Millions of red crabs have begun the long journey marking their annual migration to the coast of Christmas Island. The migration begins with the first rains of the wet season on Christmas Island, an Australian territory in the Indian Ocean. Each year, it takes months of preparation by Christmas Island National Park staff to set up miles of road barriers and signs to ensure that the crabs pass over specially constructed bridges. The speed of the migration depends on the phase of the moon, as red crabs always spawn before dawn on a falling high tide during the last quarter of the moon, according to Parks Australia. The crabs move in large numbers from their forest to the sea. Parks Australia expects spawning to occur toward the end of the month. Each female crab can release up to 100,000 eggs into the ocean. The resulting baby crabs are expected to return to shore a month later and return to the forest.