PICEANCE CREEK — The frenzied cows circled recklessly in a dust cloud, desperately searching for their missing calves amid a tangled maze of sagebrush on a mountain slope.

Their high-pitched wails were like nothing Susan Robinson had ever heard in five decades of working her mountain ranch in Rio Blanco County, and the pitiful bellowing left her frightened and nauseous.

Boot prints in the dirt told her what she had already suspected: Someone had stampeded her prime Black Angus cattle through a barbed-wire fence, driving them away from windmill-fed water holes and leaving them parched, injured and separated.

It was the latest in a series of what Robinson considers cruel provocations aimed at forcing her and her livestock off land the family has ranched for more than a century.

The Robinsons have used barbed wire, guns and gumption to protect their land and livestock since the early 1910s, when Joseph Robinson drove thousands of sheep from Paraguna, Utah, to Rifle. They survived the sheep and cattle wars, the Depression and countless trespassers.

But now the family faces a new adversary, one with deep pockets, a high-powered Denver law firm and a determination to explore and drill beneath the pastureland.