How do reindeer and caribou migrate between tundra and taiga habitats?

Reindeer and caribou are the same species (Rangifer tarandus), with "caribou" being the term used for those in North America. These animals are well-known for their extensive annual migrations between the Arctic tundra and the boreal forests, also known as the taiga.123

The migration cycle is driven by the need to find food in environments with low productivity. The process generally follows this pattern:3

• Autumn/Early Winter: As winter approaches, herds migrate south from their summer ranges on the tundra to the forest-tundra or lichen woodlands. In these forested areas, they rely on high-carbohydrate lichens, often called reindeer moss, which they access by digging craters in the snow.31
• Late Winter: During the harshest part of the winter, they may move further into open forests, seek out sedge-rich lake margins, or travel to windswept, snow-free mountains.3
• Spring: In April and May, the herds aggregate and form long columns to migrate back north to the tundra for the summer.13