Red crabs Gecarcoidea natalis
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National Geographic's Great Migrations video
It takes the red crabs almost two months to make their way from the forest to the sea and back again. But that doesn't stop the island's human inhabitants needing to get from A to B. The result? The world's most careful drivers. Photo: wjusto21
The red crab is by far the most obvious of the 14 species of land crabs found on Christmas Island. Millions of these land crabs live over the island.
Where do they live?
Although most common in the moist environment of the rainforest, red crabs live in a variety of habitats including coastal shore terraces, and even domestic gardens. They dig burrows in soil or live in deep crevices in rock outcrops. For most of the year, a crab will settle in one place, living in their burrow.
Red crabs are diurnal (active during the day) and almost inactive at night despite lower temperatures and higher humidity. Sensitivity of crabs to moisture, combined with the seasonal climate on Christmas Island, create a distinct seasonal pattern of activity. Crabs retreat into the humid interior of their burrows during the dry season. They plug the burrow entrance with a loose wad of leaves to maintain a high humidity level, and effectively disappear from view for up to two to three months of the year.
What do they eat?
Red crabs diet consists mainly of fallen leaves, fruits, flowers and seedlings. They are not solely vegetarian however and will eat other dead crabs, birds, the introduced giant African snail and palatable human refuse if the opportunity presents itself.
Red crabs and forest ecology
Red crabs are important in the Christmas Island rainforest ecosystem. Their droppings scattered over the forest floor act as fertilizer. Their burrowing turns and aerates the soil and they are a major determinant of the unique structure and composition of the Christmas Island forest by their selective browsing on seeds and seedlings.
Red crab life cycle
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