Oh dear, I am a cat lover and I get upset to read about people wanting to harm them (or harm any animal for any reason come to that) because they poo in their gardens. Why does the cat deserve to be shot because it is pooing! We all have to poo after all. Someone shot my previous cat with a pellet gun - I will never forget her bewilderment and distress when she came home.
I know it's nasty but heck, where can they go? Cats are not dogs - you can't take them for long walks on a lead, I personally think it's cruel to keep a cat indoors unless there is a very good reason. When I see my little tail-less, broken hipped rescue cat sunning herself and rolling happily on the lawn, I have a lovely warm feeling about the fact that she is alive and enjoying a life that she could so easily have been denied (I mean she would have been euthanased)
You simply can't follow a cat around. I do keep my cat in at night and she does have a litter tray at all times, however she rarely uses it.
I think the idea of an outdoor cat litter area is a good one, but again, you can't make the cat use it. My mother in law used to save rose prunings and place them around the garden - the thorns put the cats off digging there.
ariadne xx