One of my best friends is the child of a bird-watching family. His folks are great supporters of preserving bird habitat and take true delight in the avian world. My friend is himself a bird-watcher and in high school I would go over to his house where he kept a BB gun. This BB gun was for shooting birds dead. Incongruous, no? When I asked him about this he informed me that the gun was for the shooting of starlings and other invasive species (to this day he hates starlings). In essence he was killing the foreign to preserve the native and by no means do I think he was wrong to do so. It is scientific fact that starlings were introduced by humans to the Americas and that they do indeed out-compete native species. My friend the bird-killer is indeed saving birds. The point in regaling you with this anecdote is to show the idea that drove Hitler and Stalin, Mao and Robespierre . culling the inauthentic and foreign to promote the authentic and native.