Germany promotes window markings to reduce bird deaths from glass collisions

Millions of birds die each year in Germany after colliding with glass windows, a hazard caused by the birds' inability to recognise transparent surfaces and reflections. The Naturschutzbund (NABU) estimates up to 100 million fatalities nationwide, with Berlin alone accounting for several million deaths annually. Conservation groups such as the Wiener Umweltanwaltschaft (WUA) recommend applying patterned stickers or points to the exterior of windows – 1.2–2 cm in diameter, spaced no more than 9 cm apart, in high‑contrast colours like black, white, orange or red – to make the glass visible as a barrier.

The measures are simple and inexpensive compared with larger architectural solutions, and they can be combined with interior curtains, external screens or blinds to further reduce reflections. High‑profile incidents, such as the 2024 mass collision at Chicago’s McCormick Convention Center that killed nearly a thousand birds, underscore the global scale of the problem and the need for widespread adoption of mitigation techniques.