Millions of bright red crabs have begun their yearly mating migration from the forest to the sea on Australia’s Christmas Island. The scarlet crabs are marching from the jungle toward the Indian Ocean, swarming roadways, parks, and residential neighborhoods, so they can mate in or near burrows by the water. Many roads are closed and specially-made crab bridges have been erected to allow the crabs to more safely cross the larger thoroughfares.
The Washington Post reports that according to the Australian government, some 50 million red crabs live on Christmas Island and Cocos (Keeling) Islands — the only places in the world where they can be found. The phenomenon happens each year and is determined by the phase of the moon, according to Parks Australia, which calls the mass migration “one of the most incredible natural processes on Earth.”