Not specific at all, but the sudden change in demeanor and the apparent inability of most people to read feline body language would likely result in a lot of them getting killed if it were not for the fence. That or turning their back, which the tiger is [i]exceedingly[/i] partial to becoming aggressive toward. He becomes, from one moment, tolerant and perhaps even social, to crouching and quickly stalking - getting as close as he can manage to his fence line and nearly pressing his muzzle to the metal or ports.