The Peregrine falcon was little more than a pinprick in the sky, a tiny black speck set against roiling thunderheads. Nate watched the bird circle in the ellipse of a lazy thermal spiral. The falcon was so high in the air it took a knowing eye to see it. But the ducks knew the falcon was there because none had attempted to fly.

Nate nodded to himself and tugged on the end of an empty burlap sack he’d tucked through his belt. He flipped the sack over his shoulder to keep it out of the way, and approached the willows in silence.

Before he entered the brush, he paused and looked over his shoulder and scanned the terrain. His small house was far below in the river valley, his Jeep parked next to it. The old structure was bordered by massive old river cottonwood trees with gnarled gray bark and skeletal limbs. Because most of the leaves were gone, he could see his clapboard mews for housing falcons, and an upturned flat-bottomed boat on the bank of the river he used for crossing. On the east side of the North Fork, a steep red wall rose sixty feet into the air. The top was flat and dotted with scrub. Beyond the flat the country rose at a gentle pitch in a series of waves and folds until it melded into the multicolor pockets of aspen and then the dark timber fringe of the mountains. Rounded peaks above the timberline were dusted with the fresh first snow of the fall.

To the west was an undulating treeless sagebrush flat that continued for miles. A single two-track road cut through the sagebrush and meandered its way through cuts and draws to the stone house. There was no other way in, and if someone was coming he could see them from miles away. On the sides of the sections of road out of his vision, he’d installed motion-detection sensors and hidden closed-circuit cameras that would broadcast images of visitors into his house well before he could see them with his naked eye or through his binoculars.