Alaska’s tundra grazer
Caribou are the North American form of the reindeer, built for open, wind-scoured tundra rather than forest cover. In Alaska, records run almost entirely through the warmer months. They rise sharply in May, peak in July, then drop off fast once the short arctic summer ends. That pattern likely reflects both when caribou concentrate on accessible ground and when observers are out in the field, not a true year-round activity level.
A specialist diet of arctic plants
The plants recorded in its diet read like a tundra plant list: purple saxifrage, polar willow, black crowberry, Labrador tea, and creeping snowberry among them. These are tough, low-growing, cold-adapted plants that support little else at this scale. Caribou are one of the few large mammals equipped to live on them through an entire arctic year.
Predators at every stage of life
Caribou face pressure from gray wolves, brown bears, and polar bears at the northern edge of their range. Mountain lions take them farther south, where the two overlap. Calves are especially vulnerable in the weeks after birth, when they can’t yet outrun a chasing predator. That’s part of why calving is timed so tightly to the brief window of good tundra forage.
One calf, timed to a short window
Females reach breeding age at under two years old, males slightly later, and pregnancy runs close to eight months. Nearly every birth produces a single calf rather than twins, and a cow typically calves once a year. Wild caribou can live past 20. That’s a long lifespan for an animal that spends its whole life exposed on open tundra, with no forest cover to retreat into.
Conservation
The IUCN lists caribou as Vulnerable, a step down from the healthier status many herds held in past decades. Alaska’s herds still range widely, but caribou worldwide face pressure from a warming Arctic, industrial development crossing traditional migration routes, and shifting predator numbers that follow both.
