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Outdoors
Smoky Mountain News
Symbolic of the risk–reward situation that bears must face when there is a critical need for them to search for food, security, dispersal or breeding, a female bear looks for the best opportunity to cross as her cubs surround her at the guardrail on I-64 in Virginia near the top of Afton Mountain where the Shenandoah National Park and the Blue Ridge Parkway meet. Bridget Donaldson, Virginia Transportation Research Council photo
Plans for safe passage Research yields recommendations to stem wildlife deaths on I-40 BY HOLLY KAYS OUTDOORS EDITOR fter more than three years of research and analysis, a group focused on ending wildlife-vehicle collisions in the Pigeon River Gorge has released a report outlining its
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recommendations for keeping them safe from traffic. “Here is a document that serves as longterm planning document for both the Tennessee and North Carolina Department of Transportation, and thankfully they’re both fully engaged and energized by this work,” said Jeff Hunter, senior program manager for the National Parks Conservation Association. “Can we do everything? Can you do everything in any endeavor? Perhaps not, but at least now we have an evidence-based
A visualization from the report shows wildlife death and detection rates through the Pigeon River Gorge. Wildlands Network/NCPA graphic
approach to mitigating wildlife-vehicle collisions in this nationally significant landscape adjacent to the Great Smoky Mountains National Park.” The recommendations released last week were the result of research funded by Safe Passage: The I-40 Pigeon River Gorge Wildlife Crossing Project and completed by NCPA and Wildlands Network. The 86-page report explains the results of the multi-faceted research effort required to understand how many animals are dying during road crossings, where those crossings are occurring and how existing road structures correlate to success in safely navigating the gorge. The research focuses on large animals — specifically bear, deer and elk — because they are easiest to study and pose the most danger to human motorists.
THE RESEARCH The research area is a 28-mile portion of Interstate 40 that parallels the Pigeon River and is often bordered by sheer rock walls on the opposite side. The entire area is a wildlife hotspot, with the road cutting through an otherwise remote region that’s home to the Great Smoky Mountains National Park, Pisgah National Forest and Cherokee National Forest. To find out how wildlife use the area, researchers set up a series of camera traps. They established 66 wildlife cameras to monitor 33 400-meter road segments — choosing only segments that did not contain a continuous cut rock cliff — and also set up cameras at 21 roadway structures such as bridges and culverts. Additionally, they fit 13 elk with GPS collars to better understand their movement patterns. Meanwhile, they sought to understand the magnitude of the wildlife mortality problem. To do this, they compiled information about wildlife deaths contained in crash report data
Top priority Years of research have informed the following list of highest-priority wildlife road crossing projects recommended for the Pigeon River Gorge.
North Carolina projects: 1. Wilkins Creek Overpass: Construct an overpass over I-40 between Wilkins Creek Box Culvert A and the NCDOT Rest Area. Pursue land acquisition or conservation easements to stabilize the area for wildlife. 2. Single Tunnel Overpass: Construct an overpass extending the existing Single Tunnel land bridge across the rest of I-40. 3. Cold Springs Creek Exit Culverts: Replace the existing culverts on both the entrance and exit ramps with larger structures to facilitate better terrestrial and aquatic wildlife passage. 4. Groundhog Creek: Replace the three small existing culverts with a larger structure suitable for all target species. Tennessee projects: 1. Waterville Bridge: Add a wildlife-friendly shoulder along the underpass road when the bridge is replaced and consider a future wildlife and pedestrian overpass in this area. 2. Naillon Branch: Replace the existing culvert with a larger structure suitable for all our target species or construct an elkfriendly overpass. Pursue land acquisition or conservation easements to stabilize the area for wildlife. 3. Laurel Hollow: Replace the existing culvert with a larger structure (culvert or small bridge) suitable for all our target species. for 2001-2020. Then from September 2018 through December 2021, researchers conducted weekly driving surveys to augment numbers obtained through crash data. Over the 20-year period, researchers recorded 336 incidents of wildlife-vehicle collisions, and all indications are that this is an undercount. In 2020, for example, researchers documented 50 wildlife-vehicle collisions — but only one of those was reflected in agency crash reports. “We could talk about numbers all day,” said Hunter. “The fact of the matter is we know we have a problem.” Of the 336 dead animals, 304 records contained enough information for further analysis. Of the 304, the largest number — 55% — were bear, this despite the fact that deer was the most-recorded species on the 66 roadside cameras, accounting for 78% of sightings. Of the cameras set up at the 21 road structures, 86% detected one or more of the target species, with 76% detecting deer, 67% bear and 19% elk. “I think one of the really interesting findings is that a lot of our mortality is associated with the existing structures,” said Hunter. “It was somewhat counterintuitive until we started peeling back the layers.”
