In order to get animal locations with conventional collars, we have to find them with airplanes. Flying in the north can often be held up by weather and darkness.
A satellite can automatically pick up the signal from a collar in the dark and even through snow storms. The collars consist of a special transmitter which sends a signal to a passing satellite. A computer on board the satellite calculates the location of the caribou and sends the information to one of 3 ground stations.

Satellite collars are also useful with animals which travel long distances (like Canada Geese which can travel up to 1,200 miles in one season), or with animals which live in harsh or remote areas (like polar bears on pack ice or whales at sea). To learn about other animals that are being studied using satellite radio collar technology, click here.

The general rule for any collar put on an animal is that it shouldn't weigh over 4% of the animals' body weight. For example, if a caribou weighs 200 pounds, the collar shouldn't weigh more than 8 pounds. If the collar weighs more than 4% of the animal's body weight, it may start to interfere with the animals' natural behaviour and health. Satellite collars on Porcupine Caribou Herd animals weigh about 4 pounds.

The collars on Porcupine Caribou are programmed to transmit a signal for 8 hours, one day a week. The collars should transmit for 18 months. Between the 2nd and 4th of October, 1997, 8 of the collars were put on cow caribou while they were crossing the Porcupine River. On the 18th of November, we captured caribou using a net gun and put the remaining 2 satellite collars on. Click here to learn more about how caribou are captured.