Africa's sniffer rats to the rescue

By Britt Collins March 23, 2021
APOPO's Magawa wearing his PDSA Gold Medal APOPO's Magawa wearing his PDSA Gold Medal

They famously helped clear former warzones of landmines. But, as Britt Collins reports, Africa’s sniffer rats could soon be the latest recruits in the fight against both illegal wildlife trafficking and Covid-19.

An elite squad of sniffer troops are hard at work, scurrying through boxes scattered around a field in Tanzania’s southern highlands. APOPO, the Morogoro-based non-profit that pioneered using African giant pouched rats to find landmines, is teaching the rodents to detect the smell of pangolin scales and other illegal wildlife products as part of Africa’s never-ending battle against international smugglers. 

Known for sniffing out buried explosives with great success, these forest-dwelling rodents, whose sense of smell rivals that of bloodhounds, could soon turn their mighty noses to protecting other animals being smuggled out of Africa for the illegal wildlife markets of Asia. 

Unlike sniffer dogs, the rats, which are only three-foot long from nose to tail, can squeeze into tight, hard-to-reach spaces and scramble up shipping containers and through cargo stuffed with poached pangolins or other illicit animal body parts. 

Blessed with super-sensitive nostrils to relocate squirreled-away food and navigate burrows through the dark, the nocturnal mammals are able to sniff out pangolin scales, which smugglers often hide beneath other strong-smelling products, such as coffee or spices, to throw customs officers off the scent.  

‘Rats are extremely intelligent and quick to learn. So far, our rats have been trained to detect pangolin scales and an endangered ebony wood, which is illegally logged in Madagascar,’ said Dr Cindy Fast, APOPO’s head of training and behavioural research.  

‘Dogs have been doing this type of work for decades, but they’re quite expensive and struggle in the hot and dry climate in Africa.’

The docile animals, sometimes known as Gambian pouched rats, are easy to train and transport between locations, resistant to many tropical diseases and well-adapted to the environments they work in. 

Cindy Fast and sniffer rat

Life savers

APOPO’s ‘HeroRATs’, so named because of their life-saving work clearing landmines, are remarkably effective. Magawa, the charity’s most successful mine-sniffer, recently made international headlines for receiving the PDSA animal charity’s Gold Medal for bravery. The seven-year rodent has sniffed out 39 landmines and 28 munitions in Cambodia since he was trained by the charity.  

Over 20 years, Africa’s sniffer rats have unearthed more than 108,000 landmines, remnants of war buried in the earth in some of the world’s deadliest post-conflict zones.

According to APOPO, one rat is capable of searching a field the size of a tennis court in 20 minutes, which could take a human de-miner, who must rely on metal detectors that send constant false alarms, as much as four days. Magawa’s bomb-detecting colleagues are still working tirelessly all over the world to protect people from deadly landmines.

They were recently tasked with clearing minefields inside the Sengwe Wildlife Corridor, the largest conservation area in the world spanning Zimbabwe, South Africa and Mozambique. This saved the lives of not only the local populations and livestock but also elephants and other wildlife that migrate between the region’s economically important reserves and parks. 

Hidden heroes

Hand-raised by humans from infancy, the mega rodents are trained to paw the ground when they smell TNT and are given a treat for every successful landmine detected.

They work for their favourite snacks, including bananas, peanuts, sun-dried sardines and avocados.

Too small to set off the landmines, to date no animals have lost their lives in the line of duty.  

Many people assume that rats are used for these dangerous missions because they’re inexpensive and considered expendable by researchers.

But APOPO was founded by an animal-loving humanitarian and its rats are treated as the heroes they are, and given celebrity names, such as Bowie, Blondie, Bob Dylan, Jane Goodall and Maya Angelou. 

Bart Weetjens, a Dutch industrial engineer, came up with the idea in 1995 when he was exploring solutions for the global landmine problem.

As a kid growing up in Antwerp, Belgium, he kept rats as pets and knew how smart, social and trainable they were.  

When Weetjens came across an article about the use of gerbils for scent detection, he wondered if rats could be taught to recognise the chemical compound of explosives.

He consulted Professor Ron Verhagen, a rodent expert at the University of Antwerp who had worked in Africa for many years, and he recommended African giant pouched rats for the job.

During his time in Tanzania, Verhagen had even seen a villager walk one on a lead.

These critters, natives to the sub-Saharan region, were already adapted to the environmental conditions most in need of mine-clearance support, which at the time were Mozambique and Angola. 

Crime solvers

The Endangered Wildlife Trust (EWT), a conservation organisation based in South Africa, works collaboratively with APOPO on the wildlife-scent detection project.  

‘Having seen APOPO’s amazing work using African pouched rats in other settings, we thought that success could be extended to help fight against wildlife crime,’ said Ashleigh Dore, EWT’s project manager.

‘We originally sourced funding from US Fish and Wildlife Service’s ‘Combating Wildlife Trafficking Program’ and then the UK government through the ‘Illegal Wildlife Trade Challenge Fund’ to test whether the rats could detect wildlife specimens. 

The project, currently funded by Wildlife Conservation Network, is truly ground-breaking.’ 

APOPO is training a squad of pouched rats, nine seasoned sleuths and eight newcomers, for wildlife-scent detection.

‘We’ve just started exploring, but have a lot of evidence suggesting our rats can quickly learn new scent targets while remembering those they’ve already learned,’ explained Fast. 

‘The rat moves into the training area, a mock shipping environment, where boxes have been placed.

'Some have been loaded with the target scent hidden inside, while most boxes contain non-target ‘dummy’ scents.

‘The rats have generalised well to scales collected from more than one pangolin. We haven’t trained or tested them with live pangolins or other pangolin products yet.’

One of the difficulties has been access to pangolin parts for training.

Scales are tightly regulated and it has been challenging to acquire samples from all four African species of pangolin.

‘Whether or not the different species smell noticeably different to the rat is a question we intend to answer in the future,’ Fast added.

‘With the promising results we’ve gathered so far, we hope to begin field training and tests next year.’ 

After successful training, the super-sniffer detectives will be deployed at airports, national parks, seaports and borders, initially in Tanzania, to scour shipments of pangolins.

Wildlife trafficking has continued during the Covid-19 pandemic and pangolins, whose scales are used in traditional Chinese ‘medicine’ for a variety of unproven treatments, are in a constant state of crisis.  

Demand for the scales of the shy, nocturnal animals, which look like scaly armadillos but are actually related to bears and dogs, now exceeds that for elephant tusks or rhino horns.

The International Union for Conservation of Nature (IUCN) estimates that a pangolin is taken from the wild every five minutes, which equates to the loss of more than one million animals in the last decade, pushing all eight species toward extinction.   

The team of pangolin-sniffing rats could soon be patrolling ports and borders.

‘Our goal is to train and test the rats within a real seaport environment next year,’ said Fast.  

Trainer rat

Backpacking rats

In a series of training stages that increasingly resemble real-world conditions, the rats are fitted with backpacks that hold a tiny video camera and small beeper, to which they quickly became accustomed to wearing.

‘They have all been trained to trigger a microswitch by pulling a small ball attached to their harness when they detect the target scent,’ Fast explained.

This makes it possible for the rat to alert the handler when it has found something, even if the handler is out of view.’

Someday these unlikely heroes could be trained to search for other widely trafficked wildlife contraband, such as lion bones, rhino horns and elephant tusks.  

Disease detectors

But it’s not just other animals the rats are helping save.

They are also being used to detect tuberculous (TB) in humans and could soon be used to sniff out Covid-19. 

APOPO recently received a $725,000 grant from the Belgian government to train rats to detect Covid-19 in the Mozambican cities of Maputo, Matola and Marracuene.

The scheme, which is being run in partnership with the Mozambican National Health institute (INS) and the Eduardo Mondlane University in Maputo hopes to replicate the rats’ incredible work in detecting cases of TB. 

APOPO’s rats have already proved one of the best tools that scientists have in detecting early cases of the infectious disease, which kills 1.4 million people a year.  

The rodents can sniff more saliva samples for TB in 10 minutes than a lab technician can analyse in a day.

They’ve proved so successful in Tanzania, Mozambique and Ethiopia, where they’ve been used, that they’ve increased detection rates by 40 per cent, identifying 20,000 cases that would otherwise have been missed, and preventing the onward transmission to an estimated 160,000 more people.  

Worthy investment

Rats don’t come cheap. It costs around $7,000 to train each of the charity’s 300 rats, and takes around nine months before they are ready to be deployed around the world.

The rats are also shipped to Thailand, Cambodia, Laos and Vietnam to detect landmines there. 

Unlike dogs, which are notoriously tricky to train, most African pouched rats graduate from scent-detection school with flying colours.

‘They’re truly a pleasure to work with. And if you’re lucky, you’ll even get a sweet lick or two,’ said Fast, who spent a decade studying animal cognition with all sorts of animals, like horses, pigeons and hermit crabs.

She has a soft spot for rats and even adopted a few.

‘They’re fun, sociable and inquisitive creatures, so it’s hard not to develop bonds with them. Knowing the rats will be well-cared for in new homes and saving lives makes it easier to say goodbye when they graduate from training.’ 

Fast recalled visiting the minefields in Cambodia, witnessing a recently graduated rat as it successfully discovered explosives.

‘When the de-miner moved in, it was confirmed that there was an unexploded ordinance buried in the ground a few feet where I was standing. It gave me chills, but I felt like a proud parent.’  

Sniffer rat

Working conditions

The sniffer rats only work mornings, as its too hot to work midday.

Like everyone else, they have weekends off, chilling out in the playpens with their rodent friends and hanging out with their handlers.  

After five or six years, or once they’re no longer keen to work, the rats, who can live up to nine years in captivity, spend their golden years in large enclosures, furnished with clay nesting pots, climbing ropes, running wheels and tunnels.

The retired rats get fresh locally sourced produce, weekly vet inspections and continued socialisation with the animal-welfare team members. 

Such thoughtfulness underscores every aspect of their lives until the end.

‘We began the tradition of burying the HeroRATs that passed away in the early days,’ explained Fast.

‘Our staff in different countries have different cultures, and they each honour the animals that have passed in their own way. In Tanzania, our staff will sing a song or two, while in Cambodia they hand-build wooden grave markers and take a moment of silence.’

Friends, not foes

Few mammals are so reviled and persecuted as rats – which are seen as being dirty, diseased, invasive.

But rats are increasingly being used around the world for jobs previously carried out by dogs and scientists. 

In the Netherlands, for example, police forensics teams use common brown rats to find gunpower residue to solve crimes.

Several animal-therapy and assistance programmes for autistic kids, elderly and disabled people in the United States have traded in their companion dogs for domesticated rats. 

Many other jobs that are currently done by dogs, such as drug enforcement, border patrol, rescue missions to sniff out victims of earthquakes and cadaver searches, could be done by the rodents in the near future.  

Rats may be known as vermin, and considered expendable in most parts of the world – up to 100 million rats and mice a year are killed in American lab experiments alone.

But from detecting landmines to Covid-19, APOPO is just scratching the surface of the extraordinary things these much-maligned creatures can do.

To sponsor a life-saving rat for around $12.50 a month, see apopo.org.