Carrying a Caribou's GPS Collar Out of the Arctic Wilderness

Denali backcountry ranger Taylor Bracher holds a caribou GPS collar she retrieved, north of the Continental Divide in Gates of the Arctic National Park and Preserve. NPS/Josh Spice.

Treasure in the wilderness

At Gates of the Arctic National Park and Preserve in Alaska, biologists fit GPS collars on caribou and other animals — about 350 since 2009. The collars send migration routes and seasonal movements by satellite, and show where to fly photo-census counts to estimate herd size. But a collar stores far more than it transmits.

When a collared animal dies in wilderness, rangers retrieve the collar on foot, avoiding mechanized travel. In July 2021, ranger Taylor Bracher found one high in a drainage north of the Continental Divide, and she and Gates of the Arctic ranger and photographer Josh Spice carried it five days through the Brooks Range to return it to the biologists who fitted it.

What the collar can tell

The stored data raise new questions. Wildlife biologist Kyle Joly wanted to know: did this caribou have a calf? Movement data can reveal calving and much else.

Why it matters to people

The herd's response to a changing climate could upend Alaska Native subsistence life, in which harvesting caribou at certain seasons remains vital.

• Fewer caribou migrate south. In the past, 80 percent or more of collared caribou went south for winter; in recent years, as few as 6 percent have.
• Later migrations spoil the hunt. Rural communities hunt fat bulls in the fall for winter food. When caribou migrate later, the bulls are often already in rut, and their meat is considered inedible.
• Farther to travel. The less predictable the migrations, the farther hunters must go from remote villages — and the harder it is to put up enough caribou for winter.

Each collar fitted and returned adds a piece to what Spice calls a puzzle without edge pieces.

Sources

Based on Josh Spice, "A Wilderness Treasure Hunt Unlocks Caribou Secrets," Park Science (Winter 2021), National Park Service; a work of the United States government in the public domain. Photograph: NPS/Josh Spice.