Yeah, in Australia the damage is more obvious. Here they aren't native either, but the native fauna did evolve with similar predators I guess, so their impact is more contested. It's really risky for the cats though, with all the cars and also things like rat poison. I mean, among my siblings' cats several died before their time, some less than two years old (my sister once even saw one of her cats get run over on the pavement right in front of her building) or just never came back and are presumably dead (cats have to be chipped here so it's unlikely they got picked up) and one even was shot (!!) with buckshot once (she survived and lived to over 16 eventually but it was discovered by a vet on an x-ray that showed metal pieces). My siblings still both think it's better they risk getting killed but can enjoy the outdoors. Personally I think they ought to look into spacious catios or such and make the indoors mire interesting with cat shelves etc. But even in shelter cat profiles you often see the stipulation that they will only give you that cat if it can go outside.