Hailed as ‘clean’ energy, wind energy is seen as an affordable solution to satiate the ever-growing global energy demands. However, a new study by researchers at the Indian Institute of Science (IISc), Bengaluru, claims that wind turbines, installed to harness renewable energy from the wind, are instead creating deleterious effects on predatory birds and their prey. The study, published in the journal Nature Ecology & Evolution, has described how anthropogenic disturbances act as apex predators and how they affect the ecosystem of the Western Ghats.
The study was conducted in the lateritic plateaus of the Western Ghats of India where wind turbines have been functioning for the last 16–20 years. The researchers studied the behaviour of predatory birds and their prey, the superb Fan-throated lizard (Sarada superba)—the most common lizard species in the region. They compared the activities of these birds and lizards in areas with and without wind turbines on the same plateau.
The researchers found that wind turbines leads to many deaths of birds and bats, and restrict their movements. “We found that both the abundance of predatory birds and the frequency of predation attempts (dive attacks) by raptors on ground-dwelling prey were almost four times lower in sites with wind turbines”, say the authors about their findings.
The lack of predators has resulted in a rise in the number of lizards. The density of the superb Fan-throated lizards in sites with wind turbines was found to be three times higher than regions without those turbines. “By reducing the activity of predatory birds in the area, wind turbines effectively create a predation-free environment that causes a cascade of effects on a lower trophic level”, explain the researchers on the effect of wind turbines on the food chain.
The researchers also point out the direct and indirect consequences of the killing of the predatory birds by the wind turbines. Apart from the increase in the lizard density, the changes in the predation pressure have caused a reduction in the amount of the stress hormone, corticosterone, in the lizards.
“Changing predation pressure can affect the local density of prey through direct consumption, but predation risk can also cause non-consumptive effects by altering the behaviour, physiology, and morphology of prey that survives”, remark the authors.
Although the lizards in areas with wind turbines led a stress-free life, all was not well in the absence of their predators. One would expect the lizards to be healthy as they can now freely roam around collecting enough food without the fear of being eaten. However, the researchers found that the lizards were thinner in areas with wind turbines. The researchers explain that the increased density of the lizards, in the absence of their predators, could have lead to an enhanced competition for resources, resulting in the lizards being thin. The increased density also led to the reduction in sexual ornamentation or colouration in the male lizards, the study found.
The study emphasises the need for a thorough analysis of the consequences of such anthropogenic activities in ecologically sensitive areas.
“Since the locations of wind farms are mainly determined based on economic rather than environmental considerations, we stress that the consequences of wind farms are greatly underestimated. There is thus a strong need for an ecosystem-wide view when aligning green-energy goals with environment protection”, conclude the researchers.