Nature lovers each year flock to Christmas Island, Australia, around late November to witness a scarlet sea of tens of millions of red crabs migrating down from the forest to mate and spawn on the shoreline. Male red crabs set out on the journey first, triggered by the first rainfall of the wet season; they are soon followed by larger numbers of female red crabs. “World-renowned naturalist Sir David Attenborough described the red crab migration as ‘like a great scarlet curtain moving down the cliffs and rocks towards the sea’ and considered filming the spectacle as one of his 10 greatest TV moments,” said Bianca Priest, Christmas Island National Park acting manager. “Over the years, visitors have traveled from every corner of the world to witness this wildlife phenomenon.” Visitors hoping to take in the remarkable wave of red crabs may find some of the roadways blocked on their migration …