Caribou Caribou migrations are one of the wonders of the subarctic and arctic realms. Traditionally, caribou have been among this region's chief food sources for humans, predators, and scavengers. The populations of some other animal species may even fluctuate with that of the caribou. Native peoples have depended on caribou for food, clothing, shelter, and tools, using the entire animal. Tundra is a mat of mostly prostrate vegetation that can grow where short summer s and other conditions preclude tree growth.
Tundra is underlain by permanently frozen ground called permafrost.
The ground surfaces of wet tundra and moist tundra thaw in the summer and stay waterlogged because permafrost prevents real drainage. In winter, when these are not available, they eat significant amounts of lichens called reindeer moss. Caribou can dig through snow to find food unless the crust is too hard, in which case they may suffer malnutrition and even starve. Besides predators, the chief antagonist of caribou in summer are the caribou warble fly, caribou nostril fly, black fly and mosquito. Caribou may even stop eating while trying to avoid the Arctic's summer hordes of biting insects.