Emerging effects of energy-related infrastructure on greater sage-grouse nesting ecology
Energy-related infrastructure within sagebrush ecosystems can influence predator-prey dynamics and demography of species of conservation concern. Specifically, the growing number of transmission lines and other tall structures associated with increased demand for wind, solar, and geothermal energy activities may be contributing to increasing abundance of generalist predators that negatively influence population vital rates of their prey. Here, we present a synthesis of studies that describe direct and indirect effects of these landscape changes on predator-prey dynamics between common ravens (Corvus corax), an effective egg predator, and greater sage-grouse (Centrocercus urophasianus), a species of conservation concern in western North America. The individual studies were carried out over a 15-year period and consisted of extensive raven surveys within sagebrush ecosystems, radio-tracking of female sage-grouse at multiple study sites, and intensive nest monitoring of sage-grouse using video recording systems.
Our topics include: 1) common ravens identified as the most frequent predator of sage-grouse eggs: 2) sage-grouse nest survival decreases as a function of reduced microsite concealment and increased raven abundance; 3) ravens are most likely to depredate sage-grouse eggs immediately after the onset of the nesting season and risk of predation by ravens is minimal at later dates; 4) proximity to electric power lines and other energy structures, as well as the proportion of non-native vegetation, increases the probability of occurrence of ravens (territorial and non-territorial); and 5) preliminary analyses indicate a positive relationship between sage-grouse nest survival and distance to energy-related anthropogenic feature. Within sagebrush ecosystems, factors that contribute to the expansion of raven distribution and abundance may present an ongoing challenge for greater sage-grouse conservation and management. This information is preliminary and subject to revision. It is being provided to meet the need for timely best science.