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Large predators expand their range, says NC study



Alligators and seals appear on the beaches of Carolina, large white sharks patrol the coast and coyotes have become a nuisance from the mountains to the Outer Banks.

The sightings of these predators are still frightening enough to spread news. A study conducted by scientists at Duke University suggests that the renegade animals are not "lost" but simply return home – to places they occupied before humans hunted them hard.

And you're better off not getting a big alligator on a beach or coral reef as an anomalous sighting, "said Duke ecologist Brian Silliman, lead author of an essay published on Monday in Current Biology Magazine." It's not an outlier or a short-term blip , It is the old norm as it was before we pushed these species into hard-to-reach shelters on their last legs. Now they're coming back. "

Silliman Rachel Carson, associate professor of marine biology at Duke's Nicholas School of the Environment, and his colleagues have recently researched scientific articles and government publications, and found that nearly two dozen large predators ̵

1; the essay calls they "consumers" – expanded into new habitats

It turns out that alligators in the southeast, who were once most at home in fresh water, can tolerate saltwater as their numbers increase. Sea otters in California move in from open water Gray wolves and mountain lions expand their current range.Coyotes and bobcats venture out on beaches.Killer whales have been discovered in freshwater rivers.

These results challenge long-standing ecologists on studies of species whose numbers have been declining that these meatfres need very specific places to search and breed, the tower says. "It's not just Animal Channel stories, it's ecology lessons too, I believed them," Silliman said in an interview.

But now that many predators recover, they show remarkable resilience.

Other studies have documented climate change as a driving force for some species moving north and to higher altitudes. But neither the climate nor the lack of competition for the prey of other predators fully explain the expansion into new territory, according to Duke's study.

Many predators migrate to places less hospitable to these predators. The researchers note that many large "consumers" such as black bears and coyotes can adapt very well to new types of prey and habitats.

"They colonize harsher environments," Silliman said. "Is it the case that animals go there for the first time? Probably not."

There are environmental benefits for predators recovering their old favorite places, notes the essay. Sea otters returning to the seagrass beds in estuaries feed on crabs, which in turn eat sea snails that eat algae. In this way, the otters indirectly keep the algae from suffocating the seaweed.

What does the proliferation of predators into their ancient territories mean for the people who live there? That they can coexist when people change old attitudes that turn predators into boogeyman, Silliman said.

He pointed to Asheville, where the plethora of city bears made the beer crazy mountain town known as a bear city. Bear observations are so common there that the inhabitants make video recordings rather than rifles. Most residents are wary of placing bird feeders or garbage cans where they are likely to attract bears.

"The acceptable behavior of predators and humans must change," said Silliman. "There will be conflicts, but it can be reduced by politics and new behaviors."

Silliman's co-authors were Lindsay Gaskins, Qiang He, and Andrew Read of Duke; Brent Hughes of the University of California Santa Cruz; Tim Tinker of UCSC and the US Geological Survey; James Nifong of Kansas State University; and Rick Stepp from the University of Florida. The funding came from the Stolarz Foundation, the National Science Foundation, a David H. Smith Conservation Fellowship, the US Geological Survey and the California Coastal Conservancy

Bruce Henderson: 704-358-5051; @bender


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