Esker Diggers
- IPWA
- 2 days ago
- 3 min read
By Rob Pudim and Kelly Prendergast
Have you ever seen ridges like these in the Indian Peaks or James Peak Wilderness? Ever wonder what makes them and why?
What are "eskers" and how are they made?
Eskers are long, narrow dirt ridges that branch and intertwine like roots and appear in mountain meadows as winter snows melt away. At first glance they look like tunnels that some little creature must run through, but upon further inspection are solid inside. So what makes these unusual structures?
Meet the northern pocket gopher, Thomomys talpoides, a small mammal, six to 10 inches long with brown fur, a short tail, small ears and small eyes.
Our longtime IPWA Volunteer, Rob Pudim, affectionately refers to pocket gophers as an LBJ (little brown job) as it is one of several small rodents that inhabit the Indian Peaks and that live under the snow in winter.
Pocket gophers do not hibernate; instead they spend the winter season doing the dirty work, literally, of digging and burrowing. Burrow systems are elaborate and often bi-level, and can be up to 400 to 500 feet long. Pocket gophers are also very territorial about their burrows, there is only one gopher per burrow.
A shallow level, approximately one foot below the surface, is used to store feces. A deeper layer, two feet or more below the surface, is used for the nest and food storage. A third layer is constructed in winter, at ground level but beneath the snow. Pocket gophers fill their snow tunnels with soil excavated in winter, and these tubes of soil (eskers), remain behind when the snow melts, leaving ubiquitous evidence of gophers in mountain meadows.
Note their large yellowish-orange incisors, two upper and two lower, that are always visible and always growing. When their incisors are first developed, they pierce the upper and lower lips, so their lips close behind their incisors, allowing gophers to carry rocks with their incisors while keeping their lips sealed.
They are stocky animals, with short, powerful limbs and large front paws and claws used for digging. Their cheek pouches open externally, to carry food and nesting materials.
The pocket gopher family of rodents, is showing its teeth and claws. Like all rodents, its self-sharpening teeth continue to grow throughout its life.
Range: New Mexico to Manitoba and from northern California to eastern North Dakota.
Habitat: Sagebrush, meadows embedded in forests and alpine tundra.
With immense geographic range, there are more than 50 subspecies of northern pocket gophers, six of them in Colorado.
What they eat: grass, roots, seeds, and buds
Predators: birds of prey (owls, hawks, herons), mammals (coyotes, foxes, bobcats, weasels, badgers, domestic dogs/cats), and snakes
Credits:
Excerpts taken from a July 19, 2010 article written by Jeff Mitton (mitton@colorado.edu), Professor Emeritis, Department of Ecology and Evolutionary Biology at the University of Colorado. The article "Secret Pocket Gophers" originally appeared in the Boulder Camera.
Excerpts taken from January 15th 2025 article from the Jackson Hole Buckrail written by River Stingray, a news reporter who holds a Master's degree in environmental archaeology from the University of Cambridge
Naturalist column exploring high country flora, fauna and geography
IPWA volunteers are often asked by visitors not just about the trails, but about what they are seeing in the Indian Peaks and James Peak Wilderness Areas. This column will cover some of the plants, animals and geographic features that hikers, anglers and backpackers may come across in these areas.
About Rob Pudim
A long time Boulder resident, Rob describes himself as “a coal-miner's son from Pennsylvania, a "fallen" scientist (Chemistry, Rutgers University and Microbiology, Tulane University) an editorial cartoonist, an amateur lepidopterist, a Native Plant Master, and a long-time birder”. His affiliation with IPWA goes back to its founding in the 1980s.
About Kelly Prendergast
Longtime volunteer and former board chair: "My grandparents, who loved birds and plants, were a huge influence in my life growing up in the Hudson Valley and Catskill mountains of New York State. My siblings and I were encouraged to spend many hours exploring the nearby woods which fostered a lifelong curiosity and desire to learn more about the natural world. I'm continuously surprised by the abundance of things to discover and love hearing about and sharing new discoveries with others."
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