Of course they kill rats. The reason why cats aren't having an impact on rat populations is fairly obvious: the rat is a versatile, fast breeding species that is capable of living in a variety of habitats. It's pretty much an invulnerable species. How, without creating a lab-grown virus, would you go about killing every rat in the country? It's pretty much impossible.
The logic of 'cats kill rats and rats aren't going extinct, therefore cats can't be making other species extinct' is dim. There are many other more vulnerable, less flexible species out there. An unfortunate number of these species are easy prey for this country's 10 million cats. Are cats the sole cause? Nope. Are they a significant contributory factor? Yup.
TBH I thought people on this forum were supposed to be relatively smart. It's amazing how blind to reality people can get when there's a cute little ball of fur pulling at their heart strings.
For the record, I do like cats. They're adorable. I'd never own one though for knowledge of the impact they have. I can't justify it knowing and understanding the impact they have on the wider world. There's a campaign being run in New Zealand at the moment, encouraging people not to replace their cats when they die - they're driving the Kiwi, the national symbol of New Zealand, to extinction. It's shocking to think that such an iconic animal could be relegated to zoos by the time I have grandkids, all because of a situation totally within the control of Western Civilization. Many of us were appalled by the killing of Cecil the Lion, we are prepared to criticise people in far away places who hunt Rinos, Elephants, Tigers and Lions to make a living, yet most of us won't make one simple change that could affect the future of dozens of species back home.