They don't all do it so some must need eyeglasses.
They can see through it so they think they can fly through it. Many birds suffer very bad head trauma from this and some die. Some are just stunned and if kept in a box in dim lit room for a few hours will recover fully. I put decals on my windows so this does not happen. They sell nice frosted ones.
rehabber
It is probably a double pane window. If I stand on the porch and look at ours, I see the hillside across the road. So do birds, they think they are flying into the woods, they can't see the glass, in double pane windows, because it is reflective. If you can pick them up quickly, most times they have just knocked themselves out, and will come to and fly away. If left to lay on the ground, they usually die. Have a heart, pick the bird up, like I do, stroke it, until it comes around, then sit it in a bush or shrub.
its because they dont know theres something there. i mean, who told a bird theres a such thing as windows lol. maybe the bird just saw some food, or something that he wanted and he got curious, lol. i bought a bird at the pet store that had a "disability" because the same thing happend. ( i felt so bad for it!!! )
i know about over a dozen birds have run into my glass windows, including a falcon chasing a swallow. It is because they are either so focused and going so fast in flying they cant see it or they dont have time to avoid it
experience
There eyes aren't as sophisticated as a humans. They think of it as we think of an open door. They don't realize that it is solid, and that they can't fly through it. Its invisible to them. Sorry that you had to witness that birds death...=*(
The window is so clear that birds can not see it. Which is why birds fly into windows. That happened to my mom except she was in a car and it hit the window. I think it died.
They can't see the glass. Pet birds think its a way out and wild birds either see that it doesn't look like what they're used to and stay away or don't see the window.
the window was probably clean so the bird didn't see it and thought there was nothing there, so it flew on and then ran into the glass.
myself
because they think its nothing and end up flying in to it
my friend had a big window and it was flying full speed like nothing and crashed
the windows are clear and they can't tell something is there ..o and some birds probably die whilst flying so i guess every now and then they hit a window
They do not see the window and wanna come inside. Are you saying you have never run into a sliding glass door before?!
I ran into my glass door, twice.
maybe the windo was so clean they didnt notice it ahead of them... too much windex???
They don't see or understand them.
An old bird brain.
the term birdbrain comes from that from the late 1900s
to them they thinks it a way out to freedom
Because they can't see it.