Don’t fence me in: Wild animals face increasing habitat fragmentation, but some land managers are trying to help


Images taken with a wildlife camera at Mesa Verde National Park show an elk successfully navigating special fencing. Courtesy of Paul Morey/Mesa Verde National Park

Good fences make good neighbors. — Robert Frost

One of the things most people relish about living in the Four Corners region is being surrounded by wildlife habitat.

We might come face to face with a deer (in town!), marvel as a herd of elk moves across a mountain meadow, or just find pleasure spying a kingfisher or bald eagle.

But as Colorado’s rural population grows and previously undeveloped areas become suburbs, industrial parks, farms, or drilling sites, wildlife habitat decreases, leading to conflicts between people and free-roaming animals. And despite Frost’s statement, fences can actually exacerbate those conflicts.

Colorado has been a “fenceout” state since the 1880s, meaning property owners who do not want livestock on their property must fence them out, since livestock owners do not have an obligation to keep their animals in.

Once any landowner builds a ‘lawful’ fence – defined in Colorado statutes as a “well-constructed three barbed wire fence with substantial posts set at a distance of approximately twenty feet apart” – then that landowner may “recover damages for trespass and injury to grass, garden or vegetable products, or other crops of such person from the owner of any livestock which break through such fence.”

But, “If no fence exists, animal owners are not responsible for nonwillful trespass,” according to a ruling in a 1940 case known as Bolten v. Gates.

But fences can cause problems for wild animals, interrupting migration routes and bisecting territory. While some animals can navigate the barriers either by jumping over them or crawling under, others get caught and suffer horribly.

That sad occurrence happens more often than you might think.

In a study in 2005 and 2006, Utah State University researchers J.J. Harrington and M.R. Conover walked, drove and flew over 600 miles of fence in two seasons, tallying animals they found trapped. They found an average of one tangled animal for every 2.5 miles of fence per year. Most were snared in the top two wires as described by Harper. Young animals were eight times more likely to get caught than adults, with deaths peaking in August, when fawns were weaned.

“It’s a pretty routine call for us, that an animal is caught in a fence,” said Dave Harper, wildlife program manager with Colorado Parks and Wildlife’s Durango office.

Calls come from both rural and urban locations. Harper said there are some fences that are “notorious animal catchers” in Durango, tall fences with spikes.

In addition to becoming entangled in fences, many ungulates were found dead next to a fence, trapped and stranded.

“The mothers can jump those fences with ease, but the little ones get trapped,” Harper said.

The Utah study found an average of one animal carcass lying next to a fence per every 1.2 miles per year. Ninety percent were fawns curled up next to the barrier.

Fences of woven wire topped by a single strand of barbed wire caused the most problems, according to the Utah researchers.

A “bad” fence does not adhere to regulations. It can have loose or broken wires, wires placed too close together, or posts too close. It will be too high for animals to jump or too low for them to crawl under. Barbed wire, stakes and metal posts can impale or cut a jumping animal.

Slow death

Paul Morey, wildlife manager at Mesa Verde National Park, told the Free Press a good range rider can alleviate some of the problems associated with bad fences. “You can drive around Montezuma County and see which fences aren’t maintained,” he said.

Range riders can tighten the wires to ensure livestock doesn’t get out, and can remove trapped animals.

CPW can respond to help landowners remove animals from fences safely. Harper recommends that people don’t try to do it themselves unless they know what to do.

“You can cause more damage if you do it wrong. If the animal is stressed out and trying to escape, cover their heads and eyes,” he said. “We’ll walk up and throw a jacket over them and then they calm down. Then we can make a determination once they’re out.”

He finds a lot of animals with a broken legs or a broken pelvis, or dislocated hips. He will assess what kind of injury the animal has sustained and whether or not it can be saved or the meat can be salvaged. This may depend on how long it’s been trapped, but usually the animals are so stressed that the meat is unfit for consumption.

Morey explained that deer jump with “their back legs facing forward, so the back legs slip between two wire strands and when they go over, the top and second wires are wrapped around their legs.” The result is often a slow, miserable death.

Friendly fencing

One solution is wildlife-friendly fencing, which comes in different designs and sizes, all intended to allow animals to either jump over or crawl under.

There are some key features of wildlife friendly fencing: it should be between 40 and 42 inches tall, with a distance of 12 inches between the top two wires. The bottom wire or rail should be at least 16 inches and preferably 18 above ground. Both the top and bottom wires should be smooth, not barbed.

Don’t use vertical stays on the wires, and make sure the posts are placed at 16.5-foot intervals. Gates, drop-down sections, or other lower, wildlife-friendly sections should be placed where animals are known to concentrate and cross.

Other ways to make fences more wildlife-friendly include making them more visible. Some landowners tie white or red flagging on the top wire. Another strategy includes using vinyl covered wire for the top strand, or coloring it. These techniques help game fowl such as grouse, or larger birds and raptors like swans, hawks, or eagles, see the fence. Morey was instrumental in getting wildlife-friendly fencing put in at Mesa Verde.“It’s more expensive but it’s proven to be highly effective for the park,” he said.

They installed a high-tensile fixed, not woven, fence, which is so highly tensile that the 12-gauge wire stretches. Morey said he saw someone drive a vehicle into this fence, which stretched 100 feet, then returned to its normal position without any damage.

About four miles of such fencing has been put up in the park so far, and they plan to install more over the next ten years.“The first fence we put up with this design was seven years ago,” Morey said.

“It’s half a mile long in an area with a high density of elk and horses, and lot of pressure from the outside. To date there are no breaks and we have done no maintenance.”

Morey has only seen one animal caught in a fence at the park since 2010. Elk are such large animals that they can ruin an entire section of fence if a herd is startled and crashes through. Wildlife-friendly fencing therefore prevents not only gruesome death, but also property damage.

Harper said animals can make it over fences if they’re made the right way and the animal is given a chance. “We need to back off and give the animals time to negotiate the fence,” he said. “By themselves, they have no problem, but if you get them hurried and running they will get into trouble. ” Morey agreed, saying that in places where the park has installed wildlife friendly fencing biologists have set up wildlife cameras and seen elk and deer walk along the fence to a lower spot, then jump over (see photos).“These animals that see the fence, they live in these areas, they know where the fences are, unless they’re being chased,” said Morey.

Harper said, “It’s when somebody’s pushing them, harassing them, getting too close in order to take photos, or when the deer get too close to snow machines, that they get caught. When people are driving up a road, they’ll startle the animals – and then they blow through the fencing.”

CPW urges people not to get too close to wild animals. Keep dogs from chasing wildlife, and don’t push or harass them by trying to get closer in your vehicle, snow machine or skis. Use your zoom to take a photo!

Keeping livestock out

Morey was trained as a biologist – he is leading a sold-out tour and giving a lecture on raptors for the Ute Mountain/ Mesa Verde Birding Festival. However, much of his job has to do with maintaining fences. In 1901,when Mesa Verde was created, there were no fenced boundaries and cattle were allowed to graze in the park. Now approximately 50 to 70 percent of the park is fenced, according to Morey.

The park’s concern is keeping livestock out and keeping wildlife habitat intact. There are about 80 horses and 12 cattle inside park boundaries. Besides the fact that cows and horses are not native, “the livestock in the park are having an impact on the natural and cultural resources,” said Morey. The park is trying to figure out what to do to get them out and keep them out.

The park is seeking public commentary on a livestock-removal project. This goes hand in hand with installing the new fencing, so livestock will stay out but wildlife can move back and forth. Interested citizens can see the plan at the visitor center or online and are encouraged to submit comments. (Link is in the “Resources” box at left.)

Wildlife-friendly fencing can be expensive. Morey estimated the installation of the high-tensile fence at Mesa Verde cost about $100,000 per mile. But this initial outlay is offset by the reduction in fence maintenance and animal retrieval, so he believes it is worth the expenditure.

Highway barriers

Right-of-way fencing and/or livestock fencing is in place along most highways, potentially creating barriers to wildlife migration.

Jeff Peterson, wildlife program manager with Colorado Department of Transportation, says CDOT determines whether to install wildlife-friendly fencing after consulting with CPW biologists about population numbers and migration routes of animals killed on highways.

“CDOT will not install wildlife fencing without providing a wildlife crossing every half-mile to a mile to allow for safe movement over or under the highway and installing escape ramps so if an animal does end up trapped on the highway, they have a way off,” Peterson said.

“We are very aware of the need to maintain daily and seasonal movements of wildlife and the importance of genetic flow on either side of the road. We would rather not install a fence than to prevent those things from occurring.”

Fencing and other wildlife-mitigation features including motion sensors, wildlife underpasses and overpasses are usually paid for out of the CDOT and federal highways budgets. CDOT’s most recent wildlife-friendly fence installation was on State Highway 9, south of Kremmling. Ten miles of fence were installed, along with the first wildlife overpasses in Colorado.

Peterson said this was an unusual situation: “A private landowner, very rich, gave CDOT money to redesign the road and put in wildlife mitigation. After we accomplished that, the landowner, Kremmling, Grand County, and private citizens raised money to add to CDOT and the federal highways budget to complete construction. Once it was completed we saw a 94 percent drop in animals being struck on the highway.”

Private landowners have several options if they want to build wildlife-friendly fences. CPW has an excellent brochure, Fencing with Wildlife in Mind, as does the state of Montana (links below). Most local fencing companies offer wildlife-friendly fencing options. The Habitat Partnership Program, funded by CPW through state big-game license revenues, is intended to reduce impacts caused to agriculture by elk, deer, pronghorn and moose. Landowners can apply for help with fencing repair and new construction, including wildlife-friendly fencing. They can also receive support for game damage to haystacks and fences; habitat manipulation such as weed-cutting and spraying; water development (usually pond construction or clearing); research and monitoring; as well as conservation easements and archaeological assessments.

Harper is a member of the Montelores HPP committee, which meets monthly to discuss local projects. Landowners wishing to build any kind of fence might want to recall another part of Frost’s Mending Wall: “Before I built a wall I’d ask to know, what I was walling in or walling out, and to whom I was like to give offense.”

Wild animals may not have the opportunity to express offense at being trapped by a fence. But their agonizing deaths surely cause humans some distress. The least we can do is be accountable stewards of the land who build fences that will sustain, not maim, wildlife and livestock.

“It’s usually more of a people problem than an animal problem,” said Harper.

Morey agreed. “You have to manage people to manage the wildlife.”

The Free Press thanks Deb Jensen of Mancos, Colo., for this story idea.

If you find an ensnared animal

To report injured wildlife or a problem call the CPW regional office, (970) 247-0855 during office hours, and after hours or on holidays call the Colorado State Patrol at 303-239- 4500. Do not try to remove an injured, living animal yourself.


Montana Fish and Wildlife brochure for wildlife-friendly fencing for landowners:

Colorado Parks and Wildlife: Living with Wildlife

CDOT wildlife program:

Mesa Verde Livestock Removal Environmental Assessment (public comments due May 13):

From May 2018.