It's all related isn't it? For instance, the wedgies got to "unnatural" numbers in some regions because of land clearing plus introducing lambs and bunnies; and also there can be a reduction in foxes when bunnies are reduced, albeit also there is an initial shift to more native prey...impossible now to reverse the damage we have done to our natural ecosystems...although there are benefits in continuing adaptive management initiatives if there is a net benefit to natives...eradication typically only works on islands or isolated areas.
It certainly is all related - Gerald Durrell's "spider web". And, certainly impossible to eradicate. However, nature will [almost] inevitably win in the end. Nature will just evolve to incorporate the newcomers - one way or another.
There is a feral pest "industry" in this country at the moment and millions of dollars are being misspent on wild goose chases.
Cane Toads are a classic case. They will never be eradicated. Yet scientists, and others, are begging for more and more grant money to find ways to eradicate them. Can't be done - any more than rabbits, foxes, cats, Indian Mynahs etc, etc will ever be eradicated. Minimising numbers is all that we can ever achieve.
Interesting thing about Cane Toads is that nature will eventually work out how to live with them. Years ago, when I lived in central western Queensland, the Cane Toad invasion rolled through my area. Within months we lost every species that ate amphibians. No more Monitors, Black headed Pythons, Collett's snakes etc. Autopsies on the bodies showed them to be full of toads. Within 15 years they had all returned, repopulated from the fringes of the devastated areas, and now living in harmony with the toads. Some species learned how to avoid the toad's toxin glands [Crows, Kookaburras, Magpies etc] but the others just leave them alone.
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) than on the real issues Further, we have those damn introduced cane toads to content with ... (talking of another introduced big threat to native fauna).