A new type of border patrol agent could soon begin working at African ports, detecting illegal goods being smuggled across national borders. They are rats. And they wear tiny red vests.

Giant African rats were trained to identify pangolin scales, elephant ivory and other objects from endangered speciesthe researchers report on October 30 in Frontiers in conservation science. These animals could soon help deter international wildlife trade.

Wildlife traffickers “disrupt biodiversity on the ground by poaching specific species,” says Isabelle Szott, a behavioral ecologist who helped train rats in Morogoro, Tanzania, with APOPOa non-profit organization that deploys scent-detecting animals. “It’s very brutal.” Poachers could cut the horns of living rhinos or leave dead elephants rot on the forest floor (SN: 06/18/15).

Some ports employ dogs to detect illegal contraband goods, but African rats in their pockets (Cricetomys ansorgei) also have potential. The creatures have an incredible sense of smell. Additionally, they are agile and relatively inexpensive to maintain. Other rats trained by APOPO can detect landmines and detect tuberculosis in mucus samples (SN: 05/14/18).

Szott’s team taught 11 trainee rats how to differentiate between odors, including those from wildlife as well as other harmless odors. The laboratory was a giant box equipped with 10 small chambers into which researchers placed different samples. By rewarding the rats when they held their noses for three seconds above the target odor, the researchers taught the rats to signal and take snacks.

Rats learned to point out pangolin scales, rhino horn, elephant tusk and African blackwood, widely used in musical instruments. Ultimately, the eight rats who completed the project were able to distinguish the four odors from 146 other odors commonly used by smugglers to mask and hide their goods, such as cardboard, electrical cables and synthetic wigs.

Yet training rats in the lab to detect odors is only the beginning. Since then, trainees have ventured into simulated warehouses and some have even been deployed to real ports, says Szott, who now works for the Okeanos Foundation in Darmstadt, Germany.

As new wildlife detectives are trained, some members of the original cohort are now enjoying their golden years. Spoiled with fruits, vegetables and sun-dried fish, “they have a whole retirement colony at APOPO where they live out their days,” says Szott.