It’s their annual migration from the rainforest to the ocean to mate on Christmas Island, off the north west coast of Australia. “They” are the Red Crabs that live on the island, all 50 to 120 million of them. The male crabs get to the beach first to dig burrows. When the females arrive, the crabs mate in the burrows. [As is often the case with their human counterparts,] the males leave right after sex to make the long journey back into the island’s forests, leaving the females to drop their eggs into the ocean. It takes about 20 to 30 days for the tiny baby crabs to hatch, emerge from the sea and head back home towards the forest.
View the pictures at: abc.