In a study of 31 carnivorous species, researchers at Oregon State University report that more than 75 percent of the large carnivores are declining, and 17 species now occupy less than half of their former ranges. The decline comes as a result of usual suspects habitat loss, human persecution and changing climate. What’s worse, the disappearance of carnivorous species could spell bad news for the ecosystems they occupy.

“Globally, we are losing our large carnivores,” said William Ripple, 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.”

Researchers see most of the decline in Southeast Asia, Africa and the Amazon, areas where humans still come in close contact with humans. In those areas, where farming and livestock play a big role in feeding the community, residents are quick to see predatory animals dangers, pests and threats to their livelihood and well-being. That makes getting the buy-in necessary for their conservation difficult.

“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.”

Indeed. Though the elimination of predators might bring humans benefits in the short-term, it doesn’t take long for their depletion to have serious implications on the ecosystems they help maintain.

Ripple and 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. They found similar effects in studies of Eurasian lynx, dingoes, lions and sea otters.

The studies prove that the age-old idea of predators depleting the numbers of fish and wildlife simply aren’t true. All components of an ecosystem need to remain in harmony for everything to remain stable, which ecologist Aldo Leopold asserted all the way back in 1948.If too many browsing animals are left unchecked, things like genetic diversity and disease control begin to suffer.

“Nature is highly interconnected,” said Ripple. “The work at Yellowstone and other places shows how one species affects another and another through different pathways. It’s humbling as a scientist to see the interconnectedness of nature.”

If there’s any good news, it’s that all is not lost. When conservations efforts have been able to restore carnivore populations (in Yellowstone National Park, for instance), the ecosystem showed astounding resiliency in its ability to fight back from the brink. The exceptions are places where things like soil erosion have occurred to to loss of vegetation from overly abundant grazing, which may never fully recover.

“I am impressed with how resilient the Yellowstone ecosystem is. It isn’t happening quickly everywhere, but in some places, ecosystem restoration has started there,” Ripple said.

African lions, leopards, Eurasian lynx, cougars, gray wolves, sea otters and dingoes were the seven species cited for having exceptionally catastrophic consequences when removed from an ecosystem.

Have you hugged a lion today?