After completing a trial of passive low-frequency and UHF RFID tags for cervid tracking, the Colorado Department of Agriculture has determined that active RFID tags may be the only way to gain the 100 percent read rate it seeks for cervid herds in the state. Cervid tracking is more rigorous in Colorado than in some other states because of a state mandate requiring ranchers to test dead elk and fallow deer for CWD, or chronic wasting disease. CWD is part of a group of ailments known as transmissible spongiform encephalopathies, which includes mad cow disease. If an animal decomposes before being tested, neither ranchers nor the state can determine if it died of the lethal and contagious disease.

In the most recent of two Colorado cervid pilots—using passive UHF RFID tags and interrogators (readers) made by Advanced ID Corp.—the state’s agriculture department was able to read 100 percent of the tags on one of the three herds tested, but considerably less on the other two, says Scott Leach, the department’s CWD field investigator. The first pilot, which took place in late 2004 and early 2005, involved low-frequency tags (134.2 kHz) and readers, with hardware supplied by Digital Angel, Allflex, Y-tex and Avid Identification Systems. The second, a nine-month trial held from March to December 2005, used Advanced ID’s UHF (915 MHz) tags and interrogators.