Predator Free Zones?

Nw Zealander Elizabeth Bell's Wildlife Management International has been employed to eradicate introduced predators/pests on around 30 islands around the globe. There's no doubt that introduced rats, mice, feral cats and rabbits (also possums and some primate species- perhaps unmentioned for sensitivity reasons?) can decimate ground nesting or flightless birds. Endemic populations on small islands, are often particularly at risk (https://www.theguardian.com/environment/2023/sep/10/she-kills-to-be-kind-the-mastermind-ecologist-eliminating-invasive-predators-aoe). How does this fit with the general idea of ecological balance, where predators and prey coexist? There have been cases, where the complete elimination of predators resulted in environmental damage, eventually endangering the orininally protected prey species. A number of conservationists are also advocating the introduction of predators, like the Eurasian lynx and the Grey wolf, to specified locations to control herbivores. It seems likely that Bell's techniques are largely applicable to particular sets of circumstances. In her native New Zealand, in the absence of mammals, birds once filled all the environmental niches. The arrival of mammals (especially rapidly-breeding ones such as mice and rats) endangered many unique bird species (as did human mammals, with the Moa). In effect, the arrival of the mammals destroyed an already existing ecological balance. In other locations, ground nesting birds, congregate on islands precisely to avoid land predators. The arrival of introduced rats and mice is often catastrophic to these colonies. These birds are not, however, actually'predator free', as eggs and chicks can be taken by other birds. The breeders are also, of course, also subject to predators, when going about their other activities. What Wildlife Management International does is clearly very valuable and applicable to small specific areas. As a former PhD student of mine, who worked on endangered Mauritian birds, once said "We conservationists can be just glorified rat catchers!"