Some carvings are rousing political slogans. Others depict sexual exploits. And like modern graffiti, a great many merely note for posterity that Joe, Jose, or, most likely, Joxe, "was here."

As anthropologists have spent decades combing the red rock landscape of the Southwest for petroglyphs — the prehistoric scrawlings of American Indians — researchers in the Northwest are just beginning to discover a widening trove of arborglyphs — 19th and 20th century tree carvings by Basque sheepherders.

Scholars say the drawings provide a blueprint for Basque immigration patterns across the western United States and unlatch a window into the psyche of the solitary sheepherder.

"These give us insight into a group that largely did not leave behind a written word," said John Bieter, the executive director of the Cenarrusa Center for Basque Studies at Boise State University.

Basques hail from a semiautonomous region joining the Pyrenees of northern Spain and a slice of coastal territory in southern France. Basques are believed to be some of the oldest inhabitants of Europe.

On the heels of the California Gold Rush in 1850s, Basques who had already emigrated to South America followed the ore's elusive path across the West.

Basques quickly branched out to sheepherding, a common 19th century parallel to many of today's migrant labor options, Bieter said. Soon after, tree etchings began appearing in the alpine hollows of California, then Nevada, Idaho, Wyoming and other western states.

The legacies of men like Julio Ramon are etched into the bark. In an undated inscription from an aspen grove in the Boise National Forest, Ramon trumpets a rallying cry into the empty wilderness: "Gora ETA."

The phrase — roughly "Long Live ETA" — was a political maxim of the armed Basque separatist group known by the initials. It is most common in tree engravings among a second wave of sheepherders who likely lived in Spain under the nationalist dictator Francisco Franco, Bieter said.

"He could carve it into a tree in Idaho, but if he said it Spain, he'd be imprisoned," Bieter said.

Susie Osgood, a Forest Service archaeologist, said she has identified about 300 trees with Basque carvings. They are considered a cultural resource, like artifacts from Chinese mining camps and American Indian tent sites.

"It's a realistic window into what you think and do out here when you're all alone," she said. "Now, the herders have headsets and things, but in the 19th century, you were your own entertainment."

Over three days in mid-July, Bieter and students from his summer seminar catalogued dozens of arborglyphs for a database maintained by the Boise National Forest.

Basque sheepherders livened the hours of solitude by drawing and a great many tree carvings are crude sketches or a simple name and date.

"If you think about it, a lot of people write on toilet walls, sitting around with nothing better to do," student Nick Allex, 21, said while measuring and inscribing a patch of arborglyphs. "It's kind of the same concept."

In Idaho, Bieter has noticed explicit pictures and sexual themes as a common thread.

In an Idaho Aspen stand, a herder praises the mild weather, while also noting in graphic prose that no one short of a highly skilled prostitute could make him cheerier.

Some carvings also reveal a glimpse into the dormant angst harbored by many Basques against the herder's lowly social standing.

A few poetic verses on an Idaho aspen declare, in an imprecise translation, "Together, but not neighbors. Brothers, but not family. In Spain, they consider us great men, but here we are nothing."

Today, the Basque herder has largely been replaced by Peruvian or Chilean immigrants. Later generations of Basques — like Bieter's brother, Dave, who is the mayor of Boise — have planted roots in cities across the West.

But Kurt Caswell, who has written several magazine articles on modern sheepherders near McCall, Idaho, said the practice of inscribing trees has continued.

"One of the things that fascinates me is how little has changed," he said. "What it brings home to me is a universal story of immigration, that early generations really occupy a very lonely existence."