Why Are Carnivores So Important?
Carnivores are crucial in regulating and maintaining ecosystems. Larger carnivores in particular are often keystone species, meaning that they play a disproportionately greater role in the health of their ecosystem than you would expect based on their numbers. Through hunting, carnivores maintain herbivore populations at a healthy level, preventing an overabundance of herbivores and thereby protecting vegetation from being too heavily grazed or browsed. That in turn protects other plant and animal species that depend on a healthy vegetation assemblage for food or shelter.
A commonly cited example of the importance of larger carnivores is the gray wolf in the Yellowstone Basin ecosystem in Wyoming. Wolves were eradicated from the area in the early 20th century to protect livestock in neighboring grazing lands. Without the pressure of predation by wolves, the number of elk (the wolf’s primary prey) increased dramatically. The result was a cascade of ecological damage: the over-abundance of elk led to over-browsing of aspen trees; smaller tree and shrub species associated with aspen forest declined; and several mammal and bird species that depended on those plant species for food and shelter disappeared. When wolves were reintroduced to Yellowstone in the late 20th century, they reduced elk numbers to a sustainable level, allowing the aspen and associated plant species to regenerate and enabling the return of mammals and birds that had long been absent from the ecosystem.
In mainland Australia, the dingo plays a similarly crucial ecological role, keeping kangaroo populations in check and thereby preventing over-grazing that would have a negative impact on both plant and animal communities. In addition, dingoes apply pressure on two invasive predators, the fox and feral cat. In areas where dingoes are controlled because of their potential predation on livestock, fox and feral cat numbers increase, and small and medium-sized native mammal species suffer as a result.
Collectively, the three largest native carnivores in Tasmania — the Tasmanian devil, spotted-tailed quoll and eastern quoll — are believed to play a similar role in controlling invasive predators and thereby preventing the sort of small mammal extinctions that have occurred on the mainland.
Gray wolf: Photo by Tracy Brooks (U.S. Fish & Wildlife Service) [Public domain], via Wikipedia Commons.
Dingo: Photo by Christopher Watson (http://www.comebirdwatching.blogspot.com/) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons.