FROM A BLUFF over looking a sunbaked valley outside Farmington, New Mexico, Aaron Facka and Michael Dax watched a black helicopter soar, thrumming loudly as it swooped low over the landscape. Inside, three men searched the grasslands for the white specks of pronghorn, the antelope-like creatures that inhabit the Western plains of North America.
It was early March, cloudless and warm, but Facka and Dax, who both work for the Wildlands Network, an environmental nonprofit, were nervous. The men in the helicopter worked for a company that specializes in capturing wildlife for biological research. Each time they spotted a pronghorn, the pilot flew close enough for a colleague to fire a gun that released a net, trapping the animal so that it could be fitted with a GPS collar. The collars provide data about herd movements, habitat use and population numbers, but the stress of trapping puts pronghorn at risk of death from
