As populations and outdoor recreation grows in the west it’s imperative that trail planning and management consider the effects of roads, trails, and recreation activities on big game high priority (and other) habitats. Although the detrimental impacts of motorized/mechanized roads and trails on big game have been extensively studied and well documented since the 1970s, during recent years some elk herds in Colorado, for example, are dying off as a result.
Multiple studies have clearly demonstrated that big game animals such as elk, mule deer, and bighorn sheep will avoid roads and trails and the human activities associated with them for up to 1/2 mile. Research has also demonstrated that avoidance is strongest in response to ATV use, followed by mountain biking, and is less strong in response to hiking and horseback riding.
Impacts from mountain bike trails is more severe when big game habitats are fragmented with high density loop systems that have greater than 1 mile of trail per section of land. Impacts from trails and recreation activity are greatest when they are located within big game high priority habitats such as concentration areas for winter range, production areas, and migration corridors and occur concurrently with seasonal big game use.
The Theodore Roosevelt Conservation Partnership (TRCP) estimates that 40 percent of Colorado’s most important elk habitat is affected by recreational trail use. As a result, it’s also recommended that trails planning and management adhere to the principals included in Colorado Parks and Wildlife’s (CPW) Planning Trails With Wildlife In Mind: https://cpw.state.co.us/state-trails-program (scroll down).
Nationwide, approximately 92 percent of all national forest lands lie within one mile of a road. Colorado’s national forests alone boast over 17,000 miles of roads and in the White River National Forest there are some 5,000 miles of system roads and trails. In the San Juan National Forest motorized road miles increased from 2,817 in the late 1990s to more than 6,400 miles in 2008. Across the state, there are nearly 40,000 total miles of mapped motorized and non-motorized trails. Some estimates suggest there exists an additional 25 to 30 percent of unmapped, user-created trails near popular mountain biking communities.
These numbers are staggering and their detrimental effect is clear: Increases in trail development/use in elk summer habitat near Vail (for example) corresponded to a nearly 50 percent decline in the elk population between 2001 and 2015. A Colorado State University (CSU) study performed in the Vail area observed that the elk calf-to-cow ratio plummeted by nearly 40 percent as a result of simulated recreation use in elk calving areas. With just over 8 disturbances per cow elk resulting in nearly 40 percent fewer surviving calves, each disturbance averaged nearly 5 percent probability of an elk calf dying.
Biologists used to count over 1,000 elk from the air near Vail, but when researchers flew the same area in February 2019 for an annual elk count they saw only 53. According to the Vail area Colorado Parks and Wildlife District Wildlife Manager (DWM), if trail building and closure violations in critical habitat continue, “It will be a biological desert.”
“I don’t think people realize the dramatic amount the elk population has decreased,” said former CPW District Wildlife Manager Craig Wescoatt. “We are not seeing the animals migrate to another area or permanently move somewhere else. They are just dead and gone.” Perry Will, a former CPW supervisor, said, “It’s not like the elk are moving somewhere else, they are just dying off.”
CPW District Wildlife Managers we talk to have repeatedly emphasized that the proliferation of motorized and mechanized trails (legal and illegal) is negatively impacting elk herds. Although many motorized and mechanized trail users will tell you they’re concerned about their impact on wildlands and wildlife, they never seem to advocate for identifying and closing illegal trail networks, which speaks volumes. In fact, some mechanized users and their advocacy groups quietly encourage the building of illegal trails on public lands.
“As I analyze a new area, the first thing I do is pull it up in my hunting app and study all access in and out. This includes roads, off-road routes and hiking trails,” American Hunter Field Editor Mark Kayser explains. “And with today’s invasion of e-bikes, I am also researching to see if they are allowed in the area. The fewer designated routes the better for increased possibilities of elk meetings.”[1]
“Every Colorado Parks and Wildlife DWM I talk to emphasizes that the proliferation of motorized and mechanized trails (legal and illegal) is negatively impacting elk herds,” Colorado Backcountry Hunters & Anglers co-chair David Lien emphasized.[2] As a result, Colorado BHA offers a $1,000 reward for reports or information leading to a conviction of those responsible for building illegal trails on public lands.[3]
For additional information about the damage being caused by the proliferation of legal and illegal trails on public lands see the “Resources” section below and these BHA Blog posts: “Trails vs. Elk: ‘They’re Just Dying Off’” and “Colorado Backcountry Hunters & Anglers Increase Reward For Illegal Trail Construction (Help Stop Trail Building ‘Free-For-All’).”
For more about the ongoing efforts by some legislators in Congress (and others) to privatize our public lands estate see the “Bad Ideas” sections in these BHA Blog posts: “6x6 Karma: The Bear Facts” and “A Hunter-Angler (Hell-Raisin’ & Habitat Savin’) Guide To Winning: Colorado BHA Examples (Browns Canyon & Camp Hale).”[4] Also see: Randy Newberg and TRCP. “Scrubbing out public land transfer myths.” TRCP: 6/11/16.
David Lien is a former Air Force officer, author, and co-chairman of the Colorado Backcountry Hunters & Anglers. During 2019 he was the recipient of BHA’s Mike Beagle-Chairman’s Award “for outstanding effort on behalf of Backcountry Hunters & Anglers.”[5]
Additional Information/Resources
-Colorado Parks and Wildlife. “Colorado’s 2021 Guide for Planning Trails with Wildlife in Mind.” Appendix A includes standard protocols for how and where the trails are developed (i.e., Avoid, Minimize, Mitigate).
-David A. Lien. “6x6 Karma: The Bear Facts.” Backcountry Hunters & Anglers: 11/12/24.
-David A. Lien. “Project 2025 puts public lands in peril.” Colorado Newsline: 8/2/24.
-David A. Lien. “Elk Hunting: A State of Mind (& Body).” Backcountry Hunters & Anglers: 11/21/23.
-David A. Lien. “Colorado Backcountry Hunters & Anglers Increase Reward For Illegal Trail Construction (Help Stop Trail Building ‘Free-For-All’).” Backcountry Hunters & Anglers: 4/10/23.
-Theodore Roosevelt Conservation Partnership (TRCP). “Outdoor Recreation and Elk: A Colorado Case Study. Where do elk habitat and recreational trails overlap in Colorado, and why does it matter?” TRCP Case Study: 2022.
-Liz Rose. “40% of Most Important Colorado Elk Habitat Is Affected by Trail Use.” Theodore Roosevelt Conservation Partnership: 9/27/22.
-Brien Webster and Kriss Hess. “CO BHA Publishes Memo on Illegal Trails.” Backcountry Hunters & Anglers: 8/24/22.
-David A. Lien. “Reward For Illegal Trail Construction Offered By Colorado Backcountry Hunters & Anglers.” Backcountry Hunters & Anglers: 1/31/22.
-Brittany Parker. “Trails Based Recreation And Its Impacts On Wildlife.” Backcountry Hunters & Anglers: 1/31/22.
-David A. Lien. “More trails a slippery slope to less hunting.” Grand Junction (Colo.) Daily Sentinel: 12/9/21.
-David A. Lien. “Trails vs. Elk: ‘They’re Just Dying Off.’” Backcountry Hunters & Anglers: 12/3/21.
-Brien Webster. “Colorado BHA Report: Impacts of Off-Road Recreation on Public Lands Habitat.” Backcountry Hunters & Anglers: 5/21/18.
-Sylvia Kantor. “Seeking Ground Less Traveled: Elk Responses to Recreation.” Science Findings #219 (U.S. Department of Agriculture-Forest Service Pacific Northwest Research Station): September 2019. https://www.fs.fed.us/pnw/sciencef/scifi219.pdf
-The importance of roadless areas to Colorado’s fish, wildlife, hunting and angling is detailed in this Trout Unlimited report (authored by David Petersen and Keith Curley): “Where The Wild Lands Are: Colorado.”
Founded by Mike Beagle, a former U.S. Army field artillery officer, and formed around an Oregon campfire, in 2004, Backcountry Hunters & Anglers is the voice for our nation’s wild public lands, waters and wildlife. With members spread out across all 50 states and 13 Canadian provinces and territories—including chapters in 48 states, two Canadian provinces and one territory, and Washington, D.C.—BHA brings an authentic, informed, boots-on-the-ground voice to the conservation of public lands. The Colorado BHA chapter was founded by David Petersen (a former U.S. Marine Corps helicopter pilot) in 2005 (the first official BHA chapter)
[1] David A. Lien. “Project 2025 puts public lands in peril: Plan for a second Trump administration threatens wildlife habitat in Colorado.” Colorado Newsline: 8/2/24.
[2] David A. Lien. “Project 2025 puts public lands in peril: Plan for a second Trump administration threatens wildlife habitat in Colorado.” Colorado Newsline: 8/2/24.
[3] David A. Lien. “Colorado Backcountry Hunters & Anglers Increase Reward For Illegal Trail Construction (Help Stop Trail Building ‘Free-For-All’).” Backcountry Hunters & Anglers: 4/10/23.
[4] David A. Lien. “A Hunter-Angler (Hell-Raisin’ & Habitat Savin’) Guide To Winning: Colorado BHA Examples (Browns Canyon & Camp Hale).” Backcountry Hunters & Anglers: 10/23/23.
About David Lien