Porcupine Caribou Herd Satellite Collar Project is a cooperative project, between a number of wildlife agencies and boards, using satellite radio collars to document seasonal range use and migration patterns of the Porcupine Caribou herd in the northern Yukon, Alaska and North West Territories.
The herd ranges from Kaktovik, Alaska, to Aklavik, NWT, to Dawson City, Yukon. While most of this very large area is traveled by the herd, use of specific areas is not always predictable except during calving.
Satellite tracking overcomes some older location techniques. Previously, in order to find caribou wearing conventional radio collars, the scientists had to use airplanes to locate them. Unfortunately, flying a plane in the north often is held up by weather and darkness.
On the other hand, a satellite automatically picks up the signal from a radio collar even in the dark and through snow storms.
The satellite radio collars include a small transmitter which sends a signal to a satellite passing overhead. A computer aboard the satellite calculates the location of the caribou and sends the information to one of three ground stations.
By the way, such satellite collars and tags are useful with many different kinds of animals that travel long distances, such as Canada Geese which can travel up to 1,200 miles in one season, or with animals which live in harsh remote areas, such as polar bears on ice packs or whales in the ocean.
How much can it weigh?
The general rule for any satellite radio collar placed on an animal is that the device should not weigh more than four percent of the animals' body weight. For instance, if a caribou weighed 200 pounds, the collar should not weigh more than 8 pounds.
If the collar weighed more than four percent of the animal's body weight, it could start to interfere with the animals' natural behaviour and health. The satellite collars placed on animals in Porcupine Caribou herds weigh about four pounds.
How long do they wear the collars?
The collars on Porcupine Caribou transmit a signal for eight hours on one day a week. The collars are expected to transmit over eighteen months.
Here's an example of the timeline. In October 1997, eight collars were put on cow caribou while they were crossing the Porcupine River. In November, the researchers captured two more caribou using a net gun and put the satellite collars on them. They recaptured all of the caribou in March 1999 to take the collars off.
The ARGOS satellite system
The satellite system, known as ARGOS, is provided by France's Centre National d'Etudes Spatiales (CNES), the U.S. National Aeronautics & Space Administration (NASA), and the U.S. National Oceanic & Atmospheric Administration (NOAA).
ARGOS also has been used to monitor sea currents, snow stations, world weather, ships, weather balloons, river water flow, volcano activity, as well as movements of animals
Some other animals which have been tracked by satellite include polar bears, muskoxen, elephants, camels, turtles, sharks, whales, wolves, and birds such as swans and eagles.
There are two ARGOS satellites about 527 miles above the Earth. Both circle the planet from the North pole to the South pole fourteen times a day. They take 101 minutes to go completely around the Earth.
Each satellite sees an area of Earth more than 3,000 miles wide. However, since it is travelling so fast, it sees any one animal radio collar for only ten to fourteen minutes each time it passes overhead.
The satellite records the location of the radio signal it receives relative to itself then makes sure it knows where it is, using eleven beacons on earth. The satellite can locate an animal collar signal on the surface within about 3,000 feet. The animal information is sent by the satellite to one of three ground stations -- Fairbanks, Alaska, Wallops Island, Virginia, and Lannion, France.
SOURCES: Canadian Wildlife Service, YTG Renewable Resources, Government of the NWT, Porcupine Caribou Management Board, Alaska Dept. of Fish & Game, Centre National d'Etudes Spatiales, National Aeronautics & Space Administration, National Oceanic & Atmospheric Administration, and Space Satellite Handbook.
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