of significantly better cover.