Trained giant rats could fight illegal wildlife trafficking by sniffing out shipping containers at transport hubs to detect four common illicit products: elephant tusks, rhino horn, pangolin scales and African blackwood.
The illegal wildlife trade is estimated to be worth up to US$23 billion each year and represents a major conservation threat.
African giant pouched rats (Cricetomys gambianus) are truly rodents of unusual size – they weigh in at 3 kilograms (6.6 lbs) and reach body lengths of 40 cm (16 in). They have a keen sense of smell and a reputation for being gentle and easily tamed.
Previously, Tanzanian non-profit APOPO trained these rodents to sniff out explosives and the pathogen that causes tuberculosis. (APOPO comes from a Dutch acronym that means Anti-Personnel Landmines Detection Product Development in English.)
Researchers from Duke University in the US collaborated with APOPO to train 11 African giant pouched rats to detect scents of the four target wildlife products. All four come from species at high risk of extinction. (Many of the giant rats were named after famous conservationists like Attenborough, Fossey and Irwin).
“Existing screening tools are expensive and time intensive and there is an urgent need to increase cargo screening,” says Dr Isabelle Szott, first co-author of the study published in Frontiers in Conservation Science.
“APOPO’s rats are cost-efficient scent detection tools. They can easily access tight spaces like cargo in packed shipping containers or be lifted up high to screen the ventilation systems of sealed containers,” explains Szott.
To begin training, the researchers rewarded the giant rats with flavoured pellets for performing a “nose poke” into containers with samples of the target wildlife products.
In the next step, the giant rats were introduced to other scents, such as electric cables, coffee beans and washing powder, which are frequently used by traffickers to mask illegal wildlife products.
By the end, eight giant rats could correctly detect the four wildlife species among 146 non-target scents. Critically, these rats could identify the four scents at least 8 months after the training – a cognitive performance on par with dogs.
Szott and colleagues are careful to say that their proof-of-principle study occurred in a controlled setting. They point out that African giant pouched rats would need additional training to navigate the complexities of airports, seaports and other settings where wildlife trafficking occurs.
Still, the authors identify many benefits of pursuing this detection method further.
“Wildlife smuggling is often conducted by individuals engaged in other illegal activities, including human, drug and arms trafficking,” says co-first author Dr Katie Webb. “Therefore, deploying rats to combat wildlife trafficking may assist with the global fight against networks that exploit humans and nature.”
