Christmas Island’s Red Crab Migration Takes Over the Coastline

Christmas Island is currently hosting a fascinating natural phenomenon — the mass migration of tens of millions of red crabs.

Triggered by the first substantial rain of the wet season, adult red crabs leave their forest homes in the interior of the island, going on a journey toward the coast for mating and spawning.

Christmas Island, located 1,500km from the Australian mainland and 350km south of the Indonesian island of Java, is the location of this incredible migration.

The Christmas Island National Park staff has invested months in preparation for this event, setting up miles of temporary roadside barriers to guide the crabs to safety through underpasses and overpasses.

Additionally, traffic is diverted away from the migrating crabs to ensure their safe passage.

Derek Ball, the park manager, emphasized the significance of the red crab as the island’s keystone species, acknowledging the collaborative effort of the entire community in facilitating this natural phenomenon. In a statement, Ball highlighted the success in managing the red crab’s biggest threat, the invasive yellow crazy ant.

Over the years, crazy ants, first detected on the island in the 1920s, posed a significant threat to the red crab population by spraying them with potent formic acid. However, concerted efforts to combat the invasive species have yielded positive results. Scientists deployed a micro-wasp to prey on an insect that historically served as a food source for the crazy ants, leading to a decline in their numbers.

“This iconic natural phenomenon is not just incredible to see, but a fantastic success story of how we can work together to better protect our precious native species,” stated Tanya Plibersek, the federal environment minister. Thanks to the work of park rangers and community members, the red crab population on Christmas Island has more than doubled in the past five years, from 50 million to over 100 million.

This article by Trinity Sparke was first published by One Green Planet on 27 December 2023. Image Credit :alvarobueno/Shutterstock.

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