MONTGOMERY-Studies of wild animals usually involve methods of uniquely identifying individual animals. A variety of methods have been used over the years – some methods essentially innocuous while other methods permanently scar their subjects. With the advances in technology, many animals can be marked quickly, permanently, harmlessly and inexpensively.
Banding of birds may be the most familiar tagging or marking method used by wildlife 
researchers. An aluminum band with a unique letter and number code is placed on one of the legs of the bird. Recapture of the bird, dead or alive, gives the opportunity to report that band to a central clearinghouse, the Bird Banding Laboratory in Patuxent, Maryland. Other studies will additionally mark birds with colored bands, flags, or wing tags with alphanumeric codes that allow a report without the recapture of the bird.
Not all species can use the same tagging methods used for birds. Some species are too small, and many species are shy, secretive and have life habits that do not lend themselves to remote viewing.
One method of marking, usually involving a reptile, involves permanently scarring the animal. Toes of lizards are clipped off in a sequence that allows identification upon recapture. The edges of a turtle’s shell are notched sequentially to allow identification when in hand.
Much preferred is a method of permanently marking an animal so that it is not harmed, permanently scarred or burdened. Such a technology in wide use in both industry and wildlife research is radio-frequency identification (RFID). A type of RFID tag commonly used is called a passive integrated transponder, or PIT tag.
Modern RFID technology can trace its roots back to the 1970s. Its use has grown as the 
cost of implementation has greatly decreased. The most common method of RFID involves a microchip attached to an antenna. Another device, a reader, emitting radio frequency energy is passed over the microchip. This energy enables the microchip to send its stored information through the attached antennae from which the reader collects, interprets and displays or stores. This is an example of a “passive” RFID tag. These passive tags are very small and similar in size and shape to a grain of rice. Some tags now are as small as a grain of sand.
Some may equate RFID tags with barcodes seen on product labels, but RFID tags have distinct advantages. First, RFID tags can contain significantly more information than 
barcodes. RFID tags do not fade, smear or tear. Perhaps most importantly, these tags can be placed out of sight since they operate on radio waves that pass through most substances.
When used on animals, the tiny RFID tag is injected and inserted just under the skin of the animal where it harmlessly and permanently rests. Many people have their pets micro-chipped. If their pet is lost, a reader is passed over the chip, and the chip relays information about the pet’s owner. For wildlife research, just about any species can be micro-chipped allowing for reliable and essentially permanent identification of the animal studied.
Depending on the tagging setup, another advantage of this marking technology is the 
possibility of automated tracking. In one case, fish of an endangered species were tagged. By placing the antenna of the reader on the river bottom, the movements of the fish could be tracked automatically nonstop year-round.
RFID will continue to rise in use as the readers and tags continue to decrease in cost, and the technology allows for easier and more remote detection.
For more information, contact Roger Clay, Alabama Division of Wildlife and Freshwater Fisheries, 30571 Five Rivers Blvd., Spanish Fort, AL 36527.
MEDIA RELEASE/Roger Clay, Wildlife Biologist, Alabama Division of Wildlife and Freshwater Fisheries
