“You are never more than six feet away from a rat,” so the saying goes. Though here at BBC Science Focus we’ve concluded that this measurement is incorrect, it might soon be accurate for those involved in the illegal wildlife trade (IWT).
A team of researchers have trained African giant pouched rats to pick up the scents of endangered animal anatomy – pangolin scales, elephant ivory, rhino horn – in an effort to provide a low-cost detection system to prevent illegal smuggling.
The – ahem – rat pack can even identify these items when concealed among other substances, and have been shown to remember the smells after months of non-exposure.
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Why rats?
This isn’t the first time APOPO, the Tanzania-based, non-profit tasked with conducting the study, have recognised a potential for a super-rat workforce.
The organisation looks to provide low-tech, cost-efficient solutions to pressing humanitarian challenges throughout Africa, and have previously trained packs of their ‘HeroRATS’ to detect landmines and the pathogen that causes tuberculosis.
Dr Isabelle Szott, first co-author of the new study published in Frontiers in Conservation Science, helped identify the rat’s potential for IWT detection.
“Existing screening tools are expensive and time intensive and there is an urgent need to increase cargo screening,” Szott explained.
“APOPO's rats are cost-efficient scent detection tools. They can easily access tight spaces like cargo in packed shipping containers, and can be lifted up high to screen the ventilation systems of sealed containers.”
Rat boot camp
The rats in the new study – Kirsty, Marty, Attenborough, Irwin, Betty, Teddy, Ivory, Ebony, Desmond, Thoreau, and Fossey – went through several rigorous stages of training.
They first learned to ‘nose poke’ a target scent for several seconds to earn a flavoured pellet. Then they were introduced to common scents that are used to mask wildlife in real-life trafficking operations, such as electric cables, coffee beans and washing powder.
The final step was retention training, where they were reintroduced to scents they’d not encountered for five and eight months, respectively. Despite the months of non-exposure, the rats showed perfect retention scores, suggesting that their cognitive retention performance resembles that of dogs.
By the end of the training, eight of the rats were able to identify four commonly smuggled wildlife species among 146 non-target substances.
Why now?
The statistics around the IWT – defined as the illegal capture, killing, or harvesting of animals and plants – have grown increasingly bleak in recent years. The World Wildlife Fund (WWF) estimates that it's currently the fourth biggest illegal trade in the world, worth over an estimated £15 billion annually.
They also estimate that around 55 African elephants are killed for their tusks every day, over 20,000 a year. They also saw a 9,000 per cent increase in rhino poaching in South Africa between 2007–2014.
Obviously, this is detrimental to the wildlife populations, but a 2019 study by the World Bank also estimated that the long-term global losses to ecosystems affected by IWT is around $1–2 trillion (£700 billion–1.5 trillion) per year.
Ratting on crime
The scientists involved in the new detection study have already identified the next steps of the HEROrat project: developing ways for the rats to work within ports that are likely hotspots for smuggled wildlife.
For this purpose, the rats will be outfitted with custom-made vests (that appear to be inspired by the iconic red Virgin Atlantic cabin crew uniforms). With their front paws, they will be able to pull a small ball attached to the chest of their vest, which emits a beeping sound. This way rats will be able to alert 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,” said co-author Dr Kate Webb.
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