The first thing you can imagine thinking of Christmas Island, is a place with cold temperatures as Lapland, with expanses of ice and vast uninhabited areas. Characterized by long nights with the bitter cold of the Arctic, populated by very friendly and nice peoples, surrounded by deep forests populated by wild animals.
Christmas Island though little known, is home to one of the most spectacular and beautiful migratory phenomena on the planet.
Is situated in the Australian territory, in the Indian ocean in 2500 km north-west of the city of Perth and 360km south of Java. The territory is part of a nature reserve, and only 1500 people live there and it is home to many species of animals and plants. This small island has a high scientific value; since it seems that until the end of the XIX century was uninhabited, so the flora and fauna have evolved without any human intervention. The island is particularly famous for its populations of red crabs, a species of land that is endemic to the island; but most of their spectacular migration from the forest to the coast.
This happens every year during the breeding season. If you are in the island during migration (October/November), the first thing you notice is the cracking sound caused by the movment of the crabs; that cover in a sea of red across the forest floor, so thickly , which can be easily seen from the sky. At the beginning of the rainy season, more than 50 million red crabs begin the migration from the forest to the coast to breed. Migration is generally synchronized across the island. The males lead the first wave of migration that followed progressively by females.
Generally crabs take about eight days to reach the sea; although the rains and overcast conditions and humidity make their trip to the coast long and difficult. After mating, the females release eggs into small tunnels on the sea, where the young larvae develop in small crabs. After be stayed about a month in the sea, the young crabs accompanied by adults make their long trip home.
After reaching the hinterland, crabs disappear for the next three years; between rocky outcrops, the branches of fallen trees and debris on the forest floor. Human activities have led to an increase in the number of red crabs that die during the annual migration. Such as deforestation, which causes dehydration in crabs when they are forced to cross areas without forest cover. But above all the many thousands of adults and young are crushed by vehicles crossing the roads on the island.
To address the problem, the staff of the National Park of Christmas island temporarily closes some roads, and install protective barriers and bridges to simplify the passage of the crabs in areas at risk. Also local communities and schools, creating posters and flyers, aimed at ensuring the awareness and attention to this phenomenon that characterizes the island only for a couple of months a year.
In addition to humans, there is another cause that is decimating the population of red crabs is the yellow crazy ant. Anoplolepis gracilipes, so called because of the hectic pace and aimlessly in all directions, comes from Africa. Having conquered and damaged several islands in the Indian Ocean has landed on the island, killing thousands of red crabsbut olso small birds, small mammals and reptiles.I red crabs have become the most endangered species on this island because they gather in large number during migrations becoming an easy target for raiding ant crazy.
Each migration becomes a massacre, at least 60 million crabs were destroyed by the yellow crazy ant. The yellow crazy ants attacking a million columns of red crabs, spraying formic acid into the eyes of the crabs make them blind; then make it a massacre. The Australian government, under whose jurisdiction falls the island, has tried in every way to defend the island from the crazy ants, but the ants continued to extend the area occupied while the red crabs decrease in number. In 2005 fell to 40 million, more than halved in a few years. The secret of the success of this invasion is that this type of invasive ants are very united, have thousands of queens and form supercolonies of millions and millions of specimens.
Fortunately, the problem caused by the ants is being solved in the best way. To reduce the impact of crazy ants, and preserve the ecosystems of the park; and was made a major program of baiting since 2002. The first step was to conduct a comprehensive survey of the whole island, to locate exactly where they were the most substantial supercolonies of ants.
For several months the park staff has inspected the entire island, and found more than 900 sites covered 784 hectares. The result was a detailed map of supercolonies of ants. Later in September 2009, a helicopter was used to distribute the food comes out. This technique has proved very successful and has allowed to decrease the density of ants mad of 98%.