Updated May 7, 2025 at 2:23 PM CDT
A rat named Ronin has set a new Guinness World Record by detecting 109 land mines in Cambodia over the last four years.
Ronin is an African giant pouched rat who works with APOPO, a nonprofit that trains rats to detect unexploded ordnance, land mines and tuberculosis. APOPO’s rats have cleared more than 122 million square meters of former minefields and found more than 169 thousand explosive remnants.
So, why rats?
These rats are nocturnal with a highly evolved sense of smell that helps them sniff out explosives, said Cindy Fast, head of training and research at APOPO.
African rats are larger than the familiar brown rats found here in the U.S., which helps them navigate large areas without getting tired, Fast said.
African giant pouched rats can live from 8 to 10 years old — another advantage.
“That means after we take a year or so to train them up to the super high level of perfection that’s needed to do this dangerous work, they still have a really long working career ahead of them,” Fast said.
Rats ignore scrap metal when they search old minefields, which speeds up the process compared to humans, Fast said.
Though they’re bigger than the rats scurrying around your trash can, African rats are too light to detonate the pressure-sensitive mines, she said.
“For us, our rats are like our heroes and they’re our colleagues, so we tried to treat them with respect and dignity, and we wouldn’t do this work if there was a threat that they could be harmed,” Fast said. “None of our rats have ever been harmed in the line of duty.”
The origins of bomb-sniffing rats
Back in 1997, an engineering student received a class assignment to solve a problem in the world, Fast said. At the time, Princess Diana was raising awareness about land mines.
“He came across a paper where someone had taught hamsters or gerbils to detect explosives and said, ‘Well, if you could do it with hamsters or gerbils, I’m sure you can do it with rats,’” Fast said. “And the idea was born and just went from there.”
How does Ronin the rat do it?
There are more than 100,000,000 landmines still in the world, and they kill or wound people at a rate of around 15 per day.
With a red harness on, Ronin walks back and forth between two handlers, Fast explains. When he reaches one, they both step half a meter forward. Ronin then searches that area.
“If he smells explosives, Ronin communicates that to his handlers by just scratching at the ground,” Fast said.
For Ronin and his rodent colleagues, finding the landmines is a puzzle to solve in exchange for a treat. At risk of anthropomorphizing, Fast said the rats enjoy the work.
“Ronin was always just a very quick learner. He’s not distracted at all when he’s searching. He’s very diligent. He walks quite quickly,” Fast said. “When he smells explosives, he lets us know right away, scratching.”
On APOPO’s website, people can adopt Ronin or the other hero rats. As a nonprofit, the organization relies on support from the public, Fast said.
One way to help is to sponsor one of the rats’ work, whether it’s Ronin in Cambodia sniffing out land mines or another rat identifying people who have tuberculosis in different parts of the world.
Julia Corcoran produced and edited this interview for broadcast with Todd Mundt. Allison Hagan adapted it for the web.
This article was originally published on WBUR.org.
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