Satellite Collars

Home ENR Home GNWT Home Contact Us Links Search

Barren-ground Caribou
Satellite-collared Caribou

About Caribou Collaring

Since 1996, movements of barren-ground caribou cows have been tracked using satellite collars. Cows are collared during the winter and their movements are tracked by satellite throughout the year. The collars help us study seasonal range distribution, measure annual variations in rut and calving locations, and determine spring and fall migration routes.

March 2006 Collaring - All herds

Radio collars were also placed on caribou in the Inuvik and Sahtu regions (Cape Bathurst, Bluenose West and Bluenose East winter ranges) so that the caribou from the three herds can be photographed and counted when they collect together after calving. The caribou within each herd collect together in large aggregations as a response to mosquito and warble fly harassment. The aggregations are easy to find if they include radio or satellite-collared individuals and once found, the aggregations are photographed from an aircraft and the individual caribou counted.

Biologists in the Inuvik, Sahtu and North Slave regions provide weekly maps that show the movements of the satellite-collared caribou. Check these sites regularly for updates.

Caribou have a high fidelity to calving, summer and fall ranges, however their winter ranges are known to vary annually. Satellite-collars have complemented earlier knowledge that there is overlap in the winter ranges used by neighbouring herds in some years.

How the cows are collared

Biologists use a helicopter to locate caribou as they migrate onto the tundra. Once a group of caribou is located, a net is fired from the helicopter to capture one of the animals.

Within seven minutes of capture, the caribou is collared and released back into the herd. The caribou’s eyes are covered during the collaring to help reduce stress during handling. This procedure requires no drugs and places the animal in very little danger.

Each collar is programmed to fall off the animal at a specified time. Once dropped to the ground, a satellite signal is used to locate the collar so it can be reused in future studies.

SATELLITE MAPS
OF CARIBOU

Animation of collared
caribou 2001

Bathurst Herd

Archive weekly maps
Yearly movement maps 2001

Seasonal movement maps 2001

Cape Bathurst Herd
Archive weekly maps

Bluenose West Herd
Archive weekly maps

Bluenose East Herd

Archive weekly maps

Beverly and adjacent herds
Archive weekly maps

How caribou are tracked

The satellite collars turn on for six hours every five days. During this time, the transmitters send signals out into the atmosphere.

Four of the many satellites circling the Earth can pick up the signals from the collars. Each of these satellites passes within range of the collar transmitter at almost the same local time each day. If a collar is turned on while the satellite is sweeping that area for transmissions, the satellite picks up the signals and relays them to ground stations for processing. Our caribou data are relayed to one of the two ground stations in the United States.

The ground stations process the signals into longitude and latitude locations by measuring the Doppler shift on the transmitter signals. The Doppler effect is the change in frequency of the signal when a source of transmission (collar) and an observer (satellite) are in motion relative to each other. The ground station then emails the data to the caribou biologist.

During the six hours the collar is turned on, many location readings may be sent to the biologist from the ground station. The biologist plots maps according to the most accurate longitude and latitude signals sent from the collar. In ideal transmitting conditions, the accuracy of the coordinates can range from within 150 meters to up to 1000 meters from the actual location of the caribou.

The user agrees to the Terms of Use of the Government of the Northwest Territories
Site last updated Wednesday, February 13, 2008