Paw Patrol: Rodents could soon rat out wildlife traffickers

A team of researchers have trained these highly intelligent rodents to sniff out illegally trafficked wildlife products such as pangolin scales, rhino horn, ivory and African blackwood, often smuggled through airports, seaports, and other border crossings. 

"We can train African giant pouched rats to detect illegally trafficked wildlife, even when it has been concealed among other substances," said Dr Isabelle Szott, a researcher at the Okeanos Foundation and first co-author of the study published in Frontiers in Conservation Science. 

"Their small size, agility, and ability to work in tight spaces make them an ideal solution for combating wildlife crime."

"The rats also continued to detect the wildlife targets after not encountering that species for a long period," said first co-author Dr Kate Webb, assistant professor at Duke University, referring to their ability to remember targets for several months after the training.

The rats underwent several training stages at Apopo, a Tanzania-based, non-profit organisation that provides low-tech, cost-efficient solutions to pressing humanitarian challenges.

"During indication training, the rats learned to hold their noses for several seconds in a hole in which the target scent was placed. When they correctly performed this 'nose poke,' they were rewarded with flavoured rodent pellets," said the researchers.

In the next step, the rats were introduced to non-target odours. These included electric cables, coffee beans, and washing powder—objects frequently used to mask the scent of wildlife in real-life trafficking operations. 

"During the discrimination stage, rats learn to only signal the odours of the wildlife targets while ignoring non-targets," Szott said.

The rats were also trained to remember smells. At the end of their retention training, they were re-introduced to scents they'd not encountered for five and eight months, respectively.

Despite months of non-exposure, the rats showed perfect retention scores, suggesting that their cognitive retention performance resembles that of dogs.

Trafficked products such as pangolin scales, rhino horn, ivory and African blackwood fuel Africa's illegal wildlife trade, valued at an estimated $7 billion to $23 billion annually. These high-value items are central to the illicit market, threatening wildlife conservation and biodiversity. 

Pangolins, the most-trafficked mammal currently, are targeted for their scales in traditional medicine. Rhino horn, prized for its supposed medicinal value, and ivory, used for carvings and fuel poaching, which decimates rhino and elephant populations. 

Read: Giant rats increase their attack on tuberculosis in Tanzania

African blackwood, sought for musical instruments, faces unsustainable harvesting. These products endanger wildlife, fuel organised crime, and harm local communities. Strong conservation efforts and global cooperation are crucial to combat this trade.

"Existing screening tools are expensive and time intensive, and there is an urgent need to increase cargo screening. 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," Szott explained.

Scientists say the next step is to train the rats to operate in ports where wildlife trafficking occurs. The rats will wear custom vests equipped with a small ball at the chest, which they can pull with their front paws to trigger a beeping sound. This alert will signal their handlers when the rats detect illegal wildlife products.

"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," said Webb.

"This proof-of-principle study demonstrates that rats can successfully identify trafficked wildlife. This does not mean it comes without limitations." 

For example, the study was conducted in a controlled environment, which does not reflect the settings where wildlife is commonly trafficked or screened by scent-detection animals. New methods need to be developed to deploy rats for this task, the researchers pointed out.

"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," Webb said.