Mountain lions, too, have become locally overabundant. In the 1990s, California voters passed an initiative that protected the endangered mountain lion but contained no provisions for managing the lion if it became overabundant, unless it threatened human life and property. Few people thought the mountain lion could ever recover enough to become a problem, but in several cases in recent years mountain lions have attacked and even killed people.
Current estimates suggest there may be as many as 4,000 to 6,000 in California. These attacks become more frequent as the mountain lion population grows and as the human population grows and people build houses in what was mountain lion habitat. Once again, we find that the human population problem underlies this environmental issue. At the heart of issues concerning wild living resources is the question of sustainability of species and their ecosystems.
One of the key questions is whether we can sustain these resources at a constant abundance. In general, it has been assumed that fish and other wildlife that are hunted for recreation, such as deer, could be maintained at some constant, highly productive level. Constant production is desirable economically because it would provide a reliable, easily forecast income each year.