Study shows link between cattle grazing, ravens and greater sage-grouse
As a generalist species that can take advantage of ecosystem disturbances, raven numbers have tripled across the West in the last few decades, and a new study shows that they are almost fifty percent more likely to use sagebrush habitat if cattle are present.
And that’s not all — according to the research, published in Ecosphere, ravens will set up camp near greater sage-grouse breeding areas, where the big black birds prey on the eggs and chicks of the endangered sage-grouse. Since predation is the main cause of sage-grouse nest failure, the researchers suggest that reducing ravens access to food and water could help with sage-grouse conservation.
The study was done by U.S. Geological Survey and Idaho State University scientists who looked at the relationship between common ravens and livestock across about 400 square miles of sagebrush-steppe ecosystem in southeastern Idaho.
“Common ravens are a known predator of numerous species including the greater sage-grouse,” said lead author and USGS scientist Peter Coates. “This study provides information to help rangeland resource managers develop conservation actions that focus on increasing the reproductive success of greater sage-grouse,” Coates said.
For example, limiting raven access to livestock resources, such as water troughs, and adjusting the timing of livestock access to sage-grouse breeding areas during the spring, would likely reduce raven predation on sage-grouse eggs.”
Research findings include:
- The probability of raven occurrence increased by 45.8 percent in areas where cattle were present.
- Ravens preferentially selected areas near sage-grouse breeding grounds, called leks, especially at sites where cattle were present.
- Landscape characteristics also influenced raven occurrence. For example, ravens selected relatively open (fewer trees) low elevation areas, specifically those with cropland, wet meadow and urbanization.
The study was a partnership of the USGS, Idaho State University, and Idaho Department of Fish and Game. The journal article is available here. Additional project information can be found at the USGS Western Ecological Research Center website.