Eagles, falcons and other raptors make up to a third of the estimated 1500 birds killed each year at Australia’s biggest wind farm.
The finding of an independent report for Macarthur Wind Farm operator AGL follows 12 monthly searches of 48 turbines at the 140-turbine operation in Victoria that found 576 bird carcasses.
After adjusting for birds eaten by scavengers between searches and the total 140 turbines, Australian Ecological Research Services estimated each turbine killed about 10 birds a year.
The analysis said this would include 500 raptors a year.
AGL has confirmed that 64 bird fatalities were found during the official searches and an additional 10 carcasses were found near turbines by maintenance personnel, landowners or ecologists when not undertaking scheduled carcass searches.
The total included eight brown falcons, seven nankeen kestrels, six wedge-tailed eagles, one black falcon, two black-shouldered kites and one spotted harrier.
But an AGL spokesman said the report had “shown no significant impact on threatened species”. The company said overall estimates of bird and bat mortality “are subject to several sources of bias which may result in inaccurate estimates”.
The report recommended more frequent searches of a smaller number of turbines to get a more accurate assessment.
Australian Ecological Research Services said there were several reasons for the high percentage of raptors killed. They were at higher risk of collision with turbine blades possibly due to a combination of factors such as the altitude they mostly fly at, the proportion of time spent flying and flying behaviour.
“Raptors tend to glide slowly and are constantly looking downward for potential prey, rather than flying in a single direction and looking where they are heading,” the report said. “This may increase their risk of flying through the rotor-swept area of turbines.
“Other studies have also suggested that raptors are more likely to collide with turbine blades than many other avian species due to their morphology and foraging behaviour.”
Anti-windfarm campaigner Hamish Cumming said: “If someone shot this many birds they’d be fined and jailed and there would be public outrage.
“But, somehow, we’re expected to just accept it if they are killed by a wind farm.
“And before anyone rolls out the tired old mantra of ‘statistics show more birds get killed flying into suburban windows’, just tell me when was the last time a wedge-tailed eagle flew into your lounge room window?”