Bird (Mario's Time Machine)
From the Super Mario Wiki, the Mario encyclopedia
A Bird is a minor enemy in the NES version of Mario's Time Machine. They are brown birds that face the screen as they fly. If Mario tries to place an artifact in the wrong time period, or location within the time period, one will swoop down and carry said artifact away. On the Moon, they are replaced with a UFO with a yellow bird-like creature inside. In either case, the artifact will end up being returned to Bowser's Museum, and need to be collected again.