I can't find any videos of the actual scene, but it this has been something that has bugged me for YEARS.
Do you recall at the start of Godzilla rampage at the power plant in the Return of Godzilla, there is a scene of a marsh, and some birds fly away. During this scene, there is a bird call that happens, and it has been haunting me for years. Every once in awhile I think I hear it in a video. I definitely heard it during the brief period of time I lived in Japan.
Does ANYONE know what type of bird that makes that sound? This is the closest approximation I can think of, and it may actually be the source of the sound: