Confinement, trapping and killing and trapping and removal of cats fail to control numbers because these actions create habitat vacuums. Nature abhors a vacuum. Individuals of the same species from areas surrounding a newly created vacuum move in to recolonise it. This is a scientifically recognised occurrence among animal populations.
There is no such thing as a cat-free zone in an open system that can sustain cats, unless there is something that keeps the cats out 24/7.
Scientific evidence has proved that confinement, removal and killing of cats actually increase the numbers of cats, destabilises the ecosystem and creates a danger to native wildlife. So, the incorrect propaganda that has been spread that confining pet cats will save native wildlife is wrong.
The best thing for native wildlife is to have desexed, well fed cats that hold their territories and stop new cats from infiltrating and breeding.
By this method, the numbers of cats reduce to the minimum that can hold the territory against new undesexed cats, while controlling the rats and mice and also deterring the snakes which are attracted by the rodents.
Cats are the safest and most efficient rodent controllers and are far better for the native wildlife and the environment than baiting, which poisons the native wildlife, other animals like cats and dogs and pollutes the land and the waterways.
Cats are also a kinder way to control rodents than baits, as poisoning causes terrible suffering and an agonising death, with animals taking up to 8 days to die.