In concrete terms, woolly mammoths don't seem likely to starve endangered Siberian animals, and if they turned out to be an ecological problem (for example, the

In concrete terms, woolly mammoths don't seem likely to starve endangered Siberian animals, and if they turned out to be an ecological problem (for example, they might eat important plants to an excessive degree) they would be fairly easy to capture, move and confine. In abstract terms, there is only a small difference of degree between capturing, reproducing and dispersing rare animals to increase a small population (for example, small raptors in cities as a defense against obnoxious birds); reestablishing a recently extinct population with imports from a place where an animal isn't extinct yet (for example wolves and bears in various places in central Europe); reestablishing a less recently extinct population with artificial marvels of genetic engineering (mammoths, aurochs); introducing completely foreign animals (for example rabbits in Australia, a major bad idea from a conservation point of view); introducing artificial animals that never had a population anywhere (hopefully all fiction, but for example photosynthesis would be impactful).