The result at the beginning of the investigations in 2006: at that time, thousands of birds even died on the brightly lit façades of the Post Tower. At that time, the façade shone in bright colours every evening due to the fluorescent tubes in every window.
The post office has subsequently made improvements again and again, but according to Haupt, it is still not enough. "Emergency lighting still leads to hundreds of casualties in the autumn." According to the Ländergemeinschaft der staatlichen Vogelschutzwarten, this is ten times what can be considered unavoidable.

The bright light causes problems for the birds

Why the light causes so many problems for the animals has not yet been fully explained scientifically, Haupt says. Ornithologist Darius Stiels from the Koenig Museum told GA about two years ago that the light attracts birds. The animals are literally caught by the stiff light and are confused by it, he explained at the time. "Then they fly against man-made structures like buildings and masts." Haupt agrees. "The light sources cause birds to become disoriented." How exactly birds orient themselves is a complex process, he says. In general, the animals use the earth's magnetic field. But their orientation system only works in the dark, Haupt adds. Artificial light means the animals no longer perceive anything. "Humans, for example, are also blinded by car headlights. With birds, the disorientation just lasts longer."

Other problems at the Post Tower

In addition to the completely illuminated façades, Haupt therefore also repeatedly criticised the illuminated logo in the past. "That shone vertically upwards." Even if birds only fly through this cone of light for a short time, that is already enough to confuse the animals, he said. "It makes it difficult for them to find their direction of migration and they fly in a different direction." According to Haupt, the logo has been switched off in the meantime. The Bonn biologist hopes it will stay that way.

The cobwebs on the facades are also a problem for smaller birds when they fly against the Post Tower. They get caught and then slide to the ground. There, the cobwebs act "like shackles" for the animals. "On the ground, they don't stand a chance, as cats and maggots see them as prey."

In order to identify and minimise all these sources of danger, Post spokesman Alexander Edenhofer says the Post began discussions with the study's authors after the initial observation phase. "In the course of this process, a six-figure sum has been invested to implement a variety of measures in the interests of bird protection, such as installing twilight sensors throughout the building." The lights in the offices would turn off every hour in the evening to avoid employees forgetting to turn off the lights themselves. The company has also reprogrammed the window slats, he said. In addition, the Post has installed an interior privacy screen, the lighting of the logo on the roof is currently switched off and the cleaning intervals have been adjusted. The Post has also installed a special foil and a special bird light. Since 2008, the more than 160-metre-high Post Tower has shone in a discreet blue, with black surfaces that look like birds moving on top. This combination is supposed to be highly visible to the animals.

Biologist Haupt: Post's improvements do not yet provide sufficient protection

According to biologist Haupt, this is "okay" as a measure in contrast to the often-used bird-of-prey stickers. Because these usually do not work at all to protect the birds from collision, Haupt explains. But "there is still light coming through the window panes. The emergency lighting needs to be better shielded." In addition, he says, the large glass areas on the building's tower remain unsecured and the post office still fully illuminates the façade on certain occasions. "In the middle of train time, it happens again and again that they turn on the lights completely," Haupt says.

However, the Post does not see any further need to catch up at the moment: "The measures have been implemented for many years. If there are new findings that make it possible to make a further contribution to bird protection on buildings, these will be tested for their effect and feasibility," concludes Edenhofer.

According to Haupt, however, the Post Office can only do damage limitation in terms of bird protection. This was simply forgotten in the planning of the building. That is why Haupt will continue to fight for bird protection at the Post Tower, but also at other buildings in Bonn.

(Original text: Wiebke Elges; Translation: Mareike Graepel)