Paris (AFP) – Wind farms act as a "predator" in some ecosystems, damaging birds at the top of the food chain and triggering an indirect effect ignored by green energy advocates, scientists said on Monday.
Wind is the fastest growing renewable energy sector, supplying about 4% of global demand for electricity.
Nearly 17 million hectares – an area roughly the size of Tunisia – are currently used to generate wind energy around the world, and researchers warned that developers have greatly "underestimated" the impact of technology on wildlife.
In a new survey, an international team of scientists studied the effects of wind turbines on the Western Ghats, a mountain range and forest on the west coast of India and a global "focus" on biodiversity.
They found that predatory birds of prey were four times rarer in upland areas where wind turbines were present, a breakdown that cascaded down the food chain and radically altered the density and behavior of bird prey.
In particular, the team observed an explosion in the favorite meal of the raptors, throat lizards, in areas dominated by turbines.
In addition, they saw significant changes in the behavior and appearance of lizards, living as if they were in an essentially predator-free environment.
"What was remarkable for us was the subtle changes in the behavior, morphology and physiology of these lizards," Maria Thaker, an assistant professor at the Center for Ecological Sciences at the Indian Institute of Science and lead author of the study, told AFP.
As the levels of raptors fell around the turbines, so did the rate of predatory attacks that the lizards had to deal with.
As a result, the team found that the lizards that live in and around wind farms have lessened their vigilance against possible dangers.
By simulating "predator attacks," the humans in the study could be up to five times closer to a lizard in the wind farm zones than one who lived away from the turbines before the creatures ran away.
– "Be smart with green energy" –
After the tests, it was found that lizards near windmills had lower levels of stress hormone, something that must have come up in the two decades since wind farms were built in the Western Ghats.
Wind farms are known to be harmful to birds, disrupting their migration patterns and causing above-average mortality rates.
Thaker said his research, published in the journal Nature Ecology & Evolution, showed that wind farms replicated the role of the main predator in the food chain, keeping the raptors under control.
"They trigger changes in the balance of animals in an ecosystem as if they were the main predators," she said.
"They are the predators of the raptors – not in the sense of killing them but reducing the presence of raptors in those areas."
As man-made carbon emissions continue to rise, Thaker said that wind energy is vital in mitigating the effects of climate change.
But with the evidence that the impact of wind farms impacts more of Earth's ecosystems than previously thought, it called for more consideration of the environmental impact of the vital green energy source.
"It took decades for scientists to realize that wind turbines were negatively affecting the animals that were flying," Thaker said.
"We need to be smart about how we deploy green energy solutions. Let's reduce our presence on the planet and put turbines in places that are already disturbed in some way – in buildings, for example."