Wind Energy And The Eurasian Eagle Owl

Climate change threatens many animals’ existence and well-being, and wind power can help reduce greenhouse gas emissions that are responsible for these effects. No energy source is perfect, though. While wind energy is often praised as a more climate-friendly energy option, wind farms and power lines may harm local bird populations by causing changes in their habitats and directly killing birds who fly into the turbines. Furthermore, the noise disturbance of building wind farms may impact sound-reliant animals, including owls who often rely on noises to hunt.

With these tradeoffs in mind, the authors of this study measured changes in Eurasian eagle owl populations of central Norway by looking at 39 eagle owl territories both before and after the construction of nearby wind farms. They found that eagle owls were more likely to abandon their territory if construction took place near a construction site (specifically, within 4 to 5 kilometers), and that owls living further from the construction tended to stay put.

The authors provide three main reasons why eagle owls may be vulnerable to disturbances from wind farm construction:

• Eagle owls may be killed by direct collisions with wind turbines. They are capable of flying upwind and often fly high enough above the ground to run into turbine blades. Eagle owl deaths due to collisions with wind turbines have been observed elsewhere in Europe.
• The owls may tend to leave nesting sites where they feel disturbed by noise from construction. Eagle owls’ wings are specifically adapted for flying quietly, seemingly to make it easier to listen to their prey’s movements while hunting. Noise has been shown to make hunting more difficult for a variety of other owl species across the globe. However, the authors say that little research has been done on whether eagle owls are significantly affected by human activity.
• Other animals that the owls rely on for food might die or move away from the construction zone, causing the owls to move elsewhere in search of food. The authors did not collect data on the abundance of the eagle owls’ prey, though, so this hypothesis couldn’t be confirmed. 

Contrary to the authors’ expectations, they did not measure any decrease in eagle owl breeding after the construction. In fact, there was more breeding closer to the construction area than further away from it both before and after building began. They point out that the owls prefer to hunt for their prey in open areas that are also better for wind farm construction. Also, when some eagle owls leave an area, more resources become available to those who remain, which could allow them to successfully raise more young. As a result, it may be difficult to measure the negative effects of wind farm construction by only looking at breeding.

The study only captures short-term changes to eagle owl activity right after the construction efforts were completed, and eagle owls are known to be very reluctant to leave their historical nesting locations. This means it’s possible that there will be more severe long-term population declines that the authors did not measure. It is also possible that the owls will adapt and that their populations will recover. The authors note that under the right conditions, eagle owls can coexist with human activity and have even been known to live and reproduce in major cities.

In short, eagle owl populations can have at least short-term declines when human activity is introduced into areas that have had few human disturbances in the past. When the wind farms involved in this study were being built, turbine locations were chosen so as to avoid being less than 1 km away from any known eagle owl nests. The authors urge that future construction activities continue to take the interests of eagle owls into account so that the owls can continue to thrive in the wild. They recommend that people study the eagle owl populations of any area before construction begins. As we look for solutions to climate change, animal advocates must continue reminding policymakers and the public of the potential side effects for animals.