In an attempt to make the world realise what significant roles carnivores play in keeping a balance in our ecosystem, scientists have pointed out the current state of world's largest and the critical benefits they provide.
The research was conducted by a team of leading scientists, including Dr. Joel Berger of the Wildlife Conservation Society and University of Montana.
Among their many impacts, carnivores are a benefit to ecotourism.
Yellowstone National Park's restored wolf population, for example, brings in tens of millions of dollars in tourist revenue each year. And when wolves are absent, the effect on natural selection is dramatic.
WCS Conservation Scientist and author of 'The Better to Eat You With', Berger explained that in Badlands National Park, they have observed bison born with deformed hooves or portions of their legs missing, and historically, these bison would have been selected out for predation by wolves, contributing to the overall health of the herd.
Today, without wolves, these bison survive and reproduce and this is not the way healthy ecosystems are maintained, Berger said.
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The ecological services provided by carnivores are multifarious. Carnivores control herbivores to the relief of plants, mitigate global warming, enhance biodiversity, restore rivers and streams, and regulate wildlife disease and livestock disease spillover.
However, many of the largest carnivores are listed as threatened on the International Union for the Conservation of Nature Red List and most are still declining in number.
These 'top or apex predators' have one great competitor: humans.
The authors note that large-carnivore population declines are typically precipitated by multiple, and sometimes concurrent, human threats including habitat loss and degradation, persecution, utilization (such as for traditional medicine, trophy hunting or furs), and depletion of prey.
Oregon State University professor and lead author of the paper, William J. Ripple said that globally, the ranges of carnivores are collapsing and many of these species are at risk of either local or complete extinction.
"It is ironic that large carnivores are disappearing just as we are learning about their important ecological and economic effects," he said.
Looking to the future, the scientists expect that the loss of apex predators will bring degradation to ecosystems that include reductions in plant diversity, biomass and productivity as well as wide-ranging impacts to other species.
Greater rates of herbivory and concurrent decline of plant species may hasten global warming and desertification.
The study is published in the journal Science.