Reduction of lions, wolves or cougars causes imbalance in the ecosystem. Predator shortage leads to overcrowding of herbivores.
The progressive disappearance of large carnivores, such as lions, wolves or cougars, threatens the planet's ecosystems, warned an international team of scientists who called for the protection of these predators.
More than 75% of the 31 species of these animals have been reduced in population, and 17 of them are currently occupying less than half of their original territory, according to a study published in the January 10 issue of the journal Science.
Large carnivores have been largely wiped out in a large number of developed countries, particularly in Western Europe and the eastern United States. And this hunt still extends to various parts of the world, scientists have criticized. However, they cautioned that these animals appear to play a crucial role in maintaining the delicate balance of ecosystems.
"On a planetary scale we have lost our great carnivores," said William Ripple, a professor in the department of forest ecosystems at Oregon State University and lead author of this study.
"Several of these animals are threatened as their territories shrink rapidly. And most of them are in danger of extinction, locally or globally," Ripple warned, "paradoxically that these species disappear at a time when we are becoming aware of their importance." maintaining the ecological balance ".
These American, European and Australian scientists say it is time to launch a worldwide initiative to reintroduce these animals into the wild and reconstitute their populations, citing the so-called "Large Carnivore Initiative" in Europe. This initiative aims to introduce
To develop their scientific work, Ripple and his colleagues focused on seven species whose impact on the ecosystem has been the subject of much study. They are the African lion, the European lynx, the leopard, the gray wolf, the cougar, the sea otter and the Australian dingo.
These surveys show that a decrease in the population of cougars and wolves in Yellowstone parks in the United States has led to an increase in the number of animals that feed on tree leaves and shrubs such as deer. This phenomenon disturbs the growth of vegetation and affects birds and small mammals, the scientists explained.
In Europe, the disappearance of lynx has been linked to overcrowding of bucks and hares, while the disappearance of large numbers of lions and leopards in Africa has caused an explosion in the number of olive baboons, which destroy crops and attack herds.
Finally, the decline in Alaska's otter populations has led to a strong growth of sea urchins and a reduction in brown seaweed from which they feed.
"Nature is interdependent, as these studies indicate in Yellowstone and around the world. They reveal how one species affects other species in different ways," and the ecosystem as a whole, Ripple added.
Thus, avoiding overcrowding of herbivores allows the flora to develop further and store more carbon dioxide, the main greenhouse gas, which would better combat global warming.
But the authors of this study admit that it will be very difficult to make people accept the large-scale reintroduction of these predators.
These animals inspire fear in humans, who have long declared war on them to protect their livestock and their communities, they explained. As a result, American wildlife groups failed to oppose the lifting of federal wolf protection in Montana and Idaho in 2011, a measure that was followed in 2012 by Wyoming under pressure from ranchers.