Wind farms can serve as apex predators

Most birds have their predators, but there is one group of killers that murder our feathered friends, including predatory birds, with unmatched efficiency. And they do that without so much as trying.

We’re speaking of wind turbines.

It’s long been known that wind farms pose threats to birds, but new research indicates that these threats may be far more severe than generally assumed. A team of researchers from the Indian Institute of Science surveyed a wind farm in the Western Ghats region in India, a mountainous biodiversity hotspot recognized by UNESCO as a World Heritage site.

They found that avian raptors, like hawks and eagles, were four times less common in the area of the Chalkewadi Windmill Farms on a mountain plateau, which was converted into a wind farm two decades ago, than elsewhere. The reason: many raptors have ended up dead after flying into turbines. The birds may now be purposefully avoiding the area.

Yet even as predatory birds have been losers, some other species have been winners as a result of knock-on consequences. With most of the airborne apex predators gone, lizards at the wind farm have been proliferating. The absence of predators has caused lizard populations to balloon while local reptiles, such as fab-throated lizards, have lost almost all their sense of fear. “The cascading effects of wind turbines on lizards include changes in behaviour, physiology and morphology that reflect a combination of predator release and density-dependent competition,” the researchers explain.

Yet what may be beneficial to the lizards could be a disaster for the local ecosystem. “By adding an effective trophic level to the top of food webs, we find that wind farms have emerging impacts that are greatly underestimated,” the scientists elucidate. “There is thus a strong need for an ecosystem-wide view when aligning green-energy goals with environment protection.”

Several previous studies, conducted elsewhere, have played down the impact of windfarms on local avian populations. The benefits of wind farms, argued the authors of a study in 2009, for instance, far outweighed their drawbacks because climate change is a far bigger threat to wildlife than windfarms. “[W]ind farms and nuclear power stations are responsible each for between 0.3 and 0.4 fatalities per gigawatt-hour (GWh) of electricity while fossil-fuelled power stations are responsible for about 5.2 fatalities per GWh,” they wrote.

Be that as it may, future wind farms should be sited with appropriate care to ensure that as few birds as possible will fall victim to them, wildlife experts argue.