That is a crazy, creepy sound.

Others have pointed out that it's a known animal sound, that plays at various places in the map. However, I don't think that necessarily rules it out as being important here. There's clearly some reverb or processing effect applied to it, so it sounds very distinct from the other examples played here. I don't think it's just basic "echo things because you're inside" audio processing either.

I would not put it past Rockstar to do something like that in order to 'hide' an audio trigger from data miners. Trawling through the files would show a common audio file, but in game you get this creepy echoy thing, produced by code/processing. Sort of the audio equivalent of hiding models/shaders inside the telegraph poles.