Many ranchers have cattle out on big pastures or rangeland for summer grazing. It’s not as easy to check on them regularly or to deal with a problem if they are far from corrals, in rugged terrain.

Farmer Bob Herndon lets calves out of a pen in a corral on his farm near Marionville, Mo., May 10, 2006. Herndon, who lost 25 cattle to thieves, begsn branding his animals and patrolling with other ...