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Trail closures give wildlife a critical winter refuge

Mule deer struggle the most with rising pressure from recreation
A sign on closed gates notifies Sale Barn Trail users that the area is closed to provide winter range for wildlife. Mule deer and elk are particularly vulnerable to the effects of recreation in winter. (Jerry McBride/Durango Herald)

A familiar sight will greet Durango residents who recreate this winter: trail closures.

Twin Buttes, Animas City Mountain, Grandview Ridge and Bodo State Wildlife Area are just a few of the open spaces that close portions of their trails starting Dec. 1.

Trail closures are not unusual in Southwest Colorado, where elk and mule deer move to lower elevations to overwinter. They’re billed as a way to protect wildlife and limit trail damage during snowy months.

But many recreationists may not understand why or how public agencies make these decisions.

Trail closures are the result of a growing body of research that shows recreation can impact wildlife as much as extractive industries, threatening the survival of populations. Wildlife and public land managers try to balance their responsibilities to recreation and wildlife, but often find themselves defending animals increasingly under pressure from human activities in Southwest Colorado.

“The quagmire we have at the Bureau of Land Management is that we are dealing with big game winter range. The majority of the places where we develop houses (and) roads are also part of that winter range,” said Neil Perry, a wildlife biologist with the BLM in Southwest Colorado. “We’ve displaced the historic herds in these places.”

“All that adds up to our BLM lands and some state lands being the last refuge for big game and therein lies the conflict and the challenge with increasing recreation and trail use,” he said.

Mule deer and elk are the two species that wildlife and public land managers usually consider when closing a trail for the season.

With a smaller population and less frequent sightings, elk might seem like the species most affected by recreation, but it is mule deer, which evolved in Colorado over thousands of years, that struggle with habitat loss and a growing human presence.

“Mule deer tend to be more sensitive to new trail development in large part again because their migrations are learned and taught to them by their mothers in their first year of life,” Perry said. “Elk tend to herd up and move as resources are needed.”

Eliot Wright and his dog, Frankie, make their way down Animas City Mountain Trail on Thursday. The Animas City Mountain Trail system is one of the many recreation areas around Durango with seasonal trail closures for wildlife. (Jerry McBride/Durango Herald)

Research over the last three decades has shown that recreation disrupts and harms both mule deer and elk.

A study by researchers at Colorado State University in 2000 found that human disturbance decreased the reproductive success of elk by more than 20%.

Hikers and mountain bikers on trails displace mule deer by more than 400 feet, according to a 2003 paper published in Ecological Applications. Off trail, they force deer to move an additional 200 feet.

A 2018 study in Forest Ecology and Management found that elk maintain roughly 0.3 miles of separation from hikers and horseback riders, 0.4 miles from mountain bikers and 0.55 miles from ATVs.

These distances might not seem like much, but they effectively decrease wildlife habitat.

Winter magnifies the impacts of recreation and lost habitat. Elk and deer are bound by snow at higher elevations and human activity at lower elevations.

Wildlife and land manager use trail closures to limit the harmful effects of recreation on elk and mule deer. A study by researchers at Colorado State University in 2000 found that human disturbance decreased the reproductive success of elk by more than 20%. (The Journal file)

“Winter range is a resource that is slowly being lost as the human footprint expands through development and increased recreation,” said John Livingston, a spokesman for Colorado Parks and Wildlife in Southwest Colorado.

The quality of forage for elk and deer also decreases during winter, leaving animals particularly vulnerable.

“It’s like if you go to the grocery store and suddenly for months all of the food is less nutritious,” Livingston said. “Big game animals are essentially living off their fat reserves until their forage regains its quality. Each time they move unnecessarily, it is wasted energy.”

“When there’s snow on the ground, the deer are struggling,” Perry said. “Physically, they’re in a state of starvation during the winter and the females are all pregnant. A dog that chases them for 100 yards might not seem like a lot, but those are calories that they weren’t designed to expend multiple times every day.”

“Every ounce of fat that they lose over the course of the winter decreases their probability of a successful migration in spring,” he said.

Seasonal closures have become a tool for public agencies to curb the severe effects of recreation during winter.

CPW, the BLM and the U.S. Forest Service all close areas of public land from Dec. 1 until April.

Closure dates are determined by telemetry and GPS data that wildlife managers have collected about mule deer migrations.

“Deer and elk move onto winter range either based on time of year or snow conditions on summer and transitional range,” said Steve McClung, CPW assistant area wildlife manager. “People commonly wonder why there are winter (trail) closures if there is no snow, but when you look up into the mountains there is snow that these animals are coming down to get away from.”

Closures last through the middle of April because animals cannot return to their summer grazing areas until the snow melts with spring runoff, Livingston said.

Wildlife officials say Perins Peak is a crucial winter range and an important migration corridor for elk and deer. The city of Durango and Colorado Parks and Wildlife close the upper loops of Twin Buttes to prevent people from disturbing wildlife that overwinter there. (Courtesy of Cole Davis)

While popular trails closing can frustrate hikers and bikers, CPW, the BLM and the U.S. Forest search for ways to allow recreation while limiting the effects on wildlife.

In some cases, the decision may come down to something as simple as tree density.

Managers may choose to leave a trail system surrounded by thick forests that shield animals, Perry said.

“It’s a balance,” Perry said. “If an area doesn’t have high density big game use or has poor quality habitat, we might leave that area open and then favor protective measures (in) areas where it can be a lot more effective.”

CPW released a planning guide for new trail developments in June 2021 outlining strategies land managers could use to protect wildlife while expanding recreation.

The report highlighted constructing of new trails in less sensitive wildlife habitat and limiting trail densities as two potential strategies.

“One nice thing about trails is that they can help us route use away from critical resources whether it’s cultural or some finite habitat resource,” Perry said. “We can use trails to inhibit user access.”

But according to Perry, few of these solutions can replace seasonal trail closures.

“Both as a wildlife biologist and with my mountain bike helmet on, I think the benefits tend to outweigh the potential negative impacts,” he said.

“Sometimes simple is the best,” he said.

CPW and BLM officers patrol trail closures every year to ensure that hikers and bikers aren’t visiting prohibited areas.

CPW issues on average a dozen citations every year, Livingston said. After additional charges, the ticket comes out to $139.50.

According to Perry, who monitors trails with wildlife cameras, 98% to 99% of people respect trail closures.

“I don’t think it’s critical to the resource that we have 100% compliance,” he said.

“It’s not that animals aren’t going to be tolerant to some disturbance, it’s that we are greatly reducing the measure of that disturbance,” he said.

Still, growing recreation will continue to put pressure on wildlife, making the work of land and wildlife agencies even more difficult.

“You hear a lot of the news about the impacts to mule deer and other wildlife as we increase all these uses across the landscape. Oil and gas is one that gets a lot of attention as a really negative development, but those wells have a limited lifespan,” Perry said. “… In 200 years, most of our oil and gas developments in Colorado will probably be gone entirely, but in 200 years, I guarantee you we’re going to have a lot more singletrack.”


Trail closures

These trails are closed to public use annually from Dec. 1 to April 15, with possible extension to April 30:

Grandview Ridge.

Big Canyon and Sale Barn trailheads (access located east of U.S. Highway 160).

South Rim Trail, portions of Sidewinder and Cowboy trails on BLM land accessed from Carbon Junction Trail or Crites Connect.

Grandview BLM trails (access from Three Springs).

Animas City Mountain – BLM lands above the lower loops (about 1.5 miles above the 32nd Street trailhead).

Twin Buttes Area – all upper trails as marked.

Bodo State Wildlife Area – Exception: Smelter Mountain Trail is open from 10 a.m. to 2 p.m.; dogs are prohibited. Small game hunting is allowed in the area south of La Plata County Road 210.

The Perins Peak area east of County Road, 208 and west of Hogsback will be closed through July 31. Perins Peak is open only to pedestrian traffic for the remainder of the year, and the northernmost trails on Animas City will also be closed through July 31 to protect nesting peregrine falcons.

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