Mineral oil coating on raven eggs boosts sage-grouse nesting success

Scientists examined the impact of a non-lethal egg-oiling method on common raven reproduction in western North America. By sealing raven eggs with mineral oil, embryos die while the adults continue incubating, causing them to produce additional clutches that are also treated. Field trials revealed a sharp decline in local raven densities and a more than two-fold rise in sage-grouse nest survival, with sage-grouse numbers climbing 44% relative to control areas.

Lead author Steven Mathews-Sanchez, working with the US Geological Survey Western Ecological Research Center, cautioned that the approach alone cannot solve the broader issue of raven population growth driven by human waste, roads, and structures. He emphasized that protecting and restoring sagebrush habitat remains essential for the long-term viability of the greater sage-grouse.