Migratory raptors, such as harriers, are avoiding areas dominated by wind farms in Tamil Nadu, indicate initial observations, as part of ongoing studies by the researchers of Ashoka Trust for Research in Ecology and The Environment (ATREE).
While avian mortality studies and bird diversity studies are being conducted in areas with wind farms, experts say that long-term assessments in different arid landscapes and grasslands is essential to plan how to mitigate the impact of windfarms on biodiversity.
Tamil Nadu is home to about 25 percent of India’s total wind energy capacity and remains an important part of India’s renewable energy target of 450 gigawatts by 2030.
In the windy village of Radhapuram, in the Tirunelveli district, Tamil Nadu, Aditya Ganesh, who works with the Ashoka Trust for Research in Ecology and The Environment (ATREE), is studying rodents as part of a harrier monitoring project. The researchers set the traps for rodents in grasslands, where the harriers roost, to understand the diet of the bird. Their initial observations suggest that migratory raptors (such as harriers) are avoiding areas dominated by windmills – they forage in the area with windmills but don’t roost there.
This is a critical observation because wind power is considered a clean energy source and has been the mainstay of India’s renewable power basket for years. In fact, the southern state of Tamil Nadu, with one of the largest onshore wind farms in the world, accounts for about 25 percent of India’s total installed wind power capacity of 40.12 gigawatts (GW). It is also home to one of the country’s oldest wind farms. The state is even planning to expand the wind farms in wind-rich regions and explore offshore wind technologies.
The impact of wind power projects on biodiversity, especially birds, is an ongoing discussion in India. A case in the Supreme Court of India, for example, is considering the impact of wind power projects on the population of birds, including the critically endangered Great Indian Bustard (GIB), in the sensitive areas of Gujarat and Rajasthan. In Tamil Nadu, as wind farms expand, it is crucial, note experts, for the state to address concerns about the biodiversity trade-offs while aggressively pursuing renewable energy targets.
A bird flies close to transmission lines and an array of wind turbines in Tamil Nadu. Photo by Priyanka Shankar/Mongabay.
While talking about his research in Radhapuram, ATREE’s Aditya Ganesh said it will help in understanding harrier behaviour. “Grasslands are unique ecosystems and species here are interdependent. Many species interact with each other. Harriers are birds of prey, and their pellets usually have undigested food material which may contain fur, hair, bones, feather or scales, depending on what they eat, which informs their diet. I study the Montagu’s harrier (Circus pygargus) and the pallid harrier (Circus macrourus). The other part of understanding their diet is sampling the prey itself. I’ve found rats, squirrel, gerbils, and mice so far,” he explained to Mongabay-India. The harriers and their numbers are therefore important to the food chain in this area.
T. Ganesh from ATREE, who spoke to Mongabay-India from the Agasthiyamalai Centre of ATREE near Kalakkad Mundanthurai Tiger Reserve, about 90 kilometres from Radhapuram, said that while they haven’t conducted a proper study yet, they have observed that migratory raptors (such as harriers) are clearly avoiding the areas with windmills.
“They forage in the areas where there are windmills, but they don’t roost there; and harriers are birds that are usually not generally affected by windmills. We have seen a decline in the number of harriers in the region. In the number of Madras hedgehogs also, we see a decline. Although they are also hunted and poached, irrespective of windmills, we need a proper study,” he said.
“Wind turbines are coming up in grasslands, scrublands, and farmlands. Grasslands and open ecosystems are one of the most threatened systems. Renewable energy projects choose these sites that are both important in terms of biodiversity and support many livelihoods,” he said, emphasising that they haven’t conducted any studies on other species yet but are sure of the impact of turbines on biodiversity.
The recently published sixth assessment report from Working Group II of the Intergovernmental Panel on Climate Change highlights the linkages between human-induced climate change and its impacts on the health of people, focusing strongly on interactions between climate and ecosystems, including their biodiversity. This points to what is also reiterated by experts – the challenge of climate change cannot be looked at as independent from biodiversity loss.
Resources and skillsets needed for biodiversity assessments
Experienced ecologists and researchers, that are studying the impact of wind farms on biodiversity, spend several hours under windmills looking for bird carcasses. This search, called the ‘carcass survey’, involves walking around wind farms in different patterns. When a carcass is found, the species, its age, sex, distance from wind turbines, and other necessary, available details are recorded. But this must be done fast and on a regular basis, as the numbers can be imperfect if the scavengers clear the carcass before the exercise is conducted. This carcass search is physically straining, but necessary because understanding the behaviour of birds, their response to wind turbines and the reasons for bird fatalities is critical for mitigating the impact of wind farms on biodiversity.
While the lack of biodiversity studies in windfarm-dominated regions becomes evident, the standardised procedures and skillsets needed to conduct these biodiversity assessments are also unclear, says independent ecologist Hopeland P., who is studying the biodiversity at Muppandal (one of Asia’s largest onshore wind farms), for Dohnavur Fellowship, an institution in Radhapuram that works in the areas of child development and education.
“Although I have not conducted a proper year-round study, I observed that the number of raptors was lesser in areas with wind turbines and more in areas without them. I noticed a high insect diversity and a proportionately lower insectivorous species in the region (Muppandal). Also, the water birds are very less in number. This shows the imbalance in the species,” Hopeland told Mongabay-India.
“Even environmentalists see wind farms as an option out of coal and praise it. But in European countries bird mortalities due to wind farms are recorded by the thousands. The reason why it is not recorded here is because we need specific skillsets to do carcass searches. There are two ways to watch a live bird – by their flying pattern and movement or shapes. But how do you look for a bird on the ground? What shape is one looking for? The field skills required for carcass surveys are very different. We don’t exactly know at what distance the bird could get dislodged. There is no standardised method for this,” he said.
Reiterating the need for detailed biodiversity assessments in the wind farm sites, he stressed that “people must ask hard questions about biodiversity in renewable energy projects.”
When Mongabay-India analysed the publicly available research papers in this discourse, it found that research related to biodiversity impacts of wind farms in Tamil Nadu was low in comparison to other parts of the country and the rest of the world. While studies about avian mortalities due to wind farms have been conducted in India, studies about other flora and fauna are largely missing. As India gears to meet the 450 GW non-fossil fuel targets by 2030, which includes 140 GW of wind and 280 GW of solar power projects, there is an urgent need for more biodiversity studies in the region.
In comparison to Tamil Nadu, Kachchh in Gujarat is another important area for wind and solar power projects. Bombay Natural History Society’s (BNHS) Ramesh Kumar Selvaraj has studied avian mortalities from wind farms in Kachchh in Gujarat. His paper published in 2019, states that a total of 47 bird carcasses belonging to at least 11 species in a period of three years were reported from Kachchh. The estimated annual bird mortality rate for Kachchh was 0.478 birds per turbine.
The paper also spotlighted the issue of displacement of birds from turbine areas, changes in the behaviour of birds due to turbine noise and habitat alteration. The researchers conducted 23 rounds of search in Kachchh and among the carcasses they found were Eurasian collared dove (Streptopelia decaocto), rock pigeon (Columba livia), cattle egret (Bubulcus ibis), the vulnerable dalmatian pelican (Pelecanus crispus) and the near-threatened painted stork (Mycteria leucocephala).
Asked what this means about the impact of wind farms on biodiversity, Selvaraj said, “There is a clear impact of wind turbines on the bird population. Our study compared the composition of birds in both areas with and without wind turbines. There was a clear difference in the composition, as the number of species in the areas without turbines were more.” He emphasised the need for more biodiversity assessments to be conducted in India, especially in certain states such as Tamil Nadu where research is low.
A panoramic view of a private wind farm in Mettu Pirancheri at Thoothukudi district, Tamil Nadu.Photo by Narayana Swamy Subbaraman/Mongabay.
Have the species adapted to the turbines?
During a visit to the districts of Tirunelveli, Thoothukudi and Kanniyakumari, when Mongabay-India asked the local people if they observed bird/bat collisions, some stated that they have seen collisions, but most of them stated that the birds have adapted to the turbines, as the turbines in the landscape have been present for more than two decades now.
They point to the brightly painted tips of the blades in the newly installed wind turbines, (as mandated by the environment ministry) and state that the paint makes the turbines more visible to birds, thereby reducing collision.
So, have some of the species in the landscape adapted to the presence of the turbines? And have interventions by the wind companies, such as painting the blades in bright orange and installing bird diverters, helped in reducing collision? Stating that many of the birds fly at the altitude of the wind turbines present in the Tirunelveli belt, Hopeland said that even if some of the birds have adapted to the turbines, they are using much more of their energy for their everyday activities.
Citing the example of a sparrow lark, he said: “Sparrow lark (Eremopterix griseus) males generally perform their mating or courtship dance at a certain height. Now with the presence of the windmill, the males use the top of the turbine as a benchmark to perform that dance, thereby using several times of the energy needed for this activity.”
He stated that the least cost path for birds, i.e., the energy needed to travel from point A to B, increases with obstacles such as wind turbines present in their path.
Same assessment for different species?
While carcass surveys in wind farms may be a suitable method to study the impact of turbines on birds, what is the methodology to conduct assessments for other species?
Some residents of Tirunelveli have seen peacocks colliding with transformers and dying. Although the peacocks don’t fly at the altitude of the blades of the turbines, local people note that they have seen them collide with transformers. It’s a “clumsy bird”, they point out.
“I’ve witnessed several birds getting struck by the blades of the turbines, including owls, mammals such as fruit bats, ibises, etc. I feel happy when a bird that finds it difficult to navigate through the wind farm somehow manages to escape the blades of the turbine,” said Maria Antony, a nature educator and ecologist from Panakudi, a village near Radhapuram. Panakudi has many wind turbines and there is a fruit bat roosting site at the Panakudi police station where hundreds of fruit bats rest during the day.
Jeremiah Rajanesan, from Dohnavur Fellowship in Radhapuram, said that the Fellowship’s land in Muppandal is a very important scrub jungle that they are trying to conserve. They have leased out nine parcels of land to a wind company and support wind energy, but are also concerned about the biodiversity in the region.
“Ancient Tamils classified land under five categories – kurinji (mountains), mullai (forests), marutham (croplands), neithal (seashore) and paalai (dry lands). We are trying to promote the conservation of mullai landscapes. The scrub jungles in Muppandal are very important to us and they contain many rare species – the sambar deer breed there and there is also the rusty spotted cat. Many insects there are endemic to the region. Therefore, conserving the biodiversity there and conducting assessments are important,” shares Rajanesan.
Mathivanan, a senior research associate from ATREE, adds, “In my interaction with some of the pastoralists from Tirunelveli, I understood that the invasive Lantana camara plant species is spreading in the regions with wind turbines. This has taken over other vegetation and grass and has led to difficulty in grazing for the animals, thereby impacting the livelihood of the pastoralists.”
Ecologist and researcher Brawin Kumar, studying the Madras hedgehog (Paraechinus nudiventris) in Tamil Nadu stresses on the need to study the biodiversity of arid landscapes and grasslands because of the plummeting numbers of hedgehogs in the state. “Hedgehogs were present in this landscape before humans. They are wild animals that face multiple threats like loss of habitat, poaching and trading. Their habitats are not wastelands, but important grasslands that need to be regularly assessed,” he told Mongabay-India.
Responding to the question about the methodology to conduct assessments for different species in a landscape, Kumar said, “It is important to conduct longer biodiversity assessments in each landscape during the right season. The assessments would vary according to species groups and landscapes, and also seasons. One type of assessment simply cannot aim to understand different species in a landscape.”
Kumar recommends that Environment Impact Assessments (EIAs) be conducted before and after setting up renewable energy projects to understand the impacts better.
Land is a finite resource. Studies have found that land use change triggers biodiversity decline, especially in grasslands. Before planning the upcoming wind farms, ecologists and researchers urge developers to look at biodiversity assessments as a tool to meet both climate and biodiversity goals.
To set up renewable energy projects and meet the country’s net-zero emission goals, India needs an area almost the size of Bihar and primarily consisting of open natural ecosystems. Renewable energy projects, specifically wind farms in the southern districts of Tamil Nadu, are located in these open natural ecosystems which are mostly arid lands and grasslands with rich biodiversity. Therefore, it becomes essential to understand the sensitive biodiversity present in these landscapes before installing wind turbines.
“We need to plan windfarms which have the lowest impact on biodiversity. If painting the blades in a bright colour works, all companies must be encouraged to do it. Vortex technologies (turbines without blades) and other inventions can be explored,” said Hopeland.
BNHS in collaboration with Birdlife International is creating a Bird Sensitivity Map for India. Explaining to Mongabay-India about the objective of this map, BNHS’s Selvaraj said, “this is an important, dynamic tool.”
“With the help of the map, if we select one area, we can see if the place is highly sensitive for birds. It is especially useful for setting up windfarms and transmission lines. Species that are prone to collision with wind turbines will be highlighted on this map. Potential Ramsar sites will be included too. This will be useful for the wind companies in choosing the areas with the least impact on birds,” Selvaraj told Mongabay-India. The researchers aim to get this map out by the end of 2022.
Mongabay-India reached out to the energy department of the Tamil Nadu government to understand the steps taken to assess or conserve biodiversity in windfarm dominated landscapes, but received no response. The story will be updated if a response is received.
Banner image: Tamil Nadu lacks biodiversity assessments in grasslands dominated by wind farms. Ecologists recommend more biodiversity studies in the state. Photo by Narayana Swamy Subbaraman/Mongabay.