I'm not an expert, but people in Australia who are experts think that feral cats are a huge problem for native wildlife. I know in some areas you can get a bounty for bringing in dead cats. There's also programs that do sterilization and poisoned traps

Interesting article here, which I think I originally saw on HN: https://www.nytimes.com/2019/04/25/magazine/australia-cat-ki... Some of the pictures are a bit unpleasant, but part of the article is about the visceral backlash to killing cats even when it is almost universally agreed to be for the greater good