Unnatural Disaster: Why Birds Crash into Glass

You’ve seen or heard about this. We even have safety protocols in place to protect the flying creatures. But something just doesn’t add up: How can the animals with the best vision in the animal kingdom not sense when they are about to fly into a window?

If they use their UV sense to navigate, it’s possible that the UV light would shine through the window, instead of being reflected by it. This would keep the birds from flying into the side of the house, but would make them more prone to fly into windows. 

We know that they don’t just fly into the side of solid structures. So it’s not a navigation issue. What types of glass ward off bird crashes? In looking at the recommended solutions to this issue, one thing is clear [no pun intended]: the glass has lost its uniform transparency. The manufacturers are essentially just breaking up the glass into smaller sections. The section breaks are visible. They have an entire lab dedicated to testing these window setups, so we know they work. We just don’t know why.

Solid objects absorb photons. Clear objects allow them to pass through. Thus, the clear objects don’t behave like solid objects in respect to this sense. They behave almost exactly like empty space. 

If birds use a sense that we haven’t discovered yet to navigate, it would make flight much easier. If they can see this portion of their sight, they can essentially avoid flying into things with unbelievable precision. But when we introduce transparent objects into the natural world that don’t react with light like ordinary objects, the creatures with the best eyesight on the planet can fall victim to a pane of glass.


  1. https://abcbirds.org/get-involved/bird-smart-glass/
  2. https://www.allaboutbirds.org/why-birds-hit-windows-and-how-you-can-help-prevent-it/
  3. https://www.cachevalleydaily.com/news/archive/2019/06/20/usu-professor-says-window-collisions-kill-nearly-a-billion-birds-a-year/#.XSIiuS2ZPSw
  4. https://earthsky.org/earth/why-do-birds-collide-with-windows


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