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African giant pouched rats (Cricetomys gambianus) could play a significant role in the fight against the illegal wildlife trade. Researchers have successfully trained these three-pound rodents to detect the scents of elephant ivory, rhino horn, pangolin scales, and African blackwood, all of which come from species that are either endangered or threatened due to poaching and illegal trafficking. The results of this research were published on October 30 in a study in the journal Frontiers in Conservation Science.
Study co-author and behavioral scientist Isabelle Szott from the Okeanos Foundation stated, “Our study demonstrates that African giant pouched rats can be trained to detect wildlife products that are trafficked illegally, even when hidden among other scents.”
Utilizing Their Sense of Smell
These rodents have previously been trained for various detection tasks, such as finding explosives and identifying the tuberculosis pathogen. This latest research was conducted at APOPO, a Tanzanian nonprofit that trains rats and other animals for various detection purposes aimed at protecting both humans and animals.
The study involved a team of 11 rats, including individuals named Kirsty, Marty, and Attenborough, all of whom underwent extensive training to recognize specific scents. During the initial phase of training, the rats were conditioned to hold their noses in a hole containing a sample of the target scent. If they successfully performed what the researchers termed a “nose poke,” they were rewarded with tasty rodent treats.
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In subsequent training stages, rats were exposed to various non-target odors, such as coffee beans and laundry detergent—substances that traffickers might use to mask the smell of wildlife products.
“During this discrimination phase, rats learn to focus solely on the scents of wildlife products while ignoring the non-target odors,” Szott explained.
Additionally, the rats underwent memory retention tests where they were reintroduced to scents they had not encountered for several months. Remarkably, they demonstrated a strong capacity for remembering these smells, suggesting their cognitive retention abilities rival those of canines.
During the training, the rats were rewarded for correctly identifying a target by performing a “nose poke” into a designated hole. CREDIT: APOPO. Maria Anna Caneva Saccardo Caterina
By the conclusion of their training, eight of the rats were proficient at detecting four commonly trafficked wildlife species among 146 non-target objects.
“Current screening methods for cargo are both costly and laborious, creating an urgent need for improved detection techniques,” Szott noted. “APOPO’s trained rats represent a cost-effective approach to scent detection, capable of navigating confined spaces within packed shipping containers or accessing high locations such as container ventilation systems.”
Implementing Training in Real-World Settings
The team has suggested that the next phase should involve deploying these trained rats in ports notorious for wildlife trafficking, such as Mombasa in Kenya and Dar es Salaam and Zanzibar in Tanzania, as indicated by data from the United Nations Office on Drugs and Crime.
For this, the rats would wear specially designed vests. These vests would allow the rats to push a small ball attached to the vest, which produces a beeping sound, effectively alerting handlers to the presence of a target scent.
By the end of their training, eight rats were capable of detecting four species commonly targeted in wildlife trafficking among a variety of other substances. CREDIT: APOPO. Maria Anna Caneva Saccardo Caterina
Using their paws, the rats can activate a device on their vests that signals when they detect the scents they have been trained to recognize.
“These vests exemplify the innovative tools that can be applied across various tasks in different environments, such as at shipping ports where wildlife smuggling is prevalent,” said Kate Webb, a neuroscientist at Duke University and co-author of the study.
[Related: How science came to rely on the humble lab rat.]
While the results show promise, the researchers acknowledge certain limitations. The study was performed in a controlled setting that may not accurately reflect the complexities of real-world trafficking environments. To effectively deploy these trained rats, additional research and method development are necessary.
“Wildlife trafficking often occurs in conjunction with other criminal activities, such as drug and arms smuggling,” Webb added. “Utilizing trained rats could contribute to the global efforts against networks that exploit both nature and human populations.”
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