it means that a small yellow bird is on your window screen
Not in today's world.
It could mean that the bird sees its reflection in the window and thinks that it is seeing another bird, or it could mean that, at some time, someone put out bird seed onto your window sill.
It means that was a tough and lucky bird. Other than that it means nothing whatsoever.
If a bird flies into your house, open a window or door to allow it to fly out. Avoid chasing or startling the bird, as it may become stressed. If the bird is injured, contact a local wildlife rehabilitation center for assistance.
Yes, it is bad for a bird to hit your window. If it is going at a fast enough rate of speed, it could break its neck, which would kill it. Alternatively, if you are living in a skyscraper and the bird hits your window, it could knock it out and then it would fall to its death. But many times it just shakes its head and flies off. It would depend upon the bird and the window. But no, it's not a good thing when a bird and window intersect.
Is it bad luck for a bird to fly into a window and die
It is almost certainly a male bird fighting his reflection, thinking it is a rival.
If it is a blue bird which seldom flies and lives in a wet area, it is probably a coot or a swamp chicken.
Yellow warbler is a bird that flies. It begins with the letter Y.
It might have just been a stupid bird or it might have short sight or it might have seen its reflection and thought it was another bird it all depends on what type of bird it was.
Time to get a screen or close the front door.