Global Positioning System, or GPS, was developed by the U.S. military for defense purposes. Now open to civilians, this satellite network has revolutionized research in many fields.

In the Yukon, researchers have started using GPS collars to track grizzly bears in Kluane National Park. Biologists are now compiling the data from a seven-year study of grizzly bears in the park. They are trying to learn as much as possible about the bears while their environment is still relatively untouched.

They used conventional radio telemetry collars on dozens of animals, but they also experimented with two collars equipped with GPS. The receivers on these collars pick up signals from a system of 24 satellites in orbit around the earth. The receivers can be programmed to record the animal's location several times during the day.

This information is a goldmine for researchers. With radio telemetry, biologists only know the location of a collared animal when they fly over it, which usually happens once per week. They use a receiver on board the airplane to pick up signals from the animal.

The steady stream of information from a GPS collar gives a much more complete picture of the bear's habits. Park managers can use information on where the bears travel, and when, to help protect this species.

"GPS can help us determine really important movement corridors. We can track the trails and valleys in which the bears are moving and where they are feeding," says Kevin McLaughlin, a Kluane Park warden who worked on the bear study.

Using GPS collars also means that researchers don't have to fly as often to track the animals. This is a big advantage in a park like Kluane where there are few roads. In this remote area, flying is usually the only way to collect information on large mammals like grizzly bears.

But in this mountainous area, unsettled weather can ground planes for days at a time. Also, flying to remote areas of the park is expensive. Add these factors together, and the high cost of a GPS collars can seem less prohibitive.

They cost about $7500, compared to around $500 for a conventional radio telemetry collar. One type of GPS collar stores the information "on board" until the collar is retrieved from the animal. The other system uses a satellite uplink so that the information can be retrieved back at home base by computer.

So far the GPS collars have been used on three bears. The GPS collar with the satellite uplink was used to track a female grizzly that had destroyed a hiker's camp. The bear was relocated to a remote area, and the wardens tracked her with the help of the GPS collar.

When the grizzly returned to the original area, they were waiting for her. They shot her with a rubber bullet after she wandered into their camp, hoping to teach the bear to stay away from hikers and their camps. So far the plan seems to have worked, as the bear has not been involved in any other incidents.

Another GPS collar was used on a bear that was wandering out of the park and close to people's homes. The third one was placed on a female grizzly near Goatherd Mountain on the Alsek River, a remote area that is often used by rafters.

McLaughlin says that GPS collars could be used more in the future to keep track of problem bears. It could be a way to manage the bears without having to destroy them. But even a collar on a potential problem bear can transmit a huge amount of useful information for biologists.

With the GPS collars, the researchers have already learned that the home ranges of two female bears were much larger than they had predicted. One was more than double the area estimated with conventional means.

Rob McCann, the project biologist for the study, plans eventually to overlay information from the GPS collars onto a topographic map. This combination will show what areas the bears use the most, and what habitats are important for them.

But he says that GPS collars will never be the only tool for studying wildlife. "GPS can give information on things like home ranges and travel corridors. But if you want information on population dynamics, such as the size of litters, and how many cubs are surviving, you need to go out there and take a look."

One disadvantage of the collars is that the bears have to be handled more often. Conventional radio collars can be left on the animals for two to three years. The GPS collars transmit so much information that they drain batteries more quickly. These collars are put on in the spring and taken off in the fall.

Park managers and biologists plan to continue experimenting with the GPS collars, keeping in mind the plusses and minuses of this new technology. But as more visitors come to Kluane, and development around the park increases, the need for good information on grizzly bears will continue to be a concern.

For more information on grizzly bears in Kluane Park, contact the park's visitor reception center at (867) 634-7207.