NEW DELHI: Large predators such as lions, bears, wolves, dingoes and otters are declining across the world driven by habitat loss, persecution by humans and loss of prey, an analysis of 31 large carnivore species published today in the journal Science shows.
More than 75 percent of the 31 species are declining, and 17 species now occupy less than half of their former ranges, the study reported. Decline in predators means a simultaneous increase in their prey, which causes devastation of the ecosystem.
Southeast Asia, southern and East Africa and the Amazon are among areas in which multiple large carnivore species are declining. With some exceptions, large carnivores have already been exterminated from much of the developed world, including Western Europe and the eastern United States.
"Globally, we are losing our large carnivores," said William Ripple, lead author of the paper and a professor in the Department of Forest Ecosystems and Society at Oregon State University. "Many of them are endangered," he said. "Their ranges are collapsing. Many of these animals are at risk of extinction, either locally or globally. And, ironically, they are vanishing just as we are learning about their important ecological effects."
The researchers reviewed published scientific reports and singled out seven species that have been studied for their widespread ecological effects. This includes African lions, leopards, Eurasian lynx, cougars, gray wolves, sea otters and dingoes.
Ripple and his Oregon State co-author Robert Beschta have documented impacts of cougars and wolves on the regeneration of forest stands and riparian vegetation in Yellowstone and other national parks in North America. Fewer predators, they have found, lead to an increase in browsing animals such as deer and elk. More browsing disrupts vegetation, shifts birds and small mammals and changes other parts of the ecosystem in a widespread cascade of impacts.
In some parts of Africa, the decrease of lions and leopards has coincided with a dramatic increase in olive baboons, which threaten farm crops and livestock. In the waters off southeast Alaska, a decline in sea otters through killer whale predation has led to a rise in sea urchins and loss of kelp beds.
"Human tolerance of these species is a major issue for conservation," Ripple said. "We say these animals have an intrinsic right to exist, but they are also providing economic and ecological services that people value."
Among the services that have been documented in other studies are carbon sequestration, riparian restoration, biodiversity and disease control.
Ripple and colleagues from the United States, Australia, Italy and Sweden called for an international initiative to conserve large predators in coexistence with people. They suggested that such an effort be modeled on the Large Carnivore Initiative for Europe, a nonprofit scientific group affiliated with the International Union for the Conservation of Nature.
Source: Times of India, January 10, 2014