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“The two factors — small incremental changes in temperature or abrupt weather events — increase the risk of local extirpation or extinction.”

In either scenario, some species will need a bigger range and connected habitat to increase their likelihood of success as a species.

But some wildlife populations are more isolated due to forest fragmentation from development, land use patterns and roadways.

“The pinch point is here in the Southern Appalachians,” she said.

And nowhere is that more evident than in the Pigeon River Gorge.

The section of Interstate 40 from Asheville to Knoxville, Tenn., angles on a south-to-north trajectory through the gorge. 

To the west is the 522,000 acres of Great Smoky Mountains National Park. To the east are relatively large, unfragmented sections of Pisgah National Forest in North Carolina and Cherokee National Forest in Tennessee.

The two sections of forest unite at a narrow neck like an hourglass, separated by four lanes of concrete running 28 miles from Fines Creek, N.C., to Hartford, Tenn. 

Researchers from the University of Washington and the Nature Conservancy modeled potential habitats and plotted movement routes for nearly 3,000 species of mammals, birds and amphibians using climate change projections and climatic needs of the species.

The resulting map shows colorful arrows representing creatures in motion. Species from Central America and Florida merge to form a channel in the Southern Appalachians.

Nikki Robinson, the North Carolina project manager of the Wildlands Network, said her organization has designated three “wild ways” in North Carolina. One of them, along the East Coast, includes a connected network of natural areas that span the Eastern Seaboard.

“We really emphasize the importance of collaboration and communication among state and federal agencies, other nonprofit organizations and the residents of these communities to ensure locally led solutions will support these communities that they’re that we’re serving,” she said. 

Yet connecting natural areas, Hillard explained, is a bit like piecing together a jigsaw puzzle.

“These big animals really need to roam and have large home ranges to access resources available at different times of year but also to (respond to) weather events that influence availability of food and habitat,” she said.

 The elk movement study is part of a comprehensive examination conducted in the Pigeon River Gorge that was designed to better understand animal behavior patterns in order to pinpoint wildlife-vehicle collision hot spots.  The project collected collision data from law enforcement and weekly surveys to detect “roadkill.” In addition, they used dozens of wildlife cameras along the roadway to monitor existing structures on I-40, such as bridges and culverts.

Those findings will identify where to enhance infrastructure on I-40. 

Hillard’s research demonstrated that elk, black bears and deer interact with the roadway. She thinks the road creates a barrier effect for animals but admits that understanding wildlife behavior can be perplexing. 

For example, she’s observed animals using the roadway but not crossing it. On the other hand, over three years, she observed female elk boldly crossing the interstate to give birth in the national forest and returning to the national park with their calves.

However, among the meaningful findings of the research is that vehicle collisions are more likely to occur near bridges and culverts. Daily, 26,000 vehicles pass through the gorge.

The extreme topography of the gorge, she said, funnels wildlife to the roadway.

“We’ve put our roadways along the path of least resistance, which is also where wildlife want to move,” she said.  “The water, the landscape, the topography shape how these elk move. They like to follow valleys and the paths of least resistance just like humans.”

Estimates say more than 1 million large animals are killed annually in collisions with vehicles in the U.S. Large creatures, however, are not the only animals impacted by I-40: Aquatic animals and amphibians are also a concern.

And, of course, humans are hurt, too. 

According to the National Highway Traffic Safety Administration, about 200 die every year in animal-vehicle collisions. The average cost of a deer-car collision is $8,190; elk-vehicle collisions exceed $25,000 per crash, according to a paper from the Western Transportation Institute at Montana State University.

This summer the Wildlands Network will publish a statewide report identifying the top 20 wildlife-vehicle collision hot spots in North Carolina, six of which are in the state’s western counties, despite a lower human population density.

Some existing structures in the gorge seem to help facilitate safe passage for wildlife. For example, lower mortality rates and evidence from cameras suggest animals are using a bridge over Jonathan Creek. Black bears are also passing through three culverts near Groundhog Creek. In addition, the current replacement of a bridge at Harmon Den adopted features to ensure safe passage for wildlife and automobiles.

In those places, Hillard believes, adding fencing or other structures to funnel animals to safe passage is an efficient and relatively low-cost solution to facilitate safe wildlife crossings.

Yet, at the top of Hillard’s wish list are two wildlife overpasses — one in Tennessee; one in North Carolina — like an existing wildlife overpass on I-90 in Washington state.

Essentially, it would be a greenway for wildlife to move above the fray of speeding semis and automobiles.

Bridges, of course, aren’t cheap. But Hillard is hopeful there are future funding opportunities, such as the Bipartisan Infrastructure Law that coincides with the urgency to replace aging bridges and structures along the interstate system.

“We think our project is supported by strong research and data that support where these mitigation opportunities are,” she said. 

“I think an iconic structure will represent the importance of what wildlife and connected landscapes mean for us in the region.”