Birds being shredded by wind-turbine blades has long been a visual used to support arguments against wind power.
A great deal of work has been done — and continues — on how to prevent bats and birds from colliding with turbines, while developers pay strict attention to wildlife habitats when selecting sites.
But it seems some birds are more open-minded when it comes to wind farms. Breeding boxes fixed to turbines in the western German state of North Rhine Westfalia (NRW), as well as in neighbouring Hesse, have been home to successfully breeding kestrels, and more recently peregrine falcons, for more than ten years.
Yet, NRW nature protection authorities are calling for the breeding boxes to be dismantled. Local Green Party member of parliament Wibke Brems has asked for government clarification.
Brems suspects the NRW nature and environment authority is keen to rule out any precedent that could show wind turbines are compatible with rare birds and, therefore, wants breeding boxes removed. She describes the situation as "simply absurd".
There is concern that the state’s conservative/neoliberal government, which replaced the Social Democrat Party-Greens coalition in 2017, is raising the hurdles for wind-farm permitting.
The NRW government has acknowledged that freely accessible breeding and resting places for protected species in the natural habitat have to be safeguarded, regardless of whether they are natural or artificial, as long as they are used regularly for breeding every year.
But it also noted that 2013 species protection guidelines for NRW only accept breeding boxes as a temporary measure, saying that such bird-protection measures should not be carried out where "sources of disturbance" are present.
The issue becomes more pressing where repowering is planned. In principle, no repowering permit can be granted if a protected species that could be endangered by impact with wind turbines has made the existing project its home, according to Dirk Sudhaus, managing director of German onshore wind agency Fachagentur Windenergie an Land.
Environmental and nature mapping and monitoring of proposed sites was in its infancy in the early days of onshore wind power, therefore "the protected species may have inhabited the wind-farm area from the start" he says.
This changed after new nature protection laws were introduced in 2009, based on EU requirements. Species protection now includes strict prohibition of killing, disturbance and habitat destruction.
The current approach is to consider ways to attract endangered species away from wind farms, and build such remedial measures into permit conditions, Sudhaus explains. However, such measures have to be proven to be effective, and that takes time, he adds.
A case in point is protecting space for bird migration. To ensure migratory routes are kept free, old wind turbines may not be replaced at the same site because new machines are bigger and taller. Wind turbines may be refused permits along rivers, streams and waterways as these are often part of migration routes.
But there are remedial measures for migratory routes, Sudhaus insists. Cranes generally cope well with wind turbines, but not in weather conditions where visibility is bad.
So, with knowledge of how fast cranes fly, bird stations in northern German can notify wind farms further south of the cranes’ approach so turbines can be shut down as they pass by.
Since this is only necessary in foggy weather — when winds are usually low — turbine operators lose little earnings.
For bat movements, the potential danger periods are in autumn at dusk, with no rain, temperatures above 10oC, and wind speeds below 5m/s, so wind turbines can be stopped when these parameters apply, Sudhaus says.
Similarly, agricultural cultivation can be adapted to enable a wind project to be permitted, depending on which species are found during the initial wildlife monitoring of a potential site.
The Montagu’s harrier tends to breed in winter cereals, so one solution is to plant summer cereal near wind-project sites to encourage the birds to go elsewhere.
In contrast, the red kite can be drawn away by planting winter cereals around the wind farm because the high and dense growth means the birds cannot find prey.
Other aspects of cultivation also play a role. When crops such as grass or lucerne are mown, small animals are often killed during the work and the birds are attracted to the site to collect the carrion.
The first mowing is the most problematic because the high grass has protected the animals and the birds are hungry. A solution may be for farmers to notify wind farms that mowing is imminent, so wind turbines can be switched off for two days after mowing, Sudhaus suggests.
Such measures require close coordination with farmers, who could be compensated for changing their crops and how they rotate them. Getting a wind farm permitted could require signing 20-year contracts with the farmers cultivating the land.
The legal aspects can be demanding because the farmers do not always own the land, the land may change hands over the period, and the turbines can be spread over several owners’ land, Sudhaus says.
The most important measure to avoid conflicts with nature and protect wildlife is the choice of site, he stresses. However, site pressure and the dynamics of nature make further measures necessary to avoid killings, in particular attracting endangered species away from potential and existing wind-farm sites.
At the same time, such precautionary measures are only necessary when an increased mortality risk is predicted for a protected species. German courts refer here to a significantly higher mortality risk and mean risk that is over-and-above the normal mortality risk, Sudhaus points out.