It is no exaggeration to state that the ecology of a place can be irreparably harmed by the introduction of exotics. In Grand Canyon National Park, we find numerous exotics, from approximately 155 non-native plant species (out of the Park’s more than 1500 total plant species) to exotic animals such as burros, trout, and mudsnails. We also find unnaturally large populations of native organisms (such as ravens, cowbirds, and in some locations, deer) sometimes due to the presence of non-native species. In the park service, there are guidelines and policies for dealing with exotics. These ultimately relate to the mission of the National Park Service, “... to conserve the scenery and the natural and cultural objects therein....”