CORVALLIS, Ore. — Greater sage-grouse nests found in natural gas development areas where mitigation actions were taken to minimize development impacts had slightly higher nest survival than similar areas where such actions were not taken, according to research by U.S. Geological Survey and others.
This site-scale study, conducted in a coal-bed methane area of the Powder River Basin in Wyoming, showed that enhanced mitigation efforts somewhat increased the probability of at least one sage-grouse egg hatching per nest in a particular nesting season.
Mitigation techniques are actions taken to avoid, minimize or offset the impacts of human activities on an ecosystem or a species, such as minimizing sagebrush removal and using remote monitoring of wells to reduce vehicle traffic.
The article, co-authored by the Big Horn Environmental Consultants, Boise State University, and USGS and published in the journal Wildlife Biology, looks at the application of science-based on-site mitigation techniques and sage-grouse nest survival in the Intermountain West.
“High nest survival is critical to the species’ continued existence,” said USGS emeritus scientist and co-author Dr. Mark Fuller. “These are ground-nesting birds that produce on average 6-10 eggs each year. Their nests are vulnerable to predation and other factors, making it difficult for the greater sage-grouse populations to maintain numbers.”
From 2008 to 2011, scientists monitored 296 greater sage-grouse nests in a coal-bed methane development where Anadarko Petroleum Corporation, in cooperation with the Bureau of Land Management, applied mitigation measures above and beyond base mitigation measures to determine if these measures would reduce negative impacts to greater sage-grouse. The base mitigation measures are required by the BLM in its 2003 Environmental Impact Statement for the Powder River Basin.
Over a 362-square-mile area, researchers measured nest survival in areas where the enhanced mitigation measures were applied, areas where only base techniques were used and in relatively unaltered areas without oil and gas development. Nest survival was determined by the evidence of at least one successfully hatched egg per nest, a standard measurement in avian scientific studies. Multiple studies have shown that poor nest survival rates can dramatically limit population growth in sage-grouse. Key findings include:
- Estimated nest survival rates were highest in unaltered areas with no oil or gas development (64 percent), next highest in areas where enhanced mitigation techniques were used (59 percent), and lowest in areas where base mitigation practices were used (54 percent).
- Of the mitigation measures implemented, piping discharge water to a treatment facility instead of constructing an on-site reservoir for produced waters had the greatest positive benefit on sage-grouse nest survival. Retention reservoirs result in direct habitat loss, may facilitate the spread of sage-grouse predators, and increase habitat for mosquitoes carrying the West Nile virus, thus expanding sage-grouse exposure to this disease.
- Reducing surface disturbance, particularly sagebrush removal, was also an important factor in nest success. The importance of sagebrush cover to sage-grouse nest survival is well known.
“In asking the question, does on-site mitigation reduce impacts of development on greater sage-grouse, we found that properly targeted mitigation can benefit greater sage-grouse nest survival in energy development areas,” said Chris Kirol, a research biologist with Big Horn Environmental Consultants and lead author of the study. “However, we also found that nests located in areas outside of energy development had the highest survival rates. Our results can help inform future adaptive management and greater sage-grouse conservation efforts in sagebrush habitat affected by energy development.”
Sagebrush habitat is increasingly being developed for oil and gas resources, and land managers face complex challenges in balancing energy demands with conservation measures for sagebrush-dependent species such as the greater sage-grouse. Agencies responsible for managing sagebrush habitat and greater sage-grouse populations encourage the use of adaptive management measures, such as science-based mitigation during oil and gas development and operations. Adaptive management is an approach for improving resource management by learning from and incorporating previous management outcomes into present plans.
Greater sage-grouse occur in parts of 11 U.S. states and 2 Canadian provinces in western North America. The U.S. Fish and Wildlife Service is formally reviewing the status of greater sage-grouse to determine if the species is warranted for listing under the Endangered Species Act.