https://www.wired.com/gadgets/miscellaneous/news/2007/06/rfid_pigs
https://www.wired.com/gadgets/miscellaneous/news/2007/06/rfid_pigs
"Every few days, peccaries 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. (...) "In the past, wildlife researchers were limited to costlier, labor-intensive means of tracking wildlife, such as very-high-frequency or GPS collars. But cost and convenience are making RFID tags an attractive alternative for some types of field studies. "VHF costs at least $300 per animal, and GPS systems cost about $3,000 each," says Powell. "Ear tags are a few cents a piece, so you can put out hundreds of them."...
