Swan Capture and Satellite Tracking
Swans are secretive and wary on their nesting grounds, and they all look pretty much the same when they are in a group, so individuals are usually hard to keep track of. But Dr. Scott Petrie at the Long Point Bird Observatory in Ontario is keeping track of some individuals that he marked with satellite transmitters. Dr. Petrie captures some swans by firing rocket nets over them in wetlands and in flooded fields. Once the birds are captured, they are weighed, measured, and banded. Dr. Petrie figures out what sex each bird is. Satellite transmitters eventually fall off, get damaged, or lose their battery charge. For 1999, Dr. Petrie decided to use neck collar-attached 30 g transmitters in hope that he would be able to track birds longer. Five birds were captured in March 1999 and tracked on their journey north.
According to Swan Satellite Tracking Website, "The way it works is quite remarkable. There are 3 satellites that continuously orbit the globe and detect the locations of transmitters. The satellites orbit at 850 km above the Earth?s surface and they can detect the presence of transmitters across a 5000 km path each time they pass. When the satellite detects the frequency from a particular transmitter, it picks it up from several locations as it passes. This information is translated into a latitude and a longitude, relayed to a ground station in the United States, and then directed to Dr. Petrie?s computer via e-mail within 3-4 hours of the satellite pass. The beauty of this technology is that no matter where the satellite-transmitter affixed swans go in the world, he will know where they are without leaving his office!"
Some people worry that transmitters bother birds, or make them less likely to survive. But there are cases where birds would have died without a radio or satellite transmitters.