In 1981, Doug Johnson began studying the way grazing animals move around their pastures. Twenty years later, he added a new twist.

“We started using GPS collars on animals,” says Johnson, an Oregon State University rangeland researcher.

Although his GPS technology is not ready for practical application, it could be used to compare the grazing strategies of different species, examine the effects of mixed-species grazing and identify grazing efficiencies, says Johnson.

“Ranchers have a good idea of their animals' behavior,” he says. “We have been trying to ‘put numbers to the process’ and compare different breeds and species. For example, we have found that cattle select the least-energy-cost pathways between feeding stations and water. This means that we can predict routes that livestock are likely to use and plan range improvements more effectively.”

Because commercial GPS collars cost $4,500, Johnson's research team builds its own. The collars can collect a location point every second and have remote downloading capability. They're attached in the field or in an alley or chute.

“We try to be as gentle as possible since we are examining normal behavior and try to keep the animals calm.”

He has studied cattle, goats and elk. The cattle study logged each animal's location, with the date and time, every 30 seconds. He could see when an animal came to water and when it left, the amount of time it spent loafing, where it went and how it got there. Herd leaders and followers could be distinguished from their movements.