Critters on the air: keeping track of who’s where
February 23, 2012 —
Since the 1950s, researchers have been using telemetry to study the movements of animals in the wild. One limitation back then was that only large animals, such as elk or bear, could be telemetered, because the technology of the day was vacuum tubes and relativity short-lived battery packs. But then came the age of the transistor, then the integrated circuit, and finally, hybrid chips containing millions of transistors. One desktop PC would have filled up an average town meeting hall in 1975 for a system of equivalent capability.
This technology has been utilized in our region with bald eagles. Along with the re-introduction of the bald eagle by many state wildlife agencies came much research focusing on movement and migration of eagles in the wild. Due to advances in circuit size reduction and battery technology, the average Platform Terminal Transmitter (PTT) used for satellite tracking of eagles is just 70 grams in weight and lasts three years or more.
One of the newest technologies being utilized is the use of Radio Frequency Identification (RFID) technology. Key fobs for building access use RFID. These are passive devices that require no power source and are powered solely by low-level energy generated by the reader. The key fob transmits its code to the reader and the reader sends the parsed code to a security controller, which might activate a door opening mechanism, for example.
RFID tags have been used on everything from bats to beavers in wildlife research; even tagged fish have been counted migrating up streams and other waterways. Cornell University has recently undertaken a method where an RFID reader is placed on a bird feeder to tally any tagged birds. The tag itself is 12 by 2 mm (about the size of a grain of rice), attached to a conventional leg band used for bird banding. Several feeders placed throughout the study area have tracked movements of individual birds, as they are likely to visit convenient food sources. Visit www.birds.cornell.edu/pfw/News/RFID.html.