Rock stacking's hidden consequences: How a popular trend harms mountain wildlife

ASHEVILLE, N.C. (WLOS) — Every year, millions of people flock to Western North Carolina to experience the mountains' bounty of national parks, forests, and outdoor recreation.

As you spend time outdoors, you might come across curious towers of rocks near waterways or trails. Appearing in a variety of sizes, they're always made by human hands. Maybe you've even been the architect of one of these stone stacks a time or two.

Although it may seem harmless, environmental experts and park employees say moving rocks around can have devastating consequences for forest wildlife.

A stacking problem

Rock stacks - sometimes called cairns - serve a purpose in some parks where they're used as trail makers for hikers. Outside of this, the reasons people stack rocks can vary from meditation, art, or a simple photo opportunity.

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"I just feel like people love to interact with nature in all different ways," David Gillette, a professor of environmental studies at UNC Asheville, said. "When I was a kid, I'd play in the creek, and I'd move rocks around and stuff, and there's probably no problem on a really small scale."

However, Gillette points out that the ecosystem gets disturbed when hundreds of forest visitors start moving rocks around.

Lori Williams, a wildlife diversity biologist with the North Carolina Wildlife Resources Commission, does species conservation work in the mountains. She says rock stacking rose in prominence about 10 years ago and continues to be a problem, especially where recreation is concentrated, like Pisgah National Forest and Nantahala National Forest.

"It is a growing problem, made worse by social media and the huge increase in the number of visitors we are seeing in our mountain rivers and streams," Williams said.

The issue can reach a fever pitch around major summer holidays when thousands of people gather at a relatively small stretch of river.

"We're not talking about skipping a pebble with your child -- we are talking about moving large boulders and cobble-sized rocks around for the purpose of building dams, or tube chutes, or to build elaborate stacks, just to get a photo for social media," Williams said.

Cairns are not only found by water's edge. In DuPont State Recreational Forest, Forester Jordan Luff says rock stacks show up at rock outcrops -- areas of exposed rock with no soil or vegetation on the mountainside. He says visitors will use flat "dinner plate"-like stones at these rock outcrops to construct stacks.

"They'll stack rocks for whatever reason, be it cultural or social, and they kind of put them in places where other people will see them," Luff said.

When these stacks are discovered, Luff and his colleagues work quickly to dismantle them.

"If one person sees it, then they may replicate that behavior, and we'll start to get more and more rock stacks like that," Luff said.

Hidden consequences

As eye-catching as rock stacks can be, their impact on wildlife may go unseen by most.

One species that is especially affected by the movement of rocks is the eastern hellbender -- a large, aquatic salamander that spends most of its life under large, flat stones that shelter them.

Professor Gillette said he and his students conducted a study of hellbenders in the Mills River and found the creatures have particular requirements for the rocks they'll use for shelter and nesting.

"So, when we start moving those rocks around, especially if it's the breeding season, we might be negatively impacting the ability of that species to breed for the year because they only breed for a month or so during the year," Gillette said.

Williams adds that if an active hellbender nest rock is disturbed, eggs can get washed out and eaten by predators.

"It could have a negative effect on the population if nesting habitat is constantly disturbed," she said.

Sadly, the impact of manipulating river rocks can have more immediate impacts. Williams shared images of adult and baby hellbenders found crushed to death as a direct result of nearby rocks that were moved.

"People don't realize they are not the only ones in the river," Williams said.

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Gillette says other salamander species move back and forth from the stream to the land and depend on stones along the shore for protection.

"You can imagine if those rocks are moved around one day they come out, all of a sudden the predators could really have an impact on them," he said.

Great Smoky Mountains National Park has also highlighted the harmful effects of rock stacking in a Facebook post that's been shared over 10,000 times. The post shows how one rock used to make a cairn had caddisfly larvae that were dried up and unable to move because it was pulled from the water.

The river chub, a small fish, piles up small rocks to create mounds during mating season, Gillette says. These rock piles are also used by other fish species that spawn there.

"If those were disturbed, you know, it would affect the ability of that species to breed for that year," Gillette said.

Moving and stacking rocks is more than a problem for aquatic life. Forester Luff says the flat stones found at DuPont State Forest's rock outcrops are an essential habitat for a variety of animals, including lizards, rattlesnakes, copperheads, and eastern small-footed bats.

"The small-footed bat being a particular species of concern that use those dinner plate rocks that get used in rock stacking a lot. That's really crucial habitat for them in the summer months," Luff said.

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Leave no trace

The "leave no trace" philosophy encourages outdoor visitors to preserve the land for the future. Luff says it goes beyond picking up trash or cleaning campsites -- it's about leaving as little impact as possible and setting a good example for others.

"Leave this place better than you found it, because there's going to be a million people that come in behind you," he said. "What you do will be replicated by the people that are watching you."

Williams says "leave no trace" is well-known among campers and backpackers — the N.C. Wildlife Resources Commission is now trying to convey that message to river users.

"Your actions matter," she said. "We want people to appreciate and enjoy, but be good stewards of, the gift that is our mountain rivers and streams."

Experts encourage folks to enjoy the outdoors this summer, but keep in mind that a vibrant world of wildlife is living in the streams and land they walk across.

"When you look at the ecosystem around you, just remember that it's evolved over thousands and thousands of years to support all the species that are there," Gillette said. "If you do cross a river, just be aware that there's lots of amazing diversity there that you might not be able to see."