A new but preliminary birds study suggests lattice towers are indeed more dangerous for eagles and hawks. The pilot study, conducted in the Altamont Pass, found that all of the eagles tagged with transmitters that perched on wind turbines chose lattice towers. Red-tailed hawks were also found to be nine times as likely to use the lattice type, says the report, by the Predatory Bird Research Group at the University of California. "Circumstantial evidence suggests a relationship between perching and blade strikes," it says. In 1994, 57 eagles were tagged with transmitters, and another 46 were tagged in a study update. Of the ten that have died since the study began, two collided with turbines while the others collided with cars, were poisoned, were killed in fights with other eagles, or died from other causes. The study is seeking enough data to determine the impact of turbines on the area's entire eagle population. About 30 of the endangered birds die each year in the Altamont Pass.
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Senior Renewable Energy Analyst (WindGEMINI Product Lead) DNV GL Bristol (City Centre), City of Bristol