If it's in a grassy jungle area you could have it munging on some grass Give it's head a little wist and throw back to make it look like it's swallowing as the player gets close. Allowing it to get ready to attack. Else wise maybe just a head bob or tail wag or something. If it's lying down Maybe a little black bubble blowing up and then dwindling. Popping for character approach. Just a couple suggestions.