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.
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.”