Caribou Migration

Satellites and Caribou
The Why and How of Satellite Collaring Caribou

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Finding caribou locations using conventional VHF radio transmitters can be a problem because these animals live so far north. Extreme cold, blizzards and enduring darkness make locating the animals by plane difficult or impossible for much of the year. A satellite collar can send a signal in the dark of night and even in the middle of a blizzard.

Courtesy US Fish and Wildlife Service

There are two satellites that orbit the earth from North to South Pole 14 times each day. These satellites orbit the earth over 500 miles up (over 800 km). They scan for the collars signal and with the aid of computers onboard, locate the caribou within 1000 meters of accuracy. That's pretty good for 500 miles away!

From way up there in space the satellite can "see" a patch of the Earth about 3,000 miles (5,000 km) wide. At the speed that they travel, they have about10 to 14 minutes to register thecollar's signal before they go too far and lose it.

The collars on the Porcupine Caribou are programed to transmit a signal for 8 hours one day a week. At this rate, the collars should have battery power for 18 months. This seems to be a good program because collars are really expensive. One collar costs about $2700!

**Caribou wearing radio collar**

Do collars get in the way of the caribou? As a general rule, the collar total weight should be no more than 4% of the caribou's weight. What is the weight limit on a 200 pound caribou?

Do the Math!
To help scientists study the herd, they need to collar 8 caribou. About how much would it cost to buy them?

How Do You Collar a Caribou?
There are a couple of ways caribou are captured for collaring. Sometimes the animals are captured while they swim across rivers during migration. Biologists armed with ropes use canoes to get close to the caribou. Once roped they are slowly drawn to the canoe where a fresh collar is attached.

A second method involves a helicopter and a special tool called a net gun.Once the pilot locates the animal targeted for collaring, the shooter uses the net gun to propel a large net over the front half of the cow. The caribou is strong and requires a couple of people to get her under control. Her legs are tied to prevent because a caribou can kick really hard. Once they are tied the animal calms down and the collar can be put on. Scientists can also take measurements and blood samples.

Using a Net Gun to Capture a Caribou for Collaring