Top predators (other than humans) are absolutely essential for the maintenance of ecosystems - be they terrestrial, aquatic or marine. When predators are absent - which is nearly always the case in the human dominated world - plant and smaller animal communities spiral out of control. Such chaotic plant and animal communities lead to unstable ecoystem composition, and is not sustainable. We must learn to live with all of Earth's species. And if we lose an occasional cow or even human life because of it, this is the cost of global ecological sustainability.

Without Top Predators, Ecosystems Turn Topsy-Turvy

...a classic cautionary tale of the dangers of removing top predators from an ecosystem. "Taking out predators has a cascade of effects on other populations, down to the plant life," said John Terborgh, a professor of environmental science at Duke University in Durham, North Carolina.