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Egg oiling offers a targeted way to reduce raven predation on vulnerable prey
Common ravens are intelligent omnivores that regularly consume the eggs and young of nesting birds, and their populations are boosted by human-provided food and nesting resources. This has resulted in elevated predation by ravens on many sensitive prey species, including greater sage-grouse.
A study in The Journal of Wildlife Management indicates that coating developing raven eggs with nontoxic mineral oil helps protect sensitive prey populations by reducing raven reproduction.
Investigators found that egg oiling—a management technique that stops the developing raven embryo from surviving without destroying the egg itself—reduces local raven numbers and improves nest survival and population growth of greater sage-grouse, one of the vulnerable prey species targeted by ravens.
"Applying egg oil to raven nests offers nesting sage-grouse some reprieve from nest predation. When raven nests were treated, sage-grouse nest survival more than doubled and relative abundances of sage-grouse increased by 44% compared with control populations," said lead author Steven Mathews-Sanchez, Ph.D., who conducted this work while at the U.S. Geological Survey Western Ecological Research Center and is currently a biologist for the San Diego Zoo Wildlife Alliance.
"Although highly effective at a local scale, egg oiling does not address the anthropogenic sources driving raven population growth, which must ultimately be addressed to protect sage-grouse and other sensitive species, nor does it address critical habitat required for sage-grouse to persist long term."
Publication details
Effects of Oiling Common Raven Nests on Ravens and Greater Sage-Grouse in Sagebrush Ecosystems, The Journal of Wildlife Management (2026). DOI: 10.1002/jwmg.70247
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Citation: Egg oiling offers a targeted way to reduce raven predation on vulnerable prey (2026, August 5) retrieved 5 August 2026 from https://phys.org/news/2026-08-egg-oiling-raven-predation-vulnerable.html
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