- Long-running wind farms in the Western Ghats of India are starting to show their effects on the local wildlife.
- Avian predators are avoiding these farms while their terrestrial prey is freely multiplying.
- However, absence of predators isn’t working out well for the prey, either. There’s just not enough food to go around.
The plateau of Chalkewadi in the Satara district of Maharashtra is a wide and open landscape. “One can see for miles on end,” says Amod Zambre. In the wee hours of summer, especially after it has rained, the plateau erupts into life. There are brilliant blue flashes all over the rocky landscape, he says. “Like tiny sapphires glinting in the morning sun.”
These are, in fact, males of the ‘superb fan-throated lizard’ flagging their coloured dewlaps to court females or fight off rival males, says Zambre, a graduate student at the University of Minnesota, USA. “The light morning mist makes the whole experience even more surreal.”
And surreal it is. A large part of the landscape is covered with wind turbines. And that might be why there are so many lizards here. This is the conclusion of a study Zambre and colleagues published in Nature Ecology & Evolution in November 2018.
During 2012–2014, the team studied avian predators and their lizard prey on the Chalkewadi plateau, where wind farms have been operating for almost two decades. Birds of prey, such as buzzards, eagles and kites, are the key day-time predators on the plateau. Of the lizards they prey on, one species is common here and found nowhere else – the superb fan-throated lizard (Sarada superba). The researchers studied these species across six sites – three with and three without wind turbines.
The number of birds at sites with up to 15 wind turbines, they found, was one-fourth that on the sites with zero turbines. The birds’ foraging activity followed a similar pattern; they made fewer hunts where turbines stood tall.
As a direct result of this, lizard numbers in areas with turbines were three times that of turbine-free sites. But that’s not all. The biology and behaviour of these lizards have changed as well. On wind farms they were skinnier and bolder, and their dewlaps less bright.
The researchers think that increased competition for food could be making the lizards leaner. “The predation pressure is released in this environment,” says Maria Thaker, an assistant professor at the Indian Institute of Science in Bengaluru and author of the study. So, there are lots of lizards and each individual gets less, she says.
A lack of predation has also made the lizards lose their fear of predators. To study their fear response, the researchers approached the lizards and measured how close they could get. On wind farms, they could reach within a distance of 3m before the lizards took off. In contrast, on the pristine sites without farms, the lizards fled at 15m.
“Lizards in the wind turbine areas let us get really close, almost to a point that we could step on them, before they ran away,” says Thaker. “They were bolder.” These lizards also had lower stress levels, measured by the amount of the hormone corticosterone in their blood. In an environment they perceive as less dangerous, Thaker says, the lizards down-regulate their anti-predator and stress responses. How these changes would affect the species’ survival remains to be seen.
The superb fan-throated lizard is known only from the Chalkewadi plateau. Wind farms there seem to have affected what makes the species special in the first place – its colourful dewlap, which only the males possess. The dewlap of lizards living on wind farms was less bright.
Colour is extremely important for these lizards, says Thaker; they use it to communicate with each other. “Females pay attention to the orange and they ignore the blue; males pay attention to the blue and ignore the orange.” Males get these dazzling colours by eating insects that are rich in pigments such as carotenoids. It’s likely that due to more lizards on wind farms, fewer insects were available for males to develop and enrich their hues.
Dewlap colours accumulate over the breeding season (April to May or early-June if the rains are delayed), says V. Deepak, a post-doctoral researcher at the Natural History Museum in London, UK, who was not involved in the study. (Deepak was part of the team that discovered and described the species from Chalkewadi.) He suspects that the colours may not have accumulated fully when the lizards were studied, which would explain their lack of lustre.
Zambre (who had also contributed to the discovery) counters: “We restricted our colour measurements to a short sampling window of about a month around the peak breeding time.” This was when most males were out displaying. To account for changes happening during the peak season, his team alternated sampling between the sites with turbines and those without. The differences between individual lizards were accounted for by the sample size (153 males), he says.
Lizards in wind farms were indeed less bright, asserts Zambre, who was affiliated with the Indian Institute of Science at the time of study. The take-home message, he says, is that small, often overlooked, species like this lizard can tell us how ecosystems are responding to anthropogenic pressures. “I am all for green energy… [but] one needs to acknowledge that it’s not ecologically benign.”
Thaker says, “We shouldn’t put wind farms in areas that are sensitive or unique. And the Western Ghats couldn’t be more unique.” The Chalkewadi plateau (which lies in the northern Western Ghats) might look barren to the untrained eye but that’s deceiving, she says. When monsoon is in full swing, it has pools of water teeming with frogs, fishes and crabs. “If you don’t have an ecologist on the table, you wouldn’t know that.”
CITATION:
Thaker M., Zambre A. and Bhosale H. (2018). Wind farms have cascading impacts on ecosystems across trophic levels. Nature, Ecology & Evolution, vol. 2, 1854-1858.
Banner image: The behaviour and biology of fan-throated lizards has changed in areas with wind turbines. Photo by Abi Vanak.
