Golden eagles in the Mojave Desert fly much farther and have a much larger range of habitat than previously known, according to a new study that suggests federal land managers should factor this into a sweeping plan designed to guide renewable energy across the Southern California desert.
The latest study, published this month in the journal Biological Conservation, used radio telemetry and global positioning system devices to track the year-round movements of eagles in the Mojave Desert in California.
The goal of the study, led by researchers at West Virginia University, was to get an idea about the distance “at which eagles may encounter renewable energy projects” within the 22.5-million-acre Desert Renewable Energy Conservation Plan (DRECP) area.
The Interior Department and state of California last fall unveiled the draft DRECP, which took five years to develop and is meant to guide commercial-scale solar, wind and geothermal power projects across public and private lands in the Mojave and Colorado deserts.
“Golden eagles in the Mojave Desert used more space and a wider range of habitat types than expected and renewable energy projects could affect a larger section of the regional population than was previously thought,” the study says.
Among the various conservation measures in the draft plan is a proposal adopting buffers around identified golden eagle nests.
Results of the latest study, however, indicate that the proposed buffers might need to be much larger than originally thought, said Todd Katzner, a U.S. Geological Survey wildlife biologist and one of the authors of the study, who also included researchers with the Forest Service and the Bureau of Land Management, which funded the study.
“Conservation measures outlined in the DRECP focus on protecting golden eagle nests by creating a narrow buffer around the nest,” Katzner said. “This study shows eagle habitat use is complex and often extends to areas beyond the DRECP conservation buffer. Managers planning for DRECP’s adaptive approaches to habitat conservation may wish to consider the desert golden eagles’ seasonal changes in behavior and reliance on habitat outside the DRECP boundary.”
The timing in golden eagle movements likely coincides with the eagles’ “breeding ecology and the seasonal variation in weather and prey availability,” according to a USGS summary of the study.
Among other things, the study found that golden eagles in the Mojave Desert move during summer months “to cooler, prey-dense, mountainous areas characterized by forest, grasslands, and scrublands.”
The study, which was able to document golden eagle movements in the desert with a higher level of accuracy than ever before, should provide land managers “with a better understanding of how the small population of golden eagles breeding in the Mojave Desert may be exposed to risk from renewable energy development in the area,” said Melissa Braham, a West Virginia University biologist and the lead author of the study.
The impact to eagles of the growing renewable energy industry, particularly large-scale wind power development, has been a source of controversy for several years.
The Fish and Wildlife Service drew the ire of conservationists in 2013 when it moved to allow wind farms and other industrial developments to apply for 30-year incidental take permits for eagles, which are protected under the Bald and Golden Eagle Protection Act. The American Bird Conservancy has filed a federal lawsuit challenging the eagle-take rule.
Fish and Wildlife in February announced it is considering establishing a permitting system that would allow the legal, unintentional killing of the more than 1,000 bird species protected under the Migratory Bird Treaty Act (Greenwire, Feb. 13).
The DRECP planning area is projected by Interior to see as much as 20,000 megawatts of commercial-scale development by 2040.
The draft plan calls for FWS to develop a “General Conservation Plan” that would allow the service to streamline the permitting process for renewable energy projects on non-federal lands in the planning area, including incidental take permits involving endangered or threatened species for renewable energy or transmission projects as long as the project backers agree to the conditions outlined in the DRECP.
Katzner said he hopes the latest study will help “provide a framework to evaluate the risk that wildlife populations face from development in general, and of renewable energy, across these biologically important desert habitats.”
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