African giant pouched rats (Cricetomys gambianus) could be the next line of defense in the illegal wildlife trade. A team of researchers have trained these three-pound rats to pick up the scent of elephant ivory, rhino horn, pangolin scales, and a small tree called African blackwood. All of these animals and plants are listed as threatened or at a high risk of extinction and are illegally trafficked. The findings are detailed in a proof-of-principle study published October 30 in the journal Frontiers in Conservation Science.
“Our study shows that we can train African giant pouched rats to detect illegally trafficked wildlife, even when it has been concealed among other substances,” study co-author and Okeanos Foundation behavioral scientist Isabelle Szott said in a statement.
Sniffing things out
Previously, African giant pouched rats have been trained to detect explosives and even the pathogen that causes tuberculosis. This new study to test their ability to detect wildlife scents was conducted at APOPO. The Tanzania-based, non-profit organization aims to protect both people and animals with trained rats and other scent detection animals.
It included 11 rats–Kirsty, Marty, Attenborough, Irwin, Betty, Teddy, Ivory, Ebony, Desmond, Thoreau, and Fossey. All of them underwent several stages of smell training. During indication training, they learned to hold their noses for several seconds while inside of a hole where the target scent was placed. If the rat correctly performed what the team called a “nose poke” they were rewarded with flavored rodent pellets.
[Related: Rats may have imaginations.]
Next, the rats were introduced to some non-target odors. This included coffee beans, electric cables, and washing powder. Wildlife traffickers often use these objects to mask the smell of wildlife.
“During the discrimination stage, rats learn to only signal the odors of the wildlife targets, while ignoring non-targets,” Szott said.
The rats were also trained to remember smells. At the end of this training, they were re-introduced to scents that they hadn’t encountered not encountered for five and eight months, Even with such a long period of non-exposure, they showed high retention scores. Their cognitive retention performance is potentially as strong as a dog’s.
Eight rats were able to identify four commonly smuggled wildlife species among 146 non-target substances by the end of the training.
“Existing screening tools are expensive and time intensive and there is an urgent need to increase cargo screening,” said Szott. “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.”
Getting rats on the job
According to the team, a good next step is to develop ways for the rats to work in the ports where smuggled wildlife is trafficked. These include the ports of Mombasa, Kenya, and Dar es Salaam and Zanzibar in Tanzania, according to data from the United Nations Office on Drugs and Crime.
To do this, the rats would be outfitted with custom-made vests. They can use their front paws to put a small ball attached to the chest of the vest, which emits a beeping sound. This way, the trained rats will be able to let their handlers know when they detect a target.
With their front paws, they will be able to pull a small ball attached at the chest of their vest, which emits a beeping sound. This way rats will be able to alert their handlers when they detect a target.
“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,” study co-author and Duke University neuroscientist Kate Webb said in a statement.
[Related: How science came to rely on the humble lab rat.]
While the rats in the study could successfully identify the scents related to trafficked wildlife, there are still some limitations. The study was conducted in a controlled environment, so it is not reflective of the real world settings where wildlife is commonly trafficked or screened by scent-detection animals. In order to deploy these rats, new methods need to be developed, according to the team.
“Wildlife smuggling is often conducted by individuals engaged in other illegal activities, including human, drug, and arms trafficking,” said Webb. “Therefore, deploying rats to combat wildlife trafficking may assist with the global fight against networks that exploit humans and nature.”
