In ecosystems around the world, the decline of large predators such as lions, dingoes, wolves, otters, and bears is changing the face of landscapes from the tropics to the Arctic -- but an analysis of 31 carnivore（食肉动物） species published today in the journal Science shows for the first time how threats such as habitat loss, persecution（迫害，烦扰） by humans and loss of prey combine to create global hotspots of carnivore decline. More than 75 percent of the 31 large-carnivore species are declining, and 17 species now occupy less than half of their former ranges, the authors reported.

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."

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.

The researchers reviewed published scientific reports and singled out seven species that have been studied for their widespread ecological effects or "trophic cascades." 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.

Studies of Eurasian lynx, dingoes, lions and sea otters have found similar effects, the authors reported.