Paula, I already own and use rat traps And I don't own a cat at the moment. But the neighbourhood cats at my old place did a pretty good job of keeping the rat population in our street under control. That was in a semi-rural suburb. I'm happy for the cats in that situation to be out at night. Most of the native wildlife that cats kill is birds and they do that during the day. I did have lizards at my old place, despite the number of cats. I know of other areas where people reckon that the lizard numbers increased when there were no pet cats, but they use rat poison to control the rats. Permaculture is site specific. What works in one neighbourhood isn't necessarily going to work elsewhere. And the situation in NZ is different than the situation in Australia or the US or wherever.