Feral cats

Feral cats are a bit of a problem around here. We have about half a dozen that sit around the walls of our courtyard. If we leave the door of the cave open, they make themselves at home in there. If we are not careful, we will have a nest of kittens in there. I thought a bigger cat might be a deterrent to the others, but this one, belonging to my neighbour, seems extraordinarily slothful. It is very good with children apparently!