In regards to the salvators you've worked with, I remember you saying you had done research in their intelligence and wasn't sure if you could shed some light on something for me. Our male (Darwin, about 5.5 ft long including tail) has done something with us since day 1 (we've had him for about 3 years now), which I can only relate to as a "sighing" noise. It's definitely not hissing (he's very mellow and tame and seems to like attention) and our thoughts on it was, it was his way of trying to communicate with us. The reason we think this, is the length and loudness of the "sigh", varies depending on his mood so to speak. He does a very loud short one, if we're moving him from some place he wants to go or shouldn't be going, and a softer longer sigh if we're in his room talking to him or giving him a bath (things he seems to enjoy).

I didn't know if you've noticed this with other salvators you've worked with, or any other large monitor for that matter.