New South Wales
They only shoot when they have LOS. All other times they are moving towards the noisiest zone.
To be exact, they shoot when they have LoS to Survivors in range (0-3). If they don't have range, but can see Survivors, they'll head towards the loudest group they can see, going to the noisiest Zone if they can't see anyone at all.
I'm fairly certain you knew this already, but the way you worded it missed the case where Survivors could be seen only at long distances.