How many birds are killed through windows

BMBF protects birds from invisible death

Ms. Förster, when people think of a bird strike, most people tend to think of birds caught in aircraft turbines. Why is deadly flying against glass panes so unknown?

It is true that the death of birds from aircraft turbines as well as from wind turbines has long been on everyone's lips. In contrast, the death of birds on glass panes was rather ignored. Even many people in the field were not aware of the extent of this problem for a long time. That's strange, because the first studies on this were already carried out in the USA at the end of the 1980s. Nevertheless, nobody in this country has dealt with it. We want to change that with our project.

What are you doing there exactly?

It's all about education. We want to open people's eyes and explain to them what the solutions to the problem can be.

How big is the problem? How many birds per year die this way?

At least 18 million - per year, and only in Germany! Studies from the USA have shown that an average of one to ten birds per year die in every house. There are around 18 million residential buildings in Germany - this is how we arrive at this number, and that is the smallest possible. This does not yet include the losses caused by the huge glass facades on office buildings. The number of unreported cases is likely to be extremely high. According to projections, there could be up to 100 million birds dead from glass accidents.

That's an incredible number! Why is so little heard of this problem?

Because the birds don't stay in piles in front of the glass facades. They are eaten by cats or birds of prey, or fly dazed into the nearest bushes. In addition, the caretakers at many large problem houses are asked to clear away the bird corpses first thing in the morning - unfortunately, that's no joke!

Why do birds fly against windows at all?

For the same reason that people run into glass doors: Because they can't see the glass! Birds can see like us. This means that the glass is transparent to them or it is reflective. If it is transparent and maybe you can still see trees or the sky behind it, you simply do not see the glass. If the panes are reflective, it still looks to the birds as if it were going on behind them. You fly against it without braking….

... and mostly die. What exactly?

It sounds harsh, but ideally, they'll be dead instantly from impact, such as a broken neck. However, many are still unconscious on the floor and only die later, for example from a cerebral haemorrhage. Birds' bones are hollow and break easily. Many glass victims recover from the first blow, but then can no longer fly and become easy prey for cats or they starve to death.

What should I do if I find a bird still alive after a glass accident?

If you can: get a cardboard box and poke holes in it for the air supply. Then put the bird inside so that it is in the dark. Very important: do not give water or food! Otherwise the dazed animals could choke on it. When the bird has struggled, you can simply release it again. If not, the bird should be taken to a so-called feeding station. You can easily find them on the Internet, for example on the Wildvogelhilfe website.

Are there other traps for the birds besides glass office buildings?

Yes, for example bus shelters like those at bus stops. Today they are almost always made of glass in order to avoid fearful spaces for the passengers. For the birds, however, these houses are usually always right in the way. Conservatories are also dangerous because they are in the middle of the green and are also made of glass.

As a homeowner, what can I do to prevent bird strikes on my windows?

First of all: don't fall for the fairy tale with the black sticker birds. Studies have long since shown that they do not help at all. The birds only recognize the stickers as a black spot and not, as it was actually intended, as a bird of prey from which they should flee. It often happens that the birds fly against the windows right next to the stickers.

But there are other options, for example foils with so-called highly effective patterns. These were recently even tested for their effectiveness in a flight tunnel. Small stripes or dots work best. You can stick it as a film on the panes.

Why does hardly anyone do that?

Put simply, because these measures - especially the adhesive films - are unfortunately a bit "unsexy". The patterns have to be applied over the entire pane and of course take up a small part of the view. Unfortunately, no completely transparent film has yet been invented that will keep the birds away anyway. If you want a more pleasant look, you can also use cord curtains, fly screens or special window colors. You can use it to simply paint on the panes. Bird protection and art are a good combination!

The BMBF voluntarily protected large parts of its glass surfaces with an effective pattern. Shouldn't such measures even be required by law?

It would be very easy to change something and there are even laws for it. Up until a few years ago hardly anyone knew about this, so they simply weren't adhered to. Many authorities are now demanding protective measures when they issue a building permit. These are normal requirements, as they have long been known from other areas of nature conservation. It is our job to ensure that these requirements are met even more closely in the future.

Ms. Förster, thank you for talking to us.