Do wind turbines impact wildlife?

Although wind turbines are providing huge benefits in terms of us getting more clean energy into the UK and around the world, on windy days at least, it's important to recognise that these are really huge, potentially intrusive structures. These turbines jut up hundreds of feet into the air. So what impact is that having on birds which normally fly through these paths? And for offshore wind farms, are they impacting life below the sea? Over to Chris Smith...

Chris - There are thought to be over 8,000 onshore and 2000 offshore turbines in the UK alone now, with numbers still rising. While the energy they generate will over time, of course, form part of our solution to the climate change problem, their immediate impacts on proposed construction sites do of course have to be taken into account...

Aedán - So we're not only in a climate emergency, we're in a nature emergency as well and wind turbines, wind farms -really good at generating low carbon energy, so that's really positive, but they do present some risks to birds and their habitats

Chris - That's Aedán Smith, he's head of policy and advocacy at RSPB Scotland. This danger was highlighted in one of the first wind farms in the United States in Altamont Pass, California...

Aedán - It's really important migratory route for lots of bird species, and lots and lots of birds were tragically killed by colliding with the turbines there as we were passing through

Chris - From this tragic incident, bird behaviours and habitats are now taken into account before a turbine is erected...

Aedán - Working with conservationists and with government agencies to avoid the most sensitive places for the most part. So that fortunately has meant we've not had too many of those really terrible situations like at Altamont pass.

Chris - Even though some may argue that more birds are killed by cars and cats in a year than turbines, particular species might be more vulnerable...

Aedán - There are not all that many Eagles for instance killed by domestic cats, but actually that is a sort of species that is potentially at risk from colliding with wind turbines

Chris - Wind turbines can disrupt bird populations in three ways with the first being...

Aedán - Collision. So collision with a moving turbine blades. The other thing is though that these structures are novel if you like, it's not something which wildlife has evolved to coexist with. So sometimes birds see a turbine and then go absolutely nowhere near it, which is great for avoiding colliding with this structure. But maybe if they avoid an important feeding area or nesting habitat, then that could have an impact on their ability to survive. And a third type of impact is more of a barrier effect. Birds often will nest or roost in a certain location and then go off to feed somewhere else; they're journeying, they're commuting, if you like. And if a wind turbine suddenly appears on that commuting route, they may need to avoid that. And if the bird is using up every last ounce of energy just to survive, and then suddenly it's got to take a longer route, that could maybe tip the balance and tip it over the edge

Chris - These factors are taken into account when sighting turbines to avoid disruption to populations, and we've now got years of data to help us to ensure that the sites on land are selected successfully. But when we look offshore, we don't have a similar body of data to fall back on yet. So it's much trickier to predict what sort of impacts these turbines are going to have on that wildlife. There's currently also a conflict between generating more green energy by erecting more offshore wind turbines, and trying to better understand - and ultimately protect - seabird populations...

Aedán - Fortunately, technology is helping us quite rapidly here. It's possible to put tags on seabirds and that's quite a recent development because the technology has got such that the tags have got small enough that they can fit on some of the smaller seabirds now. And that is really rapidly increasing our knowledge about where birds are going after they're leaving nest sites on the coast, and they're going out to feed out at sea, and also where they're going in the winter.

Chris - But the effects of these offshore wind turbines are not confined just to the air they spin through because scientists are increasingly documenting impacts in the underwater realm too, particularly for crustaceans like crabs and lobsters. Thanks to advances in tracking technology, we can now much better understand how these animals get about. Alastair Lyndon is a marine biologist at Heriot-Watt University, where he's been following the travails of the edible brown crab...

Alastair - Recent tagging work has suggested that they move over quite large distances, particularly the males. And it seems that they, generally speaking, move up the coast from the southeast to the north, and then from the north round the top of Scotland and down the west coast.

Chris - The female crabs, although not traveling as far, still move away from the coastline in order to brood their eggs and ensuring their numbers is vital...

Alastair - Crabs, in terms of volume and value, are the second most important crustacean catch in the UK, as far as fisheries are concerned. They're extremely important for small rural and isolated communities.

Chris - Increased numbers of offshore wind farms means inevitable changes to the surrounding marine environment, which could influence wildlife behaviour...

Alastair - It means that there'll be a lot more electrical cables around on the seabed compared to what there have been in the past. And the implication of that is that they generate a magnetic field around the cable, which can't be shielded. We know that a lot of marine organisms have - or at least we suspect have - magnetic senses, probably for navigation, using the earth magnetic field, which of course is very, very weak. So if they can detect the earth magnetic field that might interfere with any movements or migrations where they might be using that magnetic field for direction finding

Chris - It is currently pretty hard to test this theory out in the water. So Alastair and his team have set up scenarios that mimic this potential electromagnetic field effect in their lab. They did it using a water filled tank with a large coil of copper, called a Helmholtz coil, placed underneath it. And by putting crustaceans in the tank, Alastair and his team have made some striking observations...

Alastair - With edible crabs, brown crabs, when we have electromagnets under their tank and we switch them on, the crabs tend to triangulate on the magnets and then sit there without moving very much. It tends to reduce their activity levels quite substantially when the magnets are on. So it looks as though the magnetic field might actually reduce their natural movements, which might reduce their interactions with other members of the same species, so potentially mate finding, and it might also reduce their ability to forage, to feed and find food

Chris - In terms of developing offspring, the magnetic field also appears to impact another species too...

Alastair - We found that when female lobsters with eggs were exposed to the magnetic fields throughout the eggs developmental phase, the larvae were almost three times as likely to be disrupted in the development in terms of physical deformation and morphological changes. That had an impact on their ability to swim and swimming for these larval stages once they've hatched is very important because they need to be able to swim up to the surface to obtain food.

Chris - Now it's unclear if the cables currently sitting on the seabed have these impacts on crustaceans in the wild, but burying the cable was under the sand, as most companies do, might...

Alastair - Burying the cables would clearly be beneficial because the magnetic field round the cable drops off relatively rapidly with distance.

Chris - But continuing to study these effects, both in the lab and on the shore is important if we continue to move to more offshore wind energy in the future...

Alastair - It's important to know that we're not having unintended negative consequences in trying to do something good. Are the magnetic fields sufficient to disrupt the migrations of male crabs, which might have implications for the population biology of these species? How small a small effect is actually not significant as far as survival of these organisms is concerned, either as larvae or as adults? We don't really know that and we would need to do further tagging experiments to see what sort of movements might be affected by the cables in practice. We might also need to think about the impact of construction of these facilities, which clearly are on quite a large scale as well. The current practice would appear to be adequate, but we still have to continue research to make sure that there aren't any other unintended consequences.