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Matter of Life & Tech

Rats: Scratch and sniff landmine detection

About the author

Jonathan Kalan is an independent journalist and photographer specializing in social innovations in emerging markets. Based in Nairobi, Kenya, he frequently reports from around the region, specialising in the spaces where technological innovation, social justice and media converge. You can find him on Twitter at @kalanthinks

  • Scratch and sniff
    Apopo is an organisation that trains rats for various purposes including land mine clearance. (Copyright: Jonathan Kalan)
  • Explosive use
    The rats are smart enough to learn a repetitive task and have a remarkable ability to sniff out TNT in the land mines. (Copyright: Jonathan Kalan)
  • Rodent school
    At its training field in Morogoro, Tanzania, up to 37 rats are trained to clear mines each day. (Copyright: Jonathan Kalan)
  • On the leash
    The harnessed rats are led along a rope between two handlers. When they detect explosives, they scratch the ground. (Copyright: Jonathan Kalan)
  • Tasty treat
    If they have correctly identified a mine, trainers use a device to make a clicking sound, which signals to the rat that they have earned a reward. (Copyright: Jonathan Kalan)
  • Dummy run
    After a few months of training, rats are able to quickly ‘clear’ a 5m sq area of deactivated mines. (Copyright: Jonathan Kalan)
  • Light touch
    The rats – which are too light to detonate mines – can clear an area in one day that it would take a human deminer almost two weeks to make safe. (Copyright: Jonathan Kalan)
  • Easy come...
    Rats, unlike dogs or other detection animals, require very little maintenance and can be transported in simple cages on the backs of trucks. (Copyright: Jonathan Kalan)
  • Healthy sniff
    The rat’s sense of smell can be put to other uses. More than 30 of the creatures are now also being used to help detect Tuberculosis in human saliva. (Copyright: Jonathan Kalan)
  • Live test
    TB samples are collected from 17 clinics across Tanzania. So far, the rats have identified double the amount of TB cases as the clinics. (Copyright: Jonathan Kalan)
Meet the giant Africa rats with a remarkable skill, which allows them to safely clear large areas filled with deadly landmines.

When the first of Apopo’s furry and four-legged HeroRats were released into a landmine-ridden field of Mozambique, there was understandable skepticism among the various government officials in attendance.

“In Mozambique we eat rats,” joked Alberto Augusto, the director of Mozambique’s national demining institute, “so it was very strange to see them working and demining. We were thinking to grill them.”

But as the gigantic rodents (bigger than New York City sewer rats) stuffed into tiny harnesses began to sweep back and forth on ropes between their human handlers, stopping every so often to scratch and point out a landmine, it didn’t take long for the crowd to be convinced.

“These are not normal rats,” Augusto declared. “They are very special rats.”

The HeroRats are officially known as Mine Detection Rats (MDRs), specially trained by Apopo, a Belgian NGO that researches, develops and implements detection rat technology for humanitarian purposes like demining.

Landmines continue to be one of the world’s most dangerous weapons, especially in post-conflict countries. Scattered across 78 countries, these weapons of war can remain buried beneath the surface for decades, and their deadly nature does not diminish over time. According to The International Committee of the Red Cross, more than 800 people are killed and 1,200 maimed by landmines every single month - most of them children, women, and elderly.

The sleepy African coastal nation of Mozambique remains one of the most heavily mined countries in Africa. Tens of thousands of landmines were laid during the struggle for independence between 1964-1975 and the civil war that followed for nearly two decades. With no maps of mined territories, Augusto says working to clear the entire country is a “major challenge.”

Yet since Apopo’s rats launched into action in 2006, they’ve successfully cleared more than 6 million square meters of Mozambique’s countryside, uncovering 2,406 landmines, 992 bombs, and 13,025 small arms and ammunitions.

“They are doing a great job,” Augusto says, and with their help he believes Mozambique can be mine free in less than 20 years.

‘Smart, yet dumb’

Removing mines is actually the easiest part of de-mining. The hardest part is finding out where they are.

Over the past two decades, hundreds of millions of dollars have gone into research to improve landmine detection and save lives.

According to Apopo’s CEO Christophe Cox, when the organisation began researching the use of rat technology in the early 90s, dozens of universities were working on new demining technologies like thermal image processing, laser detectors, and so-called Nuclear Quadropole Resonance, a chemical analysis technique.

“We’ve been the only new technology that’s made it to the field out of those hundreds and hundreds of efforts,” claims Cox.  

The problem with introducing new technologies is that there is no one size fits all approach, says Guy Rhodes of the Geneva International Centre for Humanitarian Demining, who has acted as a consultant for organisations in several countries. Specifically, it is very difficult to develop one technology that can deal with the mines of different type, age and scattered in environments that can range from sandy deserts to dense jungles.

“There were big hopes in demining technology” he says. “But there are so many variables that while there may be advancement in one element, there are still major limitations in others.”

Currently, there are myriad ways to detect landmines, including manual techniques – for example, humans with metal detectors and prodders or specially trained detection dogs - and enormous mechanical vehicles like the US State Department’s ‘Hedgehog,’ essentially a modified John Deere tractor with an armored cab and a side-mounted attachment arm for demining tools.

Clearing minefields with these technologies can be a very slow and expensive process. “You can spend a lot of time and money to find out there’s nothing” says Rhodes, “and that’s where these animals are important. Rats are fairly quick tools to raise confidence there aren’t any mines in a large area.”

Rats offer several advantages. First, they are remarkably cheap to source, feed, breed and maintain. The African giant-pouched rats are a widespread indigenous species found across the continent. Because of their poor vision, they depend largely on their acute sense of smell, making them perfect for explosive detection.

The rats can also live up to eight years in captivity, maximizing their return on training investment. Apopo estimates that one rat costs around 6,000 Euros during its lifespan, which translates roughly to 100 euros per month if it’s put to work for just four years.

Second, the rats are “smart” enough to learn repetitive tasks relatively quickly, but –for lack of a better description - dumb enough so that they don’t get bored or distracted easily. Unlike dogs, which are used frequently in demining and explosives detection, rats are not bound to their trainers, making them easy to transfer and handle. Also unlike dogs, rats are too light to accidentally set off landmines.

Lastly, one of the greatest advantages of the rats is their speed. Metal detectors will sound a warning when they sweep across any form of metal, forcing a team to stop and dig regardless of whether it is a tin can or something more sinister. Since rats are trained to sniff for explosives, they yield far less false positives and can even detect plastic landmines. What takes a human deminer almost two weeks, one rat can do in just a day.

Deadly disease

Training a HeroRat takes about nine months, and is done at Apopo’s spacious training fields in Morogoro, Tanzania. From when they are just a few weeks old, the rats are taken from their mothers and “socialised” to become comfortable with humans handlers. Over the next few months, the rats are trained using a process called “click and reward” training. Like Pavlov’s famous dogs they are trained to associate a “click” sound made with a hand-held mechanical device with a food reward - usually mushed bananas and crushed pellets. Once a rat learns that a click means food, they are then taught to associate a specific scent - in this case TNT- with that reward process.

Since rats are nocturnal, they are trained only in the mornings, usually from around seven until nine o’clock in the morning. Gradually, they work their way up from identifying traces of TNT in a “contaminated” 3 sq m (32 sq ft) area, to clearing 5 sq m (54 sq ft) and then 10 sq m (108 sq ft) areas with de-activated landmines below the surface.

To earn the International Mine Action Standards Accreditation and be certified for mine action, the rats must pass a blind test, clearing an 800 sq m(8,600 sq ft) field over two days. They must find one 100% of the mines, with only two false positives. So far, 300 rats have been cleared for action.

Yet while rats might be faster than metal detectors and cheaper and less fussy than dogs, they are not for every situation.

It’s a novel approach that plays a significant role in a certain context,” says Guy Rhodes, “but it may not be a tool that is applicable everywhere. With a detector, you stick a battery in and go. With animals, you need a lot more confidence.”

Some people are scared off by the additional care that rats require- like constant re-training, veterinarian services, transportation and feeding. Then, there are climates- like deserts- where rats cannot work.

Other challenges come with the type of demining required.

“Many mine problems are not mine problems, but [unexploded ordinance] problems on the surface, which need demolition teams and not search animals,” says Cox.

Even so, Apopo’s rats are currently deployed in Thailand and Mozambique, and they are conducting technical surveys in Cambodia and Angola. By combining the rats with existing technologies- metal detectors and other detection and diffusing tools- they are proving themselves to be fast and effective on the job.

The organisation is also discovering new uses for the rat’s powerful noses and easy trainability. In Tanzania, the rats are being used to detect Tuberculosis in human saliva samples- a disease which kills almost 40 times as many people than landmines each year.  The rats detect twice as many TB cases as the current methods, acting as a second-line detection system. As with landmines, the rats are far quicker; they can evaluate more samples in then minutes than a lab technician can do in a day.

“I’m really confident with the promise of the rats, and the potential impact which we can make,” says Cox. But convincing everyone else still isn’t easy.

“It wasn’t easy to penetrate the demining world with rats because it’s military minded, and the health world is equally challenging,” he says. “We have to continue researching and publish and convince the policy makers.”

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