In gangster movies, mob bosses worry that a “rat” will betray them. Now, criminal wildlife poachers might need to start fearing real rats.
Scientists have trained giant African rats to sniff out rhino horns, pangolin scales, elephant tusks and tropical hardwoods – all endangered species favored by smugglers.
With their low cost, ability to squeeze into tight spots, and remarkable knack for remembering and distinguishing between scents, these oversized rodents could give law enforcement a leg up in their struggle to catch illegal shipments of wildlife, the researchers reported at the end of October in Frontiers in Conservation Science.
“Existing screening tools are expensive and time intensive and there is an urgent need to increase cargo screening,” said Isabelle Szott, who helped lead the research as a scientist at APOPO, a Tanzania-based organization that has made headlines training rats the size of small housecats to detect odors from land mines and people infected with tuberculosis.
Wildlife trafficking is a globe-spanning criminal enterprise worth as much as $23 billion a year. It has helped drive precipitous declines in charismatic species such as African elephants, whose numbers fell by 30% between 2007 and 2014. Over the last decade, an estimated 11,000 rhinos were poached, chiefly for their horns.
These smuggling operations often escape detection because they blend into the flood of goods flowing across borders in the global economy. Inspectors at ports can screen just a fraction of all shipments with costly x-ray machines. Specially trained dogs can home in on the smells of some illegal animal parts, but a single dog costs up to $30,000 and typically must be accompanied by a skilled handler.That’s where Kirsty, Marty, Attenborough, Irwin, Betty, Teddy, Ivory, Ebony, Desmond, Thoreau, and Fossey all come in. Those are the names given to the African rats trained and tested by APOPO to see if their sensitive snouts could be harnessed to call attention to contraband wildlife.
The rats went through an exhaustive training process, in which they were exposed to smells from bits of rhino horn, elephant tusk, pangolin scales and East African blackwood, a slow-growing plant whose wood is prized for musical instruments and decorations. Small containers of each substance were placed behind a plastic panel that contained holes into which a rat could poke its snout. Other containers held pieces of innocuous materials often found around illegal shipments, including electrical cables, plastic hair wigs, coffee beans and washing detergent. Later, some contained a mix, to see if the animals could tease out illegal shipments hidden with other items.
When the rat held its snout inside the hole that led to one of the illegal items for a certain amount of time, it would automatically receive a small bit of food as a reward. At the end of their training, the rats had a 99% hit rate on rhino horn, 90% for elephant tusk, and more than 75% for pangolin and wood, the scientists reported.
“The rats also continued to detect the wildlife targets after not encountering that species for a long period,” said co-author Kate Webb of Duke University.
The next step is to come up with a system to turn these laboratory performances into something that will help alert inspectors at a port to an illegal shipment. The researchers said the goal is to develop a vest worn by the rats and equipped with a small ball attached to the chest. When the rat sniffs out a target, it can tug on the ball to trigger a beep.
It would add whole new meaning to the phrase: “Ratted out.”
Szott, et. al. “Ratting on wildlife crime: training African giant pouched rats to detect illegally trafficked wildlife.” Frontiers in Conservation Science. Oct. 29, 2024.
Image: ©APOPO
