Athayde Tonhasca Júnior has returned with an edifying text-and-photo essay on animals and wind turbines. His captions are indented, and you can enlarge the photos by clicking on them:
Ecofriendly hazards
In November 1883, Nature magazine informed its readers about The Vienna International Electric Exhibition, where electric motors, electric clocks, telegraphic equipment, telephones, railway signalling and other wonders of the modern world were to be presented to the public. One novelty was missed by Nature‘s correspondent: the windmill installed by the Austrian engineer Josef Friedländer (1836-1905) in the exhibition grounds. Friedländer’s contraption drove a dynamo that fed electricity into a series of batteries, which in turn powered electrical tools, lamps and a threshing machine. The little-known Austrian engineer is believed to have assembled the first ever engine that generated electricity from the wind (Bruyerre, 2022).
Poster advertising Vienna’s International Electrical Exhibition, 1883 © Wikimedia Commons:
Wind technology evolved rapidly since 1883, but it took the 1970s’ oil crisis for wind power to be considered a viable alternative or supplement to carbon-based energy sources. The first wind farm in the world, consisting of 20 turbines, was installed in the American state of New Hampshire in 1980. From then on, the wind industry never looked back. Wind now meets about 10% of US’s electricity needs and 20% of Europe’s, and demand around the world is growing rapidly. It’s no wonder. Wind is a renewable energy source, with a much smaller impact on the environment than fossil fuel alternatives: for one thing, wind turbines do not produce greenhouse gases.
The San Gorgonio Pass Wind Farm in California, USA, comprises 3,218 units © Ken Lund, Wikimedia Commons:
Alas, just like trusted and popular medications, diets and political choices, the planet’s thousands of wind turbines have side effects.
Volant creatures who venture into the path of massive blades rotating at high speeds can’t have bright life prospects. Indeed, wind turbines do kill many birds and bats. And one aspect of turbine maintenance suggests a considerably larger number of victims of other kinds. If rotor blades are not cleaned regularly, the turbine’s power output may drop by 25%. The culprits of this reduced performance are promptly identified on a stationary turbine: insects, thousands of them, who ended up splattered against the blades, interfering with their aerodynamics (Corten & Veldkamp, 2001).
(a) A blade cleaner in action, (b) insect detritus on a blade’s leading edge © Voigt, 2021:
Migrating insects are the most likely victims because they usually travel way above the flight boundary layer, which is the space above ground where regular activities such as feeding, mating and nesting take place. Seasonal migrants such as the monarch (Danaus plexippus) and painted lady (Vanessa cardui) butterflies, who travel long distances at high altitudes, are particularly vulnerable if turbines are installed along their routes. Other forms of translocations also increase insects’ exposure to the dangerous blades. Some species fly to a topographic summit such as the top of a hill to meet the opposite sex and mate. This phenomenon, known as hill-toping, is common among species of flies, butterflies, dragonflies, wasps and beetles that occur naturally at low densities. By flying to the same conspicuous meeting point, these insects don’t waste time and energy looking for sparsely scattered mates. Lamentably, hill tops are exactly the type of place suitable for wind turbines.
Typical wind turbine heights and worldwide power capacity since 1990. Turbine shapes are compared to insects’ flight boundary layer (FBL) and to the turbulent surface layer that insects attempt to overcome during migration © Thess & Lengsfeld, 2022:
Even though numbers vary widely depending on local conditions, wind turbines do dispatch many birds and bats. But the important question is: are the numbers killed large enough to make a difference? Cats, buildings and cars, in that order, kill far more birds than do wind turbines (Ritchie, 2024), but people and organisations who keep an eye on birds’ welfare don’t seem to rank those factors as main threats. As for insects, wind turbines wipe out quite a few of them, but it’s impossible to gauge impact without a measure of proportion. About 3.5 trillion insects (3,200 tons of biomass) migrate above southern Britain annually (Hu et al., 2016); for hoverflies alone, up to 4 billion of them (80 tons of biomass) travel from Europe to Britain every season (Wotton et al., 2019). In East China, ~9.3 trillion nocturnal insects (15,000 tons of biomass) migrate at heights of up to 1 km over a 600 km-wide area every year (Huang et al., 2024). Would wind turbines significantly dent those figures? Probably not. But we don’t know.
Death by collision may not be substantial, but that’s not the only concern about wind turbines. They have an indirect but sizable impact on mammals, birds of prey and other wildlife without killing them. Noise, vibration, blade rotation and flickering lights prompt some animals to move away from onshore windfarm areas (Tolvanen et al., 2023). Avoidance may have cascading effects; in India, the abundance and activity of predatory birds were reduced near a wind farm, resulting in increased densities of the superb large fan-throated lizard (Sarada superba) (Thaker et al., 2018).
The superb large fan-throated lizard is not a NIMBY. Areas with wind turbines had lower abundance of predatory birds, lower frequency of raptor attacks on ground-dwelling prey and higher densities of lizards © Rushikesh Deshmukh, Wikimedia Commons:
We know very little about indirect outcomes on insects. Nonetheless, we do know that wind turbines cause a range of local environmental disturbances such as artificial lights, noise, vibration and changes in temperature and wind patterns – all known to affect some insect species at different levels (Weschler & Tronstad, 2024, and references therein). Thus, it wouldn’t be reasonable to expect insects and other invertebrates to carry on unscathed by turbines.
Wind turbines influence the environment by mixing the air and increasing turbulence (a), changing humidity patterns (b), increasing carbon dioxide respiration (c), warming near-surface air temperatures at night (d), reducing wind speed at hub height (e), light pollution (f), audible noise (g), and infrasound (h) © Weschler & Tronstad, 2024:
Any impact of wind turbines on wildlife is going to become more severe just because there will be a lot more of them. Reaching the 20 C limit set up in the Paris Climate Agreement will require nearly complete shifting to low-carbon sources and renewable energy. If that’s to be done with wind and solar power, which are the leading instruments for offsetting fossil fuels, the world may have to dispose of over 11 million hectares of land to accommodate wind and solar farms (Kiesecker et al., 2019).
Wind is a clean, readily available and unlimited source of energy, so wind turbines – together with solar panels – are deemed essential for reducing emissions and mitigating the effects of climate change in the short run. Even still, we can’t gloss over their known and potential risks. By addressing these, we can find mitigation measures. This has been done for birds and bats: avoiding migration corridors and breeding spots, stopping blade rotation when bats and birds are most active, painting one blade black to make the rotating blades more visible, using acoustic deterrents and illuminating turbines with ultraviolet light or painting them purple are among the measures proposed – even though not all have been tested. Insects, who account for the bulk of the planet’s animal biodiversity and are crucial for so many ecological services, have been all but neglected in these investigations. That’s regrettable, as we are missing the opportunity of learning effective techniques to reduce the effects of a warmer planet in more biodiversity-friendly ways.
Wow – never thought of that – but yes, I’d agree – a complex estimation as well.
There are, of course, other ways to harness wind energy without the splatter, such as wind vibration generators, solid state wind generation, Flettner rotors, and so on.
Interesting thing, Flettner rotors.
I was looking up different wind turbine designs and found that there are several, with complex pros and cons about durability, efficiency, and animal kill factors. It looked like a two-bladed turbine had some edge, and the lower surface area means fewer animal kills, but the two blade design wears out a bit faster than three. Economics carries a lot of weight in deciding where the industry goes.
“… the world may have to dispose of over 11 million hectares of land to accommodate wind and solar farms (Kiesecker et al., 2019).”
This is about the same amount of land devoted to the production of fossil fuels. And “dispose” is not the best choice of words.
Wind and solar farms do not preclude farming taking place amongst the towers and panels. And solar farms appear to have significant benefit to native wildlife in many situations, including the potential to reverse desertification.
My G*D! But I do like lizards.
Excellent post. We all know that windmills impact wildlife, but your post tells me that a comprehensive book needs to be written on the topic. Maybe there already are books or symposium volumes on this important topic.
I’VE GOT IT :
Paint mosquito attractant on the blades.
Mosquitoes will overwhelm any other insects that might otherwise inadvertently hit the blades.
PROBLEM SOLVED 😆
Nice article. Could you please share the bibliography?
The importance of threats to birds depends strongly on the species. Large raptors and condors are especially vulnerable, because they are rare to begin with, they wander far, and they have a slow reproduction rate. On top of that, they may be attracted to open areas that have more lizards or rodents than normal. A loss of one or two raptors of a given species per year would be an important population sink with consequences for a much wider area than the property where the turbines are located.
Seabirds are also particularly vulnerable.
In my opinion, wind turbines are a serious ecological threat. Whether the negative impact is greater than the positive impact of reduced global warming is very hard to figure out. But no matter how that prioritization goes, I think we should work hard to try to find other alternatives rather than consider wind power one of the go-to solutions.