In the past I unloaded to exhaustion on a couple of the poop threads (pardon the pun) which are similar to this one. I've come to the conclusion that the modern American panacea, education, is not the answer. Nor is more information (signs). The answer is punishment, pure and simple. The only sign that would work would be one that said "$20K fine and / or 10 years hard labor - Rangers are authorized to shoot on sight". Everyone would be pooping in wag bags and jumping for joy to do it (though not at the same time, most likely), and packing out everything.
