Birds tend to fly into wind turbines by mistake. There are a few reasons for this.
One major reason why birds cannot easily spot wind turbines is that the long, rotating blades create a misleading view of empty space as they spin rapidly.
Birds often collide with turbines for years without being able to avoid doing so.
In recent years, however, researchers noticed that some types of wind turbines seemed to alter the flight path of birds approaching them.
They would slow down or turn back before reaching the area where the turbine blades rotated.
At first, it was unclear why these particular turbines were any different than all the others.
A hidden problem in how birds see turbine blades
There’s more behind it. The first reason is that the rotating blades of wind turbines appear unlike anything else birds normally try to avoid.
Not only do the blades move fast, but also the way that light reflects off of them means that there will sometimes be periods when the blades seem almost invisible.
This creates a serious risk of collision.
A second reason turbines pose hazards to birds is that they are much more likely to approach standard white blades than other designs.
Scientists believed that they needed to make the blades more visible. Previous studies had shown that birds would continue to fly towards the new colored blades as though they saw no difference.
It seemed as though changing the color of the blades was not enough.
Subtle changes in bird flight behavior
The next stage in research was to find out if there were other ways than just determining whether or not animals could see the turbines, to measure animal responses to different visual cues.
Birds in controlled laboratory environments were provided with a variety of designs for spinning turbine blades and compared against one another.
But when the patterns changed, their behavior changed — they slowed down.
They stopped and assessed the situation.
Sometimes they completely reversed course and went in another direction.
The greatest reactions occurred when using unusual patterns that had high contrast such as black, red, and yellow.
Researchers then focused on understanding why certain patterns created such a strong response.
Bird deaths from turbines can reach into the hundreds of thousands each year, leading researchers to study this behavior in “Biologically inspired warning patterns deter a passerine, Parus major, from digital turbine blades” published in Behavioral Ecology.
The thinking behind “snake” wind turbine designs
When researchers placed similar warning-style patterns onto turbine blades, they found that birds reacted differently. The change was noticeable almost immediately in controlled observations.
Rather than continuing to travel in a straight line, these animals will either come to an immediate halt or will turn abruptly off course.
This method is easy and direct. It doesn’t require creating new turbines, nor does it depend on birds learning over time how to avoid them in different environments or conditions.
The basis of this approach appears to rely upon signals that many species of birds may already naturally understand.
How patterned blades influence bird movement
Studies demonstrate that birds visit patterned blades significantly fewer times.
When they do, they hesitate more frequently, which can make a crucial difference in helping them.
That hesitation provides additional time for birds to alter course and remain distant from turbines.
Across large wind farms, even small changes could make a real difference, helping to reduce bird fatalities over time in many different regions.
If a single pattern can cause a bird to alter its course in mid-air, what other risks exist simply because animals perceive the world differently from us?