I spent all of 1978 in Australia. Weekends were at a family farm. Shot 75 - 100 Rabbits every time we were there with 22lr. We didn’t even bother to pick them up. Thing is it didn’t even seem to ever put a dent in the population and the people there the other 5 days a week also were killing them. Cats like Rabbits are a non-native species in a ecosphere without enough large predators to balance things out. I can definitely can see a need to control the population. Problem is, unlike the 70’s I doubt there are as many people out shooting in the bush these days.
Need to release a worthy opponent to the feral cat, say, a T-Rex. That will clean up the mess.