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Q. My school group is studying migration of birds, researching how to use a GPS to track birds. I am researching information for a debate on how using GPS could be harmful to birds. How do they do that and how do they put the GPS on the satellite. I also was wondering how they track birds now -- is it efficient and does it hurt the birds or cause them discomfort? — Waterloo Middle School student
A. First, let us help with some of the confusing words that come up when we talk about satellite tracking.

For instance, GPS stands for Global Positioning System. GPS is a group of two dozen satellites in orbit above and around Earth. Each GPS satellite transmits a signal down to Earth where it can be received by anyone with a GPS radio receiver. The GPS radio signals are used by the receiver to calculate exactly where that receiver is on the surface of Earth. Radio signals arriving on Earth from a satellite are not harmful to birds or us.

Birds and animals are tracked by scientists who attach very small, lightweight transmitters to them. Imagine building a very tiny GPS radio receiver combined with a very tiny radio transmitter and attaching them to something which moves around. The GPS receiver would receive signals from GPS satellites and calculate the moving object's location. That location information then would be turned over to the transmitter, which would send out a signal with that information. The signal would travel up into the sky to be received by a passing tracking satellite (not necessarily a GPS satellite). That tracking satellite would receive the signal with the location information and, from its very high point above Earth, relay it on to a station faraway on the ground. At the ground station, the scientists who were in charge of the tracking project would receive the information and place the location of the moving object on a map. As the object moved around over many hours and days, a track drawn on the scientists' map would move around.

That's how tracking works. You can track cars, trucks, planes, trains, human beings, animals, fish, or birds. In fact, you can track anything to which you can attach a tracking transmitter.

Does it hurt an animal or bird being tracked? Generally it does not. It is the responsibility of the scientist to make sure it does not. Of course, you can imagine that it might be inconvenient or even uncomfortable, but scientists who watch their experiments carefully believe animals and birds adapt to their new "jewelry" right away and pay no attention to it.

Learn more about tracking birds, animals and fish by satellite  »»

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