If this information has been released before, I have never seen it, as I have asked about it and gotten no answer. So I did some messing around and here is what I found out. If anyone is interested, it is all music based research.
I welcome comments and such, and please feel free to experiment with it, and if it has been done before, it happens. Hopefully someone can use this in one of their mods, or even better, expand upon it. Have fun!
I forgot exactly what the nature sound effects look like but its just like the music header in a scene. (I forgot where all the scene listings are)
Look at the Night time scene offset of a map and there will be no music header, instead shortly after I believe there will be one byte (or two?) and that would control your nature sound effects. You can listen to all the nature soundfx in the Audio Debugger (81210B2C 0101).
Sorry I can't provide much help. I currently don't have a debug rom or emulator. But if there are some scene listings around, I'd be glad to help.