Why don't we use them to protect elephants from poachers?

There is nothing a mother elephant will not do for her infant, but even she cannot protect it from bullets. About a year ago, poachers attacked a family of forest elephants in central Africa. The biologist who witnessed the attack told us that wildlife guards were completely outgunned. In the end, an elephant mother, riddled with bullets and trumpeting with pain and fear, was left to use her enormous body to shield her baby. Her sacrifice was for naught; the baby was also killed.... This mother and child were just two of the tens of thousands of forest elephants that have been butchered over the past decade. A staggering 62 percent vanished from central Africa between 2002 and 2011, according to a study we have just published with 60 other scientists in the journal PLoS One. It was the largest such study ever conducted in the central African forests, where elephants are being poached out of existence for their ivory.