The impressive red crab migration has started on Christmas Island Roads, bridges, gardens invaded by swarms of thousands of crabs on the march. The scene looks like it came straight out of a science fiction movie. For Christmas Island, however, it is not unusual. It even occurs every year in this Australian territory located in the Indian Ocean at some 254 kilometers offshore of the coasts of Java.
This island is indeed famous for its red crabs of the species Gecarcoidea natalis which is endemic. It is estimated that the population is not less than millions of individuals who embark on a spectacular migration each year. The phenomenon generally starts at the beginning of the rainy season, in October or November.
On this occasion, the crustaceans that spend most of their time in the forest move by the thousands in order to reach the ocean before reproducing and laying their eggs. And all roads are good to reach the coast. For several days, crabs invade the streets and roads of Christmas Island, including in residential areas.
This year, the invasion started around the 1st November as evidenced by the photos and videos posted by Parks Australia, the institution that manages Australia’s six national parks including Christmas Island.
– Parks Australia (@Parks_Australia) November 9, 2020 ” With the red crab migration in full swing on Christmas Island, crabs are everywhere, including at the door of an office building! , “the institution wrote in another tweet showing several specimens stacked in front of an entrance. If the inhabitants are used to this mass migration, it requires a little organization.
For days, the authorities must indeed regulate traffic and close roads in order to be able to let the crabs move around safely. Temporary barriers and warning signs must also be installed in certain places and it is not uncommon for residents to find themselves stranded in their homes because of the phenomenon.
You’ve asked 📣, so we’re delivering. Please enjoy this footage of #redcrabs on the #crabbridge & around 🎅 Christmas Island 🦀🌉. One might even say it’s a … #crabrave 🥳 (we also have a very fun collaboration in the pipeline 😉).
📹 Credit: Chris Bray Photography pic.twitter.com / 1x2roQCnLj
– Parks Australia (@Parks_Australia) November 4, 2021 ” On Sunday, residents of Drumsite on Christmas Island were unable to leave their neighborhood because of the large number of crabs crossing the roads , ”Parks Australia confirmed in another tweet. The sight of thousands of crabs crossing the island is nevertheless a popular attraction that attracts many tourists every year.
Planned egg laying for the 28 – 29 November It usually takes at least a week for the shellfish to reach their target. As migration also depends on the phases of the moon, specialists believe that this year spawning should take place around 23 and 29 November. The eggs will thus be released into the ocean at high tide between the last quarter and the new moon.
Once mating is complete, the males return to the forest while females stay a few more weeks to incubate their eggs before releasing them. It is then up to them to make the return journey while the larvae begin their development. The young crabs will not come out for several weeks to reach the mainland.
The species G. natalis normally has few natural predators and competitors on Christmas Island. The population is however threatened by the crazy yellow ant ( Anoplolepis gracilipes), an invasive species accidentally introduced into the territory. According to a study published in 1951, the insect had already killed ten to fifteen million crabs in previous years.
D ‘where the importance of seeing these millions of crabs continue to spring up every year and to facilitate their journey to the ocean. ” They call it the best time of the year … and we’re not talking about the countdown to Christmas. It’s the crab migration season of the Island National Park. Christmas! “, rejoiced Parks Australia on Twitter.
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