Mice eating rare birds on Marion Island were proposed to be exterminated from helicopters
On the island of Marion Island, located two thousand kilometers from Cape Town, brutal mice are devouring giant and very rare birds alive. Experts fear that they will completely exterminate them and demand that something be done. The South African authorities promise to help: they will send helicopters to the island to destroy rodents from the air.
What is Marion Island known for, how cats and mice got there, and how it ended
The uninhabited island of Marion Island is located in the Indian Ocean south of Africa. It is a cold and inhospitable place, with strong winds, average temperatures of less than five degrees Celsius, and vegetation typically found on the tundra. The island is difficult to approach from the sea, so it is surrounded by traces of numerous shipwrecks.
At one time, Marion Island was teeming with wildlife. Millions of penguins, petrels and many different albatross nested there, including almost a quarter of the world's population of wandering albatrosses – huge birds with a wingspan of up to three meters. The only mammals worthy of attention were fur seals.
No one knows for sure how and when exactly mice entered Marion Island. They were first spotted on the island in 1818
Most likely, the mice escaped from one of the sunken ships or escaped from the ship of seal hunters who regularly visited there. Without natural enemies, the rodents multiplied uncontrollably and soon populated the entire island.
By the mid-20th century, there was no way out of mice on Marion Island. Therefore, as soon as a weather station appeared on the island, its workers brought and released five cats. This was a mistake: after catching mice, feral cats switched to albatrosses and petrels. After 30 years, they exterminated at least 450 thousand birds every year. Due to their fault, one species of petrels completely disappeared from the island, and others became much less numerous.
People tried to correct their mistake, but it turned out to be very difficult. It took nearly 20 years to get rid of the 2,000 cats that lived on Marion Island by the mid-1970s.
Without cats, the mouse population grew even faster, and climate change allowed them to breed more often than before. Now there are at least a million of them on the island. But for some reason the absence of cats did not help the birds. Experts learned the reason for this only in the early 2000s.
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In 2003, scientists first noticed wounded birds on Marion Island. In 2009, experts found clouded albatross chicks that were practically scalped. The only animal that could cause such wounds was mice, but this still needed to be confirmed.
Installed cameras filmed mice attacking birds. Rodents came at night and ate into helpless chicks, which were several times larger than them. Albatrosses and petrels are able to fend for themselves, but only in cases where they are dealing with other birds. They do not know how to protect themselves from rodents.
The chicks watched helplessly as the mice devoured them alive, and did not even resist
After the first attack, the chicks remained wounded, but alive. However, the mice came again and again, continuing to bite into the open wounds. Sometimes one bird was surrounded by a whole brood of rodents – and then there was no salvation.
The same thing was observed on other islands, where, like on Marion Island, mice multiplied. In 2019, representatives of the British organization Royal Society for the Protection of Birds filmed mice attacking albatrosses on the volcanic Gough Island in the South Atlantic Ocean.
Footage from cameras installed in albatross nests shocked researchers. Dozens of mice attacked huge adult albatrosses, after which they ate their chicks alive.
How they propose to save rare albatrosses and why this is a very risky undertaking
Experts believe that without human intervention, mice are capable of destroying rare species of albatross. The situation is so dire that in order to save the birds they are proposing to exterminate mice from helicopters.
During the operation supposed use from four to six helicopters, from which up to 550 tons of toxic substances will be dropped onto the island. The poison is dangerous to rodents, but is relatively harmless to other species.
The helicopters will be brought by sea from South Africa, but this requires approval from the South African authorities and money. The fight against mice will cost at least 25 million dollars (2.31 billion rubles). South Africa, which administers Marion Island, is ready to compensate only part of this amount.
The difficulty also lies in destroying every last one of the mice. If even one pregnant female survives, all efforts will go down the drain.
This is exactly what happened on Gough Island, where they fought mice for three years in a row and spent nine million pounds sterling (a billion rubles) on it. In 2021, when the project was already completed, one of the camera traps left by the scientists photographed the surviving mouse.
Gough Island mouse eradication project manager Andrew Callender admits the footage broke his heart. “You need to understand that if there is one mouse, then there will be more of them,” explained he in an interview with BBC News. “And this means that the project never achieved its main goal.”
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