Animal migration tracking

For years scientists have been tracking animals and the ways they migrate. One of the many goals of animal migration research has been to determine where the animals are going; however, researchers also want to know why they are going "there". Researchers not only look at the animals' migration but also what is between point a and point b to determine if a species is moving to new locations based on food density, a change in water temperature, and the animal's ability to adapt to these changes.

In the fall of 1803, American Naturalist John James Audubon wondered whether migrating birds returned to the same place each year. So he tied a string around the leg of a bird before it flew south. The following spring, Audubon saw the bird had indeed come back.

Scientists today still attach tags, such as metal bands, to track movement of animals. Metal bands require the re-capture of animals for the scientists to gather data; the data is thus limited to the animal's release and destination points.

Recent technologies have helped solve this problem. Some electronic tags give off repeating signals that are picked up by radio devices or satellites while other electronic tags could include archival tags (or data loggers). Scientists can track the locations and movement of the tagged animals without recapturing them using this RFID technology or satellites. These electronic tags can provide a great deal of data. However, they are more expensive than the low-tech tags that aren't electronic. Also, because of their size and weight, electronic tags may create drag on some animals, slowing them down.

Tracking an animal by radio telemetry involves two devices. Telemetry, in general, involves the use of a transmitter that is attached to an animal and sends out a signal in the form of radio waves, just as a radio station does. A scientist might place the transmitter around an animal's ankle, neck, wing, carapace, or dorsal fin. Alternatively, they may surgically implant it as internal radio transmitters have the advantage of remaining intact and functioning longer than traditional attachments, being protected from environmental variables and wear. A VHF receiver picks up the signal, just like a home radio picks up a station's signal. The receiver is usually in a truck, an ATV, or an airplane. To keep track of the signal, the scientist follows the animal using the receiver. This approach of using radio tracking can be used to track the animal manually but is also used when animals are equipped with other payloads. The receiver is used to home in on the animal to get the payload back.

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Wikipedia