A Tale Of Two Alaska Caribou Herds

Caribou herds in Arctic Alaska tundra areas are on opposite trends, reports Yereth Rosen, @yjrosen.bsky.social, of @alaskabeacon.com: alaskabeacon.com/2025/01/20/c…

Alaska Beacon (@alaskabeacon.com) 2025-01-20T16:30:19.881Z

The Alaska Beacon has an intriguing report on two Alaska caribou herds, one that is on the upswing, and the other declining:

The Western Arctic Caribou Herd, once the biggest in Alaska, is faltering, having fallen from a high of 490,000 animals in 2003 to only 152,000 as of 2023. But to the east, the Porcupine Caribou Herdappears to be thriving, with an all-time high of 218,00 animals recorded at the last census. That makes it, rather than the Western Arctic herd, the state’s largest.

Why are the herds following opposite trends? An answer, Alaska scientists say, is found in what is growing on the ground – and the way the warming climate has changed those plants.

Woody shrubs and even trees are spreading rapidly over Arctic regions of Northwest Alaska, the area where the Western Arctic herd ranges, said Roman Dial, a professor at Alaska Pacific University. But that plant transformation, which scientists refer to as “shrubification,” has been much slower on the eastern side of Arctic Alaska, the range for the Porcupine Caribou Herd, he said.

For caribou, growth of woody plants like alders and willows means problems. Caribou depend on tundra plants like lichen and mosses; the shrubs and trees taking over the terrain are reducing the availability of that food favored by the animals.