The decline of large carnivores such as lions, wolves or pumas is threatening the Earth’s ecosystems, scientists warned as they launched an appeal to protect such predators.

More than 75 per cent of 31 large carnivore species are declining, says a study published in American journal Science and dated January 10.

“Globally, we are losing large carnivores,” wrote William Ripple, lead author of the study and a professor in the Department of Forest Ecosystems and Society at Oregon State University.

“Their ranges are collapsing,” Ripple wrote.

“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 American, European and Australian scientists who took part in the study said it was time to launch a worldwide initiative to reintroduce these animals into the wild and restore their populations.

Ripple and his colleagues focused on seven species that have been studied for their widespread ecological effects: African lions, leopards, Eurasian lynxes, cougars, grey wolves, sea otters and dingoes.

Reports show that a decline in pumas and wolves in Yellowstone National Park led to an increase in animals that fed on tree leaves and bushes, such as deer and elk. This disrupted the growth of vegetation and shifted populations of birds and small mammals, the researchers said.

In Europe, fewer lynx have been tied to overpopulation of roe deer, red foxes and hares, while in Africa the disappearance of lions and leopards has coincided with a dramatic increase in the number of olive baboons, which threaten farm crops and livestock.

“Nature is highly interconnected,” said Ripple. “The work at Yellowstone and other places shows how one species affects another and another through different pathways.”

For instance, avoiding overpopulation of herbivores allows forest flora to develop more and sequester more carbon dioxide, the main greenhouse gas responsible for global warming.

But the study’s authors say it will be hard to convince people to accept a large-scale restoration of large carnivore populations.

People are afraid of them and have fought them to protect their livestock and their communities, they said.