The annual migration of millions of red crabs has commenced on Christmas Island, with tens of millions of the crustaceans embarking on their journey from forest burrows to the ocean to breed. This spectacular natural event, ignited by the start of the summer rains, transforms the island’s landscape into a moving red carpet as the crabs make their way across roads and gardens.
The migration involves up to 100 million of the estimated 200 million endemic red crabs, known scientifically as Gecarcoidea natalis, residing on the tiny Australian territory in the Indian Ocean. Triggered by recent rainfall, the crabs begin their slow march, primarily during the cooler hours of early morning and late afternoon to avoid the midday heat. Their path is often obstructed by human infrastructure, leading to unique interactions with the local community.
Christmas Island’s approximately 1,200 residents actively assist the crabs in their journey, using garden rakes and leaf blowers to clear them from roads and prevent casualties from vehicles. Special crab bridges have been installed in key areas to provide safe passage over obstacles, and local radio stations broadcast updates on the crabs’ movements to help residents navigate the invasion. Despite the inconvenience, many islanders view the event as a privilege and a unique aspect of life on Christmas Island.
The crabs’ behavior is indiscriminate; they will traverse any terrain in their path, including entering homes if doors are left open. Alexia Jankowski, acting manager of Christmas Island National Park, noted that the crabs’ determination means they must be manually moved from driveways and pathways to avoid harm. This human intervention is crucial for minimizing the impact of urban development on the natural migration.
The migration will peak with a major spawning event expected around November 14 or 15, during the last quarter of the moon. Male crabs prepare burrows on the shoreline where females spend about two weeks laying and incubating eggs. At high tide, the females release their spawn into the ocean, beginning the next phase of the lifecycle.
After spawning, the eggs hatch into tiny larvae that drift on ocean currents for approximately a month before returning to Christmas Island as juvenile crabs. Parks Australia staff then use leaf blowers to gently guide these small crabs, which are only about half the size of a fingernail, off roads to protect them from vehicles, as raking could crush them.
This annual phenomenon is one of the most remarkable wildlife spectacles globally, emphasizing the island’s rich biodiversity and the importance of conservation. The successful migration and spawning are vital for sustaining the crab population, with this year’s event potentially being one of the largest in recent memory, highlighting the resilience of nature amidst environmental changes.