Windows: The Invisible Killer

There is a myth that people can see glass, but birds can’t. In fact, neither birds nor people can see glass.

Many people are injured every year by colliding with unmarked doors and windows; embarrassment is the usual result. But because of their small size and high-speed flight, birds hit glass and are usually killed or sustain injuries that will likely kill them.

Birds can learn to avoid glass: for example, birds in zoo exhibits learn to avoid exhibit walls if the glass is marked for the first few days of their residence. Wild birds can learn about specific pieces of glass.

But overall, birds don’t seem to be able generalize clues that windows are present, and frequently don’t survive the first impact.