Carnivores modulate prey populations and make them more vigorous. Carnivores increase biological diversity and functionality of those systems, and rarely overcome their prey populations. By modulating deer populations, mountain lions prevent overgrazing near fragile riparian systems. The result: more cottonwoods, rushes, cattails, wildflowers, amphibians, lizards, and butterflies, as well as deeper but narrower stream channels. In short, when large-bodied carnivores are present, there is greater biological diversity and greater ecosystem function.
Yet, large-bodied carnivores are facing increasing threats to their very persistence and survival. Conservation biologists have warned that large terrestrial carnivores have declined by 95 to 99% from their habitats around the world and in North America. We are just coming to understand how important they are, just as we are wiping out their remaining populations.