some birds have especially good eyesight, particularly birds of prey which can see their tiny prey, mice and such moving down below when they lock on their target and swoop in for the kill. ever heard the phrase, eagle-eyed? It would make sense that smaller birds like sparrows and warblers also have good eyesight, if not as good as raptors. Though there is concern with windows and birds, as they are not able to distinguish that there is an invisible barrier made of glass, and they fly into them. This is a real problem as many birds die from flying in to windows.