SHEEP, you may be surprised to learn, are not as dumb as they look. Some people might even describe them as shrewdly calculating, remarkably crafty animals with fierce independent streaks. Given the slightest opening, for example, they will quit a herd, striking out in small, enterprising bands for the high-desert plains — ungulate fugitives in a promised land of sagebrush and cactus — sometimes never to be seen again.

“They’re good animals if you take care of them,” said Henry Etcheverry, as we bounced along a dusty two-track in the Minidoka desert near Rupert, Idaho, 160 miles southeast of Boise, tracking an errant herd. “But take my word for it: they’ll clean your clock if you don’t.”

Mr. Etcheverry is one of the last Basque sheepmen left in the American West, where there were once hundreds, if not thousands, like him. He learned the business from his father, Jean Pierre Etcheverry, who emigrated from the Basque Country, a region in the Pyrenees Mountains comprising parts of southern France and northern Spain, in 1929. Back then sheep outnumbered Idahoans seven to one, a peak that coincided with the tail end of Basque immigration to the western United States. Tens of thousands settled in Idaho, Nevada, California, Utah and Wyoming, many finding work in the sheep trade or establishing boardinghouses and restaurants catering to Basque herders. Though a precise tally is elusive, Basques once roamed Idaho’s sheep ranges in formidable numbers. Today, just two or three remain.

“I’m the last of the Mohicans,” said Mr. Etcheverry, 63, a sturdy, affable man with gray caterpillar eyebrows and wind-chapped skin who learned to drive a pickup at age 8 and run his own herd by 12. His father started out in the Minidoka desert, camping in the brush for months on end with little besides a horse, a couple of dogs and a few hundred sheep for company, the loneliness compounded by a relentless, howling wind. As Basque herders prospered, they tended to gravitate to less solitary occupations. All of Mr. Etcheverry’s herders these days are Peruvian.