Digging rodents are a constant battle for property owners in Teller County, but following a particularly mild winter, their populations have ballooned to untenable levels. Seeking strategies for dealing with these dastardly diggers, the Courier spoke with Tyler Krumrey of Peak Wildlife Services and Darian Founds, the Teller County CSU Extension director.

Colorado is home to several species of burrowing rodents that play important roles in the Rocky Mountain ecosystem, but they can also cause significant damage to foundations, landscaping, irrigation systems and agricultural property while also creating hazards for humans, livestock and other wildlife.

“Correctly identifying the animal is the first step toward effective control, as different species leave distinct signs and require different management strategies,” Krumrey said. “Among the most common digging rodents in Teller County are voles — there aren’t moles in Teller — chipmunks, pocket gophers, ground squirrels and prairie dogs.”

Identifying the Culprit

Voles (also known as meadow mice) are often the first diggers to emerge in the spring. During mud season or prolonged periods of rain, vole tunnels create surface veins that rise about an inch off the ground. When the ground is dry, networks of surface runways and patches of dead grass indicate their presence.

Voles DO NOT plug their surface holes, so open holes about two fingers in diameter and interconnected by trails are a good indication the culprit is a vole.

“They are predominantly herbivores and eat plants both above and below the ground,” said Founds. “Don’t let their small size fool you. They can girdle and kill trees.”

Similarly sized holes that ARE plugged are a sign of chipmunks. Though chipmunks are surface feeders and arguably the cutest of the dastardly diggers, when their populations reach infestation levels, their burrowing can be astonishingly destructive, destabilizing mature trees, retaining walls and concrete features like sidewalks, driveways and stairs.

Pocket gophers make fan-shaped or crescent-shaped mounds of loose soil with a plugged entrance offset to one side. The entrance hole may be buried near the mound, but it is about the diameter of a racquetball. Tough pocket gophers are solitary animals that spend most of their lives underground. They excavate extensive tunnel systems while feeding on roots, bulbs and other underground plant material.

In addition to creating unsightly mounds, gophers kill landscaping and young trees by consuming roots and their tunnels may destabilize mature trees, damage underground irrigation lines or create hazardously uneven ground.

Open surface holes with no surface mound or a hard-packed volcano-shaped mound will indicate either a ground squirrel or prairie dog. Though they look and behave quite similarly, the biggest distinction is their size. Ground squirrels are roughly the same size as a tree squirrel, and their holes are 2-4 inches in diameter with no significant mound. Ground squirrels tend to be solitary.

Prairie dogs are much larger, about the size of a bunny. The burrow entrance is 4-6 inches in diameter, and a volcano-shaped lookout mound is a distinguishing feature. Prairie dogs live in extensive colonies. Because of their size and grouping behavior, prairie dog colonies litter grassy areas with trip hazards that can harm humans, livestock, pets and wildlife.

Mitigating the Problem:

Some ways to reduce a pest’s desire to be on your property are to keep grass cut short, get rid of attractants like bird feeders, encourage predators by installing things like owl boxes and installing galvanized hardware cloth.

“I get calls just about every day from people wanting to resolve a digging rodent issue,” said Founds. “The most common question is how to deter them, and though there are a lot of methods out there that may annoy a digging rodent enough to get them to move — things like sonic devices, thiram, garlic, capsaicin, kitty litter, dog poop — the pests rarely move very far, and the problem persists.”

When deterrents fail, the next call is about relocating them.

“This is only realistic when there’s a very small number of animals, and even then, it’s not a great option,” Krumrey said. “Any movement of wildlife is regulated by CPW and requires landowner consent. We’ll do it, if that’s what a client wants, but for a home remedy, between the cost traps and time it involves, it can be more work than it’s worth.”

Founds added, “Most of the time, relocating an animal is just another way of killing them. They don’t have food and shelter resources. It may seem like a humane choice, but that’s not the reality. Plus, it requires handling rodents which are notorious disease carriers. But still, a lot of people are reluctant to jump to the lethal options.”

Poisons and gases are a popular first line of lethal mitigation.

“Done right, these are effective options, but again, the do-it-yourself method is going to come with a learning curve,” Krumrey said. “Poisoning requires caution and some understanding of the target animal’s feeding behavior, and off-the-shelf gassers won’t work if their placement isn’t just right and the tunnels aren’t sealed.”

“It is very important for homeowners to read and follow labeling instructions if they are using poison,” Founds said. “Zinc phosphide is the most common home-use rodenticide, but it is dangerous to people, pets and wildlife. You need to be very careful when using it, and even then, you run the risk of accidentally poisoning the predators who kill hundreds of these pests.”

If you’re willing to get more hands-on with the elimination process, lethal traps are very effective tools. Small diggers, voles and chipmunks, can be effectively caught with simple snap traps and rat traps. If using an uncovered version of these traps, cutting small holes in a cardboard box at two ends and placing the traps inside will keep birds from accidentally triggering the traps and will deter predators from running away with your trap. Place the traps along their pathways, and if they’re active, your odds of successful trapping are good.

Underground traps are effective tools for population control of gophers, ground squirrels and prairie dogs. Wire traps like those made by Victor cost about $8, they take some digging and practice to set, but once mastered, they work very well and the price makes multiples feasible.

More sophisticated traps like the Gopher Hawk (which will also work on ground squirrels and prairie dogs) may be easier to use, but at $30-$40 each, the price can be unrealistic for an infestation. For those seeking a strictly passive method of extermination, consider that lethal traps do not always finish the job and occasionally an act of compassion requires a swift blow to the head.

If the hands-on approach is not in the cards, services like those offered by Peak Wildlife Services can be a godsend. However, maintaining a pest-free perimeter is a labor-intensive process which — if done by a professional — comes at a matching cost. Establishing and maintaining that perimeter can cost several hundred dollars per visit, and several thousand dollars per year.

Krumrey notes that prairie dogs are a protected keystone species.

“Though a homeowner can kill prairie dogs that are causing property damage, pest control companies are strictly regulated in their ability to help homeowners with a prairie dog problem,” he said. “Some don’t deal with them at all because of the red tape.”

Though complete elimination of those dastardly diggers is unrealistic, there are ways to keep their populations in check. Often the multifaceted approach is the most effective, and it combines deterrents, well-placed poisons and lethal methods (be it traps or a pellet gun). A smart strategy is to establish a zero-tolerance zone and not try to control areas too large to manage without devoting excessive amounts of time and money to the problem.