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Media Release
Greg Hunt MP
Parliamentary Secretary to the Minister for the Environment and Heritage

15 December 2005

Science saving rare crabs at Cristmas Island annual crab migration

Scientists and National Park Staff on Christmas Island have come up with a cost-effective way of saving hundreds of thousands of rare red crabs from their deadliest threat on their annual migration, Greg Hunt MP, Parliamentary Secretary with ministerial responsibility for Christmas Island National Park said today.

"The red crab, Gecarcoidea natalis, is found only on Christmas Island - and there are some 70 million of them," Mr Hunt said.

"At the beginning of every wet season the adult crabs begin a spectacular migration from the forest where they live down to the coast to breed. They release eggs into the sea and then return to the forest."

"The crabs have only one or two successful breeding years every decade and on a successful year, the baby crabs emerge from the sea after roughly 23 days and climb up the steep limestone cliffs and terraces to the forest.

"Tragically, during the migration, many thousands of adults and young crabs are crushed by vehicles while crossing roads that are in their path.

"Parks Australia Christmas Island scientists identified places where crabs cross in high numbers and built 'crab crossings'. The crab crossings are like a cattle grid - a concrete tunnel under the road with a grid in the road surface that admits light so the crabs will enter. Plastic fencing along the roadside funnels the crabs into the tunnels and stops them crossing the road," Mr Hunt said.

"This year Parks Australia park rangers have devised temporary 'crab bridges' to give the crabs safe passage over roads instead of under the roads to try and limit the contact the crabs have with underground infrastructure.

"This very effective solution has proved inexpensive with a total cost of $19,241.00 and has also been very popular with the local community," Mr Hunt said.

Mr Hunt said the crab crossings were needed because the park was losing around 300,000 crabs every year through changed traffic patterns.

"The crab population could not sustain such a huge loss just as we had begun rehabilitating the red crab population after the invasion of yellow crazy ants," Mr Hunt said.

"I congratulate Parks Australia Christmas Island staff on a achieving a great conservation outcome," Mr Hunt said.

Christmas Island's rare red crabs are extremely important to the island's rich biodiversity. They are a keystone species in the forest ecology, influencing the structure and function of the rainforest by selectively consuming seeds and seedlings, cleaning up leaf litter, turning over the soil, and fertilising it with their droppings.

Media contact:
Kristy McSweeney (Mr Hunt's office) 0415 740 722 - 02 6277 2276
Christmas Island (15-19 December) 08 9164 8055 ( Images are available)

Commonwealth of Australia