Carnivores at risk: An essay describing the challenges and importance of conserving carnivores
Luke Hunter, PhD
President and Chief Conservation Officer
Mammalian carnivores are difficult to conserve. Firstly, they are naturally rare. All species that survive by eating others are automatically less abundant than their prey. Every lion needs about 50 medium or large ungulates a year to survive. In naturally functioning ecosystems, that represents about 10% of available prey; that is, a population of 500 prey animals is required to sustain a single lion for a year. Therefore, a single pride of 10 lions requires 5000 prey animals (not accounting for the needs of coexisting carnivores such as cheetahs, leopards, hyaenas and African wild dogs) which, in turn, require large expanses of habitat to survive. If lions ate grass, they would be as common as wildebeest or zebras.
The combined loss of habitat and prey is the main threat to most carnivores today. Over two-third’s of the earth’s terrestrial land area is now devoted to supporting people with the remaining natural habitat disappearing at an estimated rate of 1% per year. Where people replace forest, woodlands and grasslands with cities, agriculture and livestock, most carnivores decline or disappear. Even maintaining habitat is valueless if there is no food for carnivores. Tracts of relatively intact but ‘empty forest’ across Asia, Latin America and central Africa are worthless to carnivores because people have hunted out the prey on which they depend.
Aggravating the ongoing depletion of resources on which carnivores depend- indirect threats, in conservation nomenclature- are the reasons why people kill them intentionally. Today, people persecute carnivores for two key reasons- because carnivores are considered a threat to livestock (and, less so, to human life), and because their body parts are considered valuable. The former affects large carnivores wherever they encounter people and their herds, from subsistence shepherds in Central Asia that trap snow leopards, to commercial cattle ranchers in the Western United States that clash with reintroduced grey wolves. The killing of carnivores for their parts occurs globally but is particularly problematic in Asia where the consumption and use of wildlife for ‘traditional medicine’ has a history of thousands of years. Not surprisingly, these two drivers are often interleaved; Mongolian herders make extra money by selling the furs of sheep-killing wolves (or any they can shoot, for that matter) and the claws, fat and other sought-after parts of lions poisoned by African pastoralists are often sold or traded.
Although not nearly as widespread, ancillary anthropogenic threats to carnivores can be locally damaging to populations. Recreational hunting, whether by big game hunters for trophies or by trappers for fur-bearing carnivores, can provoke declines where poorly regulated or in concert with other factors, for example, natural fluctuations in prey numbers. Infectious disease is a natural part of wildlife populations worldwide but it can be particularly problematic to carnivores when introduced by people and their domestic animals. Wild canids are especially vulnerable to rabies and canine distemper transmitted by domestic dogs, and outbreaks have devastated populations of Ethiopian wolves and African wild dogs. Finally, a handful of species are threatened by hybridisation with domestic carnivores; the genetic distinctiveness of the Wildcat and the Dingo is imperiled by interbreeding with feral domestic cats and dogs respectively.
Today, four modern carnivore species are extinct as a direct result of human impacts, primarily hunting (with the last record in parenthesis); the Falkland Island Wolf Dusicyon australis (1876), Sea Mink Mustela macrodon (1894), Japanese Sea Lion Zalophus japonicus (1951) and Caribbean Monk Seal Monachus tropicalis (1952). Eight carnivores (including two pinnipeds) are Critically Endangered with an extremely high risk of extinction in the wild. 24 carnivores (including four pinnipeds) are Endangered with a high risk of extinction.
Carnivore declines and local extinctions are not only tragic from the view of species conservation, they can produce effects that reverberate across entire ecosystems. Carnivores play an important role as ecosystem engineers, with significant effects on herbivore populations. Moreover, carnivores include iconic species like the lion or tiger that help generate important funding for biodiversity conservation, and deliver important benefits to humans. Scientists recently calculated the consequences of reintroducing cougars into the northeast United States where the species is now extinct. They found that, within 50 years of successful establishment, cougars would likely reduce deer densities and thus vehicle collisions with deer by 22 percent. That results in 53,000 prevented human injuries, 384 prevented human fatalities, and $4.41 billion in avoided costs. Conserving carnivores translates to saving thousands of other species, including people.
As many countries are currently wrestling with the challenges of expanding their protected area network, we wanted to understand the future of carnivores in this process. Specifically, our research aimed to identify where the priority areas for carnivore conservation occur, and how effectively these areas would be in protecting carnivores, and many other species, 25 years into the future.
(text modified from A Field Guide to Carnivores of the World by Luke Hunter)