Of all of the natural resource management efforts in the parks, the most controversial was the killing of predators in order to protect more popular species. Predator control efforts in the parks were in accord with the ongoing, nationwide campaign to control carnivorous enemies of domestic livestock, as demanded by farmers and ranchers and promoted by the Biological Survey. Inherited from army and civilian park management, the programs attained legal justification through the Organic Act's authorization to destroy animals considered "detrimental to the use" of parks. Determined to keep the national parks unimpaired, the Service acted as though the predators themselves were impairments-threats to be dealt with before they destroyed the peaceful scenes it wished to maintain. Mather believed predator control helped increase the populations of the "important species of wild animals," and he once stated that the national parks offered sanctuaries to all wildlife "except predatory animals." Shortly after he succeeded Mather, Horace Albright defined predators as those species that preyed on "animals that add so much to the pleasure of park visitors""-clearly tying predator reduction to public enjoyment. Albright saw predator control as a means of protecting those "species of animals desirable for public observation and enjoyment," and declared that the "enemies of those species must be controlled."