What a Bird Sees When It Looks at Glass
A bird navigating a city skyline does not perceive glass as a solid surface. Its visual system, built for detecting movement, colour contrast, and open flight paths, reads a reflective facade as a continuation of the environment behind the viewer. A window reflecting a tree canopy or a patch of open sky registers as exactly that, a tree canopy, an open sky. The bird does not slow down. There is no learned cultural knowledge of glass as a human invention; there is only what the eye reports, and the eye is wrong.
