Sounds...

For an interesting experience, especially if you have a variety of animals, go into your herp room, in the dark, and just sit and listen.

I did just that today, as I was putting some feeder fish in with our alligator snapper.  As most of the animals could not see where I was, they were doing various things.  One large sulcata tortoise was grunting.  Almost sounded like burping.  Our Yacare caiman was roaring, or rumbling, as he was calling out to our female crocodile.  He does that when, we assume, she's in heat, although we don't know where or when.  She never exhibits any signs, and they cannot see each other.   Today he was out of his pool.  When  he does it in the pool, you can see the water bubbling. 

Occasionally you'll hear the rattlesnakes rattling.  They flexing their muscles or are they seeing shadows?  Perhaps just dreaming?  Like when your dog whimpers and runs in it's sleep?    All in all, very interesting!