Compared to the 18th and 19t centuries, the current North American range of gray wolves has declined by 42.3 percent. (Wang Jiayi/The Epoch Times)
“We are seeing that there are interconnections in nature that are important. When we disrupt the interconnections, when we lose our top predators, it can affect the other parts of the ecosystem,” said Dr. William Ripple, professor of forest ecosystems and society at Oregon State University.
Ripple and his colleagues found that since all of the largest terrestrial predators in North America have been in decline for the last 200 years, the geographic ranges of 60 percent of mesopredators have expanded.
Compared to the 18th and 19th centuries, the current North American range of gray wolves has declined by 42 percent, likely contributing to the 40 percent range increase for coyotes and 18 percent increase for raccoons, according to the study.
“Top predators are not tolerated by humans as much as other animals. And there’s a long history of humans persecuting large predators. For example, there’s a history of humans persecuting wolves throughout the world.
“In the United States, where we lost wolves, we have a huge increase in the number of coyotes. The coyotes prey on farmers’ sheep. That’s an example of just one cascading effect when we lose our top predators.
“Americans are very familiar with highly abundant raccoons, which might proliferate in our own neighborhoods,” said Ripple.
The problems are not confined to terrestrial ecosystems. Deep in the Atlantic Ocean, sharks are facing serious decline due to overfishing.
"As a result of the decline in sharks, we have an explosion of rays, which are smaller predators. This increase in rays collapsed the bay scallop industry, constituting both an ecological and economic loss,” said Ripple.
The rise of mesopredators—in a good number of North Americans’ eyes—is only as serious as needing to be more vigilant of raccoons or eating fewer bay scallops. But in Africa, mesopredator proliferation is barring some children from education.
In parts of Sub-Saharan Africa, “children are being kept at home from school to guard their family gardens against crop-raiding baboons. The baboons are eating their garden crops,” said Ripple. The huge surge of baboons is likely due to a decline in population of their predators—lions and leopards.
Collaborators on the BioScience article included researchers from Oregon State University, the University of California at Berkeley, and New Mexico State University at Las Cruces.
