The catastrophic decline around the world of "apex" predators such as wolves, cougars, lions or sharks has led to a huge increase in smaller "mesopredators" that are causing major economic and ecological disruptions, a new study concludes.

The findings, published October 1 in the journal Bioscience, found that in North America all of the largest terrestrial predators have been in decline during the past 200 years while the ranges of 60 percent of mesopredators have expanded.

An example: in parts of Sub-Saharan Africa, lion and leopard populations have been decimated, allowing a surge in the "mesopredator" population next down the line, baboons. In some cases children are now being kept home from school to guard family gardens from brazen packs of crop-raiding baboons.

"This issue is very complex, and a lot of the consequences are not known," said William Ripple, a professor of forest ecosystems and society at Oregon State University. "But there's evidence that the explosion of mesopredator populations is very severe and has both ecological and economic repercussions."

In case after case around the world, the researchers said, primary predators such as wolves, lions or sharks have been dramatically reduced if not eliminated, usually on purpose and sometimes by forces such as habitat disruption, hunting or fishing.

Many times this has been viewed positively by humans, fearful of personal attack, loss of livestock or other concerns. But the new picture that's emerging is a range of problems, including ecosystem and economic disruption that may dwarf any problems presented by the original primary predators.

"I've done a lot of work on wildlife in Africa, and people everywhere are asking some of the same questions, what do we do?" said Clinton Epps, an assistant professor at OSU who is studying the interactions between humans and wildlife.

"Most important to understand is that these issues are complex, the issue is not as simple as getting rid of wolves or lions and thinking you've solved some problem. We have to be more careful about taking what appears to be the easy solution."

The elimination of wolves is often favored by ranchers, for instance, who fear attacks on their livestock. However, that has led to a huge surge in the number of coyotes, a "mesopredator" once kept in check by the wolves. The coyotes attack pronghorn antelope and domestic sheep, and attempts to control them have been hugely expensive, costing hundreds of millions of dollars.

"The loss of primary, or "apex" predators is causing an explosion in secondary, or "mesopredators" around the world, a new study concludes. In this image, the extermination of wolves may allow coyote populations to surge, which in turn can suppress feral cat populations, leading to more rodents, etc. These cascading effects are poorly understood but are causing ecosystem disruptions around the world, scientists say."

Source: Oregon State University