When the leaves start to change color in the fall, people go outside to admire nature’s beauty. This changing of the seasons is seen as something fun for most humans. For many members of the animal kingdom, however, changing weather patterns cause them to migrate▼ huge distances. They leave in search of warmer weather, more sources of food, better breeding grounds▼, and more. National Geographic presents a series about some of the planet’s most amazing migrations in Trials of the Wild. Sometimes it is not the distance of the migration, but rather the huge numbers of animals involved that impress us the most. In the episode, “Night of the Christmas Crab,” film crews travel to a remote island in the Indian Ocean, which is home to the Christmas Island red crab. Unlike most crabs, these ones spend most of their lives in the forest. Every October and November, they rush together across the island in the tens of millions, making their way to the ocean to breed▼. It is a sight that is almost impossible to describe—there are so many crabs crawling around that it looks like the ground is alive. Catch this sight and nature’s other great migrations in National Geographic’s Trials of the Wild.