Why shine a flashlight on a bird in the dark and it won't move?

Because it will be temporarily blind and can't see the surrounding situation clearly, it will definitely not make a move. In fact, all nocturnal animals are temporarily blind under strong light, and they can't see clearly until their vision is adapted. Hunters use this feature to illuminate animals at night and then shoot.

When we suddenly enter a very bright place in the dark (or turn on the light in the middle of the night), we will feel that our eyes can't be opened.