There are pockets of Colorado aspen groves that bear so many scribbles and drawings that the trunks look like graffiti-covered bathroom stalls. While some are made by egotists, some marks have been left by sheepherders who have turned the tree bark into historical diaries stretching back decades. Groups of migrant workers have been traveling to Colorado from Mexico and Peru for nearly a century to find work in the U.S. during the summer months, and Dr. Alison Krögel, professor of Andean and Quechua Studies at University of Denver, tunneled into the backstories behind the cryptic messages these visitors left on our trees, from 1925 to present.

Her research offers a comprehensive study into the aspen carvings (called “arborglyphs”) of northwest Colorado that herders left behind, and the resulting Aspen Archives exhibit is now displayed at the Davis Gallery, in DU’s Shwayder Art Building. The bilingual presentation of photos and interpretive panels busts a few myths and misconceptions about these nomads—including their reputation as soft-porn illustrators.

Erotica is certainly a dominant theme, carved by sheepmen who created the companions they probably wished they had during their solitary, summer-long exile in the forest. Nude women with voluptuous breasts and buttocks remain on the trees, with some carvings dating from the 1930s.

But herders also left a host of other records that speak for an otherwise voiceless population. Spending three to four solitary months without human contact (herders work solo or in pairs) has never been a coveted job, and in northwest Colorado where Krögel focused her research, most herders were immigrants from Mexico and later, Peru. They had no families or connections to urban Colorado, but left their names, preoccupations, frustrations, and cravings on the aspens.

“Topics range from recent bear sightings; complaints of too much rain or a lazy co-worker; celebrations of the popular Peruvian soft drink Inca Cola or the Peruvian cumbia band Juaneco y su Combo; patriotic messages aimed at buoying fellow Peruvians during the years of Shining Path conflict; and most commonly, exact month-day-year chronicles of a specific herder’s passage through the forest,” explains Krögel, who was surprised by the diversity of the carvings’ themes.

A picture of an aspen tree carved with letters and numbers.
An arborglyph carved into aspen trees in Routt Forest. Photo by Paul Thomas Raugust

She also uncovered details about the carvers themselves. For two years, Krögel mined photo collections and logged interviews with current and retired herders, wool processors, and forest rangers. She also combed archives from museums in Colorado and New Mexico to document sheepherder histories and patterns.

One discovery corrected the prevailing, Euro-centric assumption that Colorado’s sheep-sitters hailed from northwestern Spain. Basques did herd sheep (and carve aspens) in many parts of Nevada, California, Utah, Idaho, and in some regions of Colorado as well. Yet in northwest Colorado, the sheep-sitters initially came primarily from Greece and later from northern New Mexico, Mexico, and, beginning in the early 1980s, Peru. They still do—and they still struggle to connect with this state’s inhabitants. Language barriers add to the herders’ geographic isolation, so that even when herders encounter occasional hikers and mountain bikers in the forest, few Coloradans can speak the Spanish or Quechua languages that they know. “Still, most herders I’ve spoken with have told me that they enjoy meeting outdoor recreationalists during the summer months, even if conversations are limited to basic pleasantries,” Krögel says.

Seeking human connection—or the most basic affirmation that they exist—these immigrants leave their records on the trees, and the Aspen Archives exhibit broadcasts and interprets those messages.

“I think that viewers often consider aspen carvings as meaningless graffiti, or as a harmful act that damages the tree,” Krögel says. The exhibit includes an interview with plant biologist Dr. Julie Morris that addresses the negative effects of carving on trees. But it also explores how, over the past century, most herders caring for sheep in Colorado’s high-country forests have labored far from their homelands, often in prolonged solitude. Krögel explains: “It seems clear that in this context, inscribing their presence upon the new landscape has become an important and frequent practice for generations of herders.”

The Aspen Archives exhibit remains at the Davis Gallery through October 20. Afterward, the exhibit will travel to the Tread of Pioneers Museum in Steamboat Springs, and then on to Huancayo, Peru—the home region of most of the sheepherders that work in Colorado.