This notion of pristine, permanent environmental stasis has no basis in reality. All their so-called “native” species very likely arrived from elsewhere at some point. They’ll adapt as the so-called “invasive” species will. They’re not saving anything other than a storybook tale they’re telling themselves due to leftists attempting to hobble them economically.
You need to look up the rabbit proof fence they had in Australia
“The State Barrier Fence of Western Australia,[1] formerly known as the Rabbit Proof Fence, the State Vermin Fence, and the Emu Fence, is a pest-exclusion fence constructed between 1901 and 1907 to keep rabbits and other agricultural pests, from the east, out of Western Australian pastoral areas.”