In the fight against illegal wildlife trafficking, an unexpected group of heroes has emerged: African giant pouched rats. Known for detecting landmines and diagnosing tuberculosis, these rats are now being trained to sniff out wildlife products like pangolin scales, rhino horn, and elephant tusks. Their keen sense of smell and agility could transform anti-trafficking efforts at ports around the world.

A billion-dollar market

The illegal wildlife trade is a multibillion-dollar global industry that endangers species, threatens ecosystems, and fuels other criminal activities like human trafficking and arms smuggling. Among the animal species most frequently trafficked are pangolins, elephants, and rhinos. Combatting this black market is no easy task. Contraband is typically hidden in complex cargo shipments, making detection challenging and costly.

“Traffickers always come up with new material to conceal their contraband. This could be either strong-smelling items to conceal the wildlife or items that can be used to conceal wildlife and contraband from visual detection such as X-ray or CT machines,” says Kate Webb, an assistant professor at Duke University and author of the new study, in an email to ZME Science.

Current screening methods have their own limitations. Typically, they are expensive, labor-intensive, and not always effective at detecting hidden organic materials. This has led to a growing interest in scent-detection animals.

So, for their keen sense of smell, adaptability, and resilience in harsh environments, we turn to African giant pouched rats. They often perform tasks that are too risky, costly, or technically challenging for humans and machines. In regions affected by decades of landmine contamination, the rats have safely cleared land, making it habitable again. Elsewhere, their tuberculosis detection skills have accelerated diagnoses in communities where healthcare resources are limited.

Now, it’s time to take on wildlife trafficking.

Sniffing out trafficking

In a proof-of-principle study, researchers at APOPO, a non-profit in Tanzania known for training rats to detect landmines and tuberculosis, set out to test whether the rats could be trained to recognize the scent of pangolin scales, rhino horn, elephant tusks, and African blackwood. Over months of rigorous training, the rats demonstrated a remarkable ability to sniff out all four target species. The rats could even distinguish them even among a mixture of non-target items commonly used by traffickers for concealment.

“The biggest advantages of the rats are their relatively short training time, flexibility in working with different trainers, and cost-effectiveness. Each detection rat costs around 7,000 to 8,000 USD and it takes approximately 9 months to train for existing operations such as mine detection and TB detection. The cost of other detection technologies such as X-ray and CT scanners varies substantially but is quite high (30k to 1.2 million USD). Dogs often have to work with the same handler whereas our rats are easily transferable between trainers,” adds Webb.

The research, conducted over four years, involved training 11 rats to detect scents associated with four wildlife products. The rats were named after conservationists such as David Attenborough, Steve Irwin, and Dian Fossey.

Inquisitive sleuths

Initially, researchers exposed the rats to the scent of pangolin scales and African blackwood, training them to identify and hold their nose over the scent source for a few seconds to receive a reward. The subsequent phases introduced more challenging conditions. Now, non-target smells like coffee beans or electrical cables were added to test the rats’ abilities to distinguish the correct scent.

“Teaching rats to detect wildlife even within such complex mixtures requires advanced training, so we exposed the rats to a large variety of items. Importantly, these rats performed exceptionally well when faced with this challenge, detecting wildlife targets and ignoring nearly 150 non-target items, including biologically relevant odors such as the smell of another rat (e.g., bedding) or tasty food items (e.g., peanuts),” Webb tells ZME Science.

The rats performed admirably in these tests, correctly identifying wildlife scents even when these were concealed among non-target items. Through positive reinforcement, the rats were gradually conditioned to recognize additional scents, including rhino horn and elephant ivory. The rats not only successfully detected all four wildlife scents but did so with remarkable accuracy and had a very high “graduation rate.”

“All of our rats are very inquisitive and trainable! The attrition rate across APOPO’s operational tasks is very low: over 95% of the rats we train are successfully deployed to an operational task.”

They’re being used in the real world

It’s not easy to train the rats, but researchers were helped by officials in Tanzania.

“We trained rats to detect species with the highest levels of protection which means obtaining samples legally takes coordination across organizations. For example, we were very fortunate to work with the officials at the Dar Es Salaam Zoo who helped us secure our initial pangolin samples! Our ongoing work involves working alongside multiple stakeholders to ensure we best prepare the rats to encounter different quantities of wildlife targets.”

The trained rats are now being tested for real-world applications. At the Dar es Salaam port, where over 90% of Tanzania’s international trade passes through, APOPO ran operational trials with the Tanzanian Wildlife Management Authority (TAWA) as independent observers. “There is great interest in the rats due to their cost advantage, and we also had interest from ports in Singapore and France,” says Webb.

The next step involves equipping the rats with custom vests containing beepers, which the rats can activate upon detecting a target scent. This hardware, developed specifically for port environments, could allow the rats to alert handlers independently. With their paws, the rats would pull a small ball attached to their vest, and this would emit a beeping wound. “The vests are a great example of developing hardware that could be useful across different settings and tasks, including at a shipping port to detect smuggled wildlife,” says Webb.

Fighting wildlife trafficking won’t be easy

The results may vary when the rats encounter real-world complexities. Additional training and trials are necessary, particularly when it comes to deploying rats in more varied environments. They need experience dealing with the noise and the sheer volume of scents present. But, given the scale of the problem, any additional weapon is welcome.

“We see the rats as an additional and complementary tool to fight the illegal wildlife trade. They are cost-effective, which makes them an attractive option, especially in developing countries. In addition, they can screen areas at shipping ports that dogs are unable to access (for example, by lifting them high to the air vents of containers). The more pressure we can apply to trafficking networks, the bigger the cost to them to operate! Developing new and innovative methods to fight the illegal wildlife trade signals to poachers and smugglers that we are invested and steadfast in our fight against all forms of illicit trade,” Webb mentions.

The hero rats

It gets even more promising. There’s often significant overlap between wildlife smuggling and other types of illegal activities. Researchers say the rats could be used to fight other types of crime as well.

“Wildlife smuggling is often conducted by individuals engaged in other illegal activities, including human, drug, and arms trafficking. Therefore, deploying rats to combat wildlife trafficking may assist with the global fight against networks that exploit humans and nature. APOPO is working with various stakeholders at the port to determine which odors the rats should be trained on to optimize resources and complement existing tools. The rats can certainly learn to detect additional items as needed!”

APOPO’s “hero rats” have now proven their worth across multiple applications, and wildlife detection may be their next impactful project. With potential deployments on the horizon, these rats may soon be integral players in disrupting trafficking networks and curbing the illegal wildlife trade.

As APOPO’s hero rats begin their role in detecting trafficked wildlife, they bring a novel approach to conservation efforts and illustrate the power of unconventional allies in fighting global challenges. Their successful training not only holds promise for disrupting illegal wildlife trade but also signals a step forward in the creative, multifaceted strategies needed to protect vulnerable species.

In a world where human actions have endangered so many species, the hero rats offer an important reminder that we also have the weapons to stop wildlife trafficking — even though sometimes we need allies. If you want to support this type of project, you can also “adopt” a rat online at www.apopo.org.

The study “Ratting on wildlife crime: Training African giant pouched rats to detect illegally trafficked wildlife” was published in the journal Frontiers in Conservation Science. http://dx.doi.org/10.3389/fcosc.2024.1444126