The annual migration of this endemic species like the red crabs in Australia is considered one of the most fascinating events in the natural world.
True to their annual appointment around this time, the small Christmas Island, belonging to Australia, is literally covered by red crabs (Gecarcoidea natalis).
Millions of these animals begin their collective migration, moving from their shelters in the wooded areas of the island’s interior to reach the ocean.
It is a genuine natural spectacle starring this species, which is endemic to this island and arouses the admiration of all who witness it. The roads are completely invaded by these small crustaceans, and many of them, unfortunately, perish under the wheels of vehicles.
This happens despite the fact that authorities usually take measures to close traffic or facilitate the crabs’ movement under safe conditions.
During their migration, the red crabs on Christmas Island cross the terrain to reach the coast. Once there, they proceed to dig their nests, mate, and finally lay the eggs from which even more numerous offspring will emerge.
The island’s authorities have implemented a series of protocols for years aimed at preventing the death of these animals.
The roads, for example, have special infrastructures such as underground and elevated crossings. These are designed to help the crabs avoid crossing the road, while allowing cars to continue their circulation.
100 million red crabs on Christmas Island and 1,500 inhabitants
The small human population of the island, which is around 1,500 people, simplifies the management of this extraordinary natural phenomenon. According to figures provided by the Christmas Island National Park, its territory is home to approximately 50 million crabs. However, this estimate has been recently revised upwards, and their current number is around 100 million specimens.
This remarkable increase has been possible thanks to the control and eradication of the dangerous yellow crazy ant, which directly threatened the crabs and hindered the healthy development of their populations.
After reproducing, the female red crabs lay their eggs in the nests they have built near the coast. After a few weeks, usually around December or January, the hatching occurs: the young break the shell and head to the sea, where they will complete their first growth stage.
However, after spending a month in the ocean, the small crabs emerge from the water and begin the return journey to the forests in the island’s interior. There they will join the adult population to continue their growth.
This species, unique in the world, has faced various threats, the main one being the introduction of invasive exotic species on Christmas Island. One of these species was the African giant snail which, indirectly, attracted the yellow crazy ant.
This ant became a significant predator of the red crab. Fortunately, this ant species is being successfully controlled through ecological methods, which has enabled the recovery of the crab populations.
