Wind farms considering detection systems to prevent bird deaths
MOJAVE — Just before daybreak, a group of naturalists don parkas to blunt the frosty wind blowing down a narrow canyon in the Tehachapi Mountains north of Los Angeles. They mount spotting scopes and cameras on tripods, and wait.
“Showtime,” one of them whispers at the first rays of light. The silence is broken by thousands of brightly colored birds the size of Christmas ornaments pouring north through the canyon on whooshing wings, just a few yards above ground.
Kern County bird expert Bob Barnes stands spellbound. Peering through binoculars, he says, “They’re following the contours of the canyon like a living river of birds.”
This is Butterbredt Spring, arguably the best place in California to witness the spring migration of birds. Why it attracts so many — tanagers, warblers, orioles, grosbeaks, vireos and flycatchers — is not entirely understood. But something about the topography and its fierce winds has a funneling effect on birds moving over the mountains along the Pacific flyway.
Throughout the Tehachapis, wild and windy places like this have become crucial refuges for songbirds, as well as for critically endangered California condors and federally protected golden eagles. They are also a magnet for wind farms spreading across the region’s cliffs, canyons and ridgelines.
Now, in what has become one of the most critical conservation issues in the state, wind farms are considering using radar units and experimental telemetry systems that they hope will avoid harming birds by identifying incoming species early enough to switch off the massive turbines and then — to minimize costs and maximize profits — turn them back on again as quickly as possible.
“The greatest threat to migrating birds in my lifetime is unfolding in those mountains,” said Jesse Grantham, former California condor coordinator for the U.S. Fish and Wildlife Service. “As for condors, strikes are inevitable. They travel together when a food source appears, so a single turbine blade could take out a lot of them in one swing.”
If that happens, a wind farm could face lawsuits, criminal charges and ample bad publicity.
“Renewable energy operators are coming around to the view that they have to do something,” said Gary Andrews, general manager and chief executive of De Tect Inc., a leading manufacturer of avian radar systems. If a protected species is killed at a wind farm that has a bird tracking system, prosecutors and others could conclude that the operator had done everything it could to prevent harm to wildlife, Andrews said.
Radar systems are expensive, with no guarantee they will perform. One problem is differentiating among avian species. Condors, for example, soar thousands of feet high while hunting for carrion. Golden eagles swoop fast and close to the ground. Migrating songbirds fly low in strong headwinds.
A standard De Tect avian radar unit sells for about $500,000 and works best in flat, uncluttered expanses devoid of trees and bushes that could overwhelm the telltale blip of, say, a condor. In mountainous terrain such as the Tehachapis, multiple radar units are recommended — some to look into valleys, others to look out of them. Additional “bells and whistles” include telescopic video attachments capable of discerning an eagle from a turkey vulture, Andrews said.
Avian radar systems are in operation at wind farms in Texas and in European nations including Spain. A radar unit was installed at Pattern Energy’s controversial Ocotillo Express Wind Project site in Imperial County. Pattern Energy declined to comment about its effectiveness.
Separately, the San Diego Zoo is developing a telemetry system to provide real-time data on the altitude and speed of every California condor outfitted with a transmitter. The system would automatically shut down turbines if a condor ventured within striking range.
Prospective customers for detection systems include the Los Angeles Department of Water and Power’s Pine Tree wind farm, about 100 miles north of Los Angeles, which is under federal investigation in connection with eight golden eagle carcasses found at the site over the last two years.
The DWP is developing an avian and bat protection plan to include measures for mitigating risks. Later this year, the agency plans to test a $3-million radar system designed to sweep the horizon, vertically and horizontally, for large birds, said Mark Sedlacek, director of environmental affairs for the DWP.
The DWP awaits necropsy reports that could determine whether Pine Tree will earn the dubious distinction of becoming the first wind farm in the United States to face criminal charges for killing eagles.
The agency initially reported that it believed turbines were responsible. However, it now says it should not have presumed a cause of death, raising the possibility that the eagles died in any number of ways, including at the hands of someone trying to discredit the facility.
Shawn Smallwood, an expert on raptor ecology at wind farms, said, “We know that birds die of all kinds of natural causes — but for eagles to die in those numbers is beyond the pale. I’ve been working with raptors since 1989 and I have never found a dead eagle outside of a wind farm.”
Pine Tree is adjacent to NextEra Energy’s North Sky River Project, which calls for 100 turbines across 12,781 acres of private lands.
A risk assessment of that project, which is within a mile of Butterbredt Spring, warned that condors spend considerable time soaring within the potential rotor-swept heights of the mega-turbines, which are more than 200 feet tall. A year ago, Fish and Wildlife detected two condors within three miles of the project and determined that it was likely that one of the birds flew directly over it. North Sky River is considering avian radar systems.
Environmental organizations led by the Sierra Club have sued the U.S. Bureau of Land Management for approving the right-of-way for the project. Of particular concern is the threat to condors, eagles and migrating birds that will pass through to and from Butterbredt Spring.
NextEra declined to comment.
Bird expert Barnes summed up the issues this way: “When there is no wind, turbines are switched off and birds fly high overhead. When the wind blows hard, birds flying into or out of Butterbredt Spring fly low. Connect the dots.”
The view from Sacramento
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