Utilitarian conservation attempts to minimize or eliminate populations of species that are viewed as pests because they cause economic damage or threaten the health and safety of people or domesticated organisms. People disagree about what constitutes a pest. Pigeons, English sparrows, wolves, tigers, and many other organisms inspire strong positive and negative feelings. Pest control is most acceptable if it is non-lethal and has little effect on non-target species. Integrated pest management strives to use biological pest control, habitat manipulation, and education to maximize the efficiency of pest control. Historically, predators were targeted by government control programs including bounties, but Aldo Leopold changed his attitude about wolves in the influential essay Thinking Like a Mountain. Human behavior toward dangerous animals such as bears may exacerbate pest problems.