On February 9, Blixen was just southwest of Aklavik, Cupid was almost due east of Old Crow, and Vixen was hanging out further south, near the Dempster Highway.

No, we're not talking about Santa's reindeer in the off-season. Blixen, Cupid and Vixen are three caribou cows, part of the Porcupine Caribou Herd, which ranges from the western Northwest Territories across the Yukon to the Alaska North Slope.

We know where they were on February 9 because they and seven other cows in the herd are wearing special collars that transmit their locations to satellites high above the earth. The Satellite Collar Project is a co-operative effort by a number of wildlife agencies and boards.

"The cows will wear their satellite collars for a year and a half," says Dorothy Cooley, a Yukon government biologist.

The information collected as they wander back and forth across their range will help scientists understand the Porcupine Caribou Herd's migration pattern and seasonal use of its habitat.

It will also help non-scientists learn more about the caribou. While the animals are roaming hundreds of kilometres across the northern Yukon, people from around the world can follow them on the Internet.

The Internet site provides weekly updates on the animals' movements, as well as information about how the collars and satellites work, why they are being used, and how to put a collar on an unco-operative caribou.

How do you, in fact, collar a caribou?

Well, eight of the caribou were collared in October 1997 while crossing the Porcupine River about 60 kilometres upstream from Old Crow. A capture crew in a boat would come up behind the swimming animals, pick out a likely cow, and catch it by the antlers with a long rope, guiding it alongside the boat. One person would hold the antlers while a second person put on the satellite collar. The whole procedure, for each cow, took only two to three minutes, and the puzzled animal was released to complete its river crossing.

"It wasn't as easy as it sounds because caribou are strong swimmers and can outmaneuver a boat," says Martin Kienzler, a Yukon government technician who took part in the capture.

In November, the remaining two collars were fitted on caribou caught by net guns, shot from helicopters. The net is shot over the front half of the chosen caribou, trapping its antlers and front feet and slowing the animal down so that it can be restrained. The feet are tied long enough to allow the collar to be put on and any other procedures to be completed. Then, the caribou is sent on its way.

The collared caribou are unwitting participants in a very high-tech study. Their collars are programmed to transmit a signal for eight hours, one day a week. The signals are picked up by two satellites circling Earth, from the North Pole to the South Pole, at an altitude of about 850 kilometres.

With the help of 11 beacons on Earth, the satellite can determine the location of the signal to within a thousand metres or better. That information is then sent to one of three ground stations in Alaska, Virginia, and France and forwarded to the Yukon by e-mail.

Tracking the caribou by satellite has advantages over the more traditional method of picking up radio-collar signals by aircraft. Flying is expensive in the north and frequently hindered by weather and darkness, whereas satellites operate 24 hours a day and can detect the collars' signals even in the dark or in a snow storm.

In March 1999, after two winters and a summer, the caribou will be recaptured and the collars removed. By then, the scientists tracking them will have a good record of the movements of the herd through the seasons and the use they make of their huge range.

And non-scientists who follow the travels of Blixen, Cupid, Vixen and the rest of the Porcupine Caribou Herd on the Internet will have a greater understanding of the lives of these remarkable animals.

For more information about the Satellite Collar Project, check the World Wide Web site, http://www.taiga.net/satellite/, or contact the Canadian Wildlife Service, Environment Canada, Whitehorse.