A ranger rides an elephant during a demonstration of the art of "bio-detection", to see if it can be used to sniff out explosives, at the Adventures with Elephants game ranch, in Mabula, northwest of Johannesburg, February 20, 2015. REUTERS/Siphiwe Sibeko

By Ed Stoddard

MABULA, South Africa (Reuters) - In the South African bush, elephants are being trained in the art of "bio-detection" to see if they can use their exceptional sense of smell to sniff out explosives, landmines and poachers.

Supported by the U.S. Army Research Office, the project looks promising.

During a recent test run, a 17-year-old male elephant named Chishuru walked past a row of buckets. A swab laced with TNT scent had been stapled to the bottom of one.

Sticking his trunk into each bucket, Chishuru stopped and raised a front leg when he came across the one with the swab. He got the bucket right each time.

And like a sniffer dog, he was rewarded with a treat: marula, a fruit that elephants love.

"An elephant's nose is amazing. Think about mammoths, which had to find food through the ice," said Sean Hensman, operator of Adventures with Elephants, the game ranch 180 km (110 miles) northwest of Johannesburg where the training is being conducted.

The project has a number of roots. Elephants in Angola, which suffered decades of civil war, have been observed avoiding heavily-mined areas, suggesting their trunks were warning them to stay away.

In Hensman's case, he said his father was startled in the 1990s while watching a herd of elephants in Zimbabwe to discover that a female member of the herd had tracked him.

Inspired, his father trained 12 elephants for anti-poaching patrols in Zimbabwe but in 2002 the family lost their three farms to President Robert Mugabe's land seizures and came to South Africa.

U.S. army researchers, who have been involved in the project for five years, say unlike in Hannibal's day, elephants will not be staging a return to the theatre of combat.

"We could bring scents from the field collected by unmanned robotic systems to the elephants for evaluation," said Stephen Lee, chief scientist of the U.S. Army Research Office.

And who has the better nose, the dog or the elephant?

"In our work I don't believe we have a firm conclusion. We would like to better quantify this," Lee said.

But the old adage about an elephant never forgetting seems to have some basis in truth.

"Dogs require constant training while the elephants seem to understand and remember the scent without the need for constant training," Lee said.

(Editing by Andrew Heavens)