On Christmas Island we have been busily preparing for the annual red crab migration. It’s a world-famous display of nature working in harmony - but we add a helping hand to ensure as many crabs as possible make it safely from the forest to the ocean to mate and spawn.
We’ve added five km of temporary fences to the 12 km of permanent fencing that funnels the crabs along the sides of roads and into the underground crossings. We’ve also cleared a year’s worth of leaves, dirt and debris from the tunnels so the crabs can move through them quickly and easily. It’s a mammoth job and we’ve had to work quickly.
It’s been very dry on the island for the last few months but two nights ago we finally had some decent rain. This got some of the crabs enthused enough to start making a dash towards the coast and try to make the November 28th spawning date. For others it wasn’t enough to coax them away from their burrows just yet.
The rain seems to have gone away again so it may be a false start. If we get some rain in a couple of weeks the crabs may begin moving slowly down to the coast for a 28 December spawning. It’s amazing that this tiny creature can execute this timed migration so finely!
While we wait we’re hand-baiting the yellow crazy ant supercolonies we can get to – which will help more crabs to get safely to the ocean.
As things begin to move we will make some visits to the community to let island residents know what the crabs are wanting to do - and what the residents can do to help. Many roads still see a lot of crabs on them so we ask drivers to slow down, and give them a demo of how to rake crabs out of the road. Some roads are closed or diverted so we try to make sure everyone knows this is going to happen and what alternative routes they can take.
Patience is the key now – all we can do is wait for this awe-inspiring phenomenon to begin.
Rob, Christmas Island National Park
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Behind-the-scenes of a natural phenomenon | Red crab migration begins on Christmas Island