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Top predators constrain mesopredator distributions. Newsome TM, Greenville AC, Ćirović D, Dickman CR, Johnson CN, Krofel M, Letnic M, Ripple WJ, Ritchie EG, Stoyanov S, Wirsing AJ.Nature communications. 2017 May
Top predators can suppress mesopredators by killing them, competing for resources and instilling fear, but it is unclear how suppression of mesopredators varies with the distribution and abundance of top predators at large spatial scales and among different ecological contexts. We suggest that suppression of mesopredators will be strongest where top predators occur at high densities over large areas. These conditions are more likely to occur in the core than on the margins of top predator ranges. We propose the Enemy Constraint Hypothesis, which predicts weakened top-down effects on mesopredators towards the edge of top predators’ ranges. Using bounty data from North America, Europe and Australia we show that the effects of top predators on mesopredators increase from the margin towards the core of their ranges, as predicted. Continuing global contraction of top predator ranges could promote further release of mesopredator populations, altering ecosystem structure and contributing to biodiversity loss.
By Emily Schwing
Wolves mostly make the news when they are in conflict with livestock and that’s part of the reason they were once removed from the Western landscape. But a new study shows wolves play an important role, whether we like it or not.
It’s not just wolves that prey on livestock.
“Worldwide, smaller meso-predators like coyotes, jackals and such, actually themselves prey pretty heavily on livestock and can cause a lot of economic damage,” Aaron Wirsing of the University of Washington said.
Wirsing co-authored a new study in the journal Nature Communications. He said current land management policies don’t offer apex predators enough space, but that doesn’t mean he wants to see wolves roaming rampant across North America.
“We need to allow predators to occupy more landscapes than just remote, protected areas,” Wirsing said. “On the other hand, we also need to heavily manage them, recognizing that they do conflict with people.”
That conflict made headlines last summer, when members of the Profanity Peak wolf pack killed four calves in Northeastern Washington. In response, Washington’s Department of Fish decided to shoot members of that pack from a helicopter.
“Historically, our model has been almost a postage stamp model where we protect certain areas and try to maintain intact assemblages of animals,” Wirsing said. “But we have a problem of scale.”
So, for example, areas protected for wildlife and public use might seem large from a human perspective, but what humans ay not consider is wolves can range up to 1,000 miles.
And it’s not only in the forest. Wirsing said wolves also roam the sage brush landscape in the central Northwest.
The study made use of bounty hunting data to show ecosystems function similarly in both Europe and Australia as well.