March of the red crabs: months of preparation for annual mass migration on Christmas Island

Temporary roadside barriers set up to channel tens of millions of crabs migrating to the coastline

The welcome mat has been rolled out for scores of red crabs as they make their annual coastal dash on Christmas Island.

Each year, the first substantial rain of the wet season triggers tens of millions of adult red crabs to leave their forest homes, in the interior of the island, and march towards the coast to mate and spawn.