Radio telemetry runs on the same basic principles as the radio you listen to every day. A small portable transmitter (radio station) emits radio waves, which are picked up by a receiver through an antenna. Instead of transmitting the top forties or local rap stations, the wildlife transmitters emit beeps. Each animal is given a separate frequency (radio station number). Just like you can dial between stations, researchers can dial between animals. Why can't you pick up these beeps on your radio? The frequencies (radio station numbers) used by researchers are higher than can be received by your radio.
Using radio collars and telemetry equipment to follow or locate wildlife is not a new technique. Over the years, many species of wildlife have been studied using radio tracking devices. What is changing is the improvement in equipment. Early transmitters were large and bulky. Only large animals such as bear, elk, and moose could easily wear these collars.
Today, transmitters small enough to fit on the backs of songbirds or be clipped to the wings of butterflies are now being used to identify habitat use and gather information on migratory routes. Collars can even give signals that tell when an animal has died. This is important and allows biologists to quickly get to a site when the reason for the animal's death is important. Collar signals are now strong enough to be picked up by satellites. Researchers can program data collection based on an hourly, daily, or weekly movements.
In Michigan, radio telemetry has been used to monitor bear, moose and wolves to gain more information on habitat type and food preferences and even to locate denning sites. Small, temporary transmitters were glued onto a tail feather of young osprey released in southern Michigan, making it easier for osprey attendants to locate and identify the young as they fledged. DNR researchers have used satellites to track collared Canada geese up to 2500 miles during their north-ward post-breeding "molt-migration."