As part of a five-year study of biodiversity in the Amazon, the World Wildlife Fund recently began using RFID transponders to track white-lipped peccaries, reports Wired magazine’s online hub.

According to the article, the tusked pig-like animals, which weigh 100 pounds or more, descend on natural salt and mineral deposits called collpas to chow down on clay that aids in digestion and supplements their mineral-deficient diet.

For the study, WWF researchers are tagging peccaries from different herds with RFID transponders. Four RFID readers in strategic points around the site passively register data on the tagged animals’ visits for WWF staff to download later.