Giant coconut-eating rat found in Solomon Islands

Scientists have recorded a new species on a remote South Pacific island, but warn that habitat loss means it is already close to extinction.

For the Vangunu people of the Solomon Islands, the vika rat isn't a new discovery. They have always shared their forested island home with the giant-tree dwelling rats, which even features in nursery rhymes.

Schädelknochen der Riesen-Ratte

The skull of Uromys vika

Now, Uromys vika has also be described and classified by Western scientists - and immediately put on the list of critically endangered species. 

Tyrone Lavery, a biologist with the Field Museum in Chicago, heard locals talk of a giant rat that cracked coconuts open with its teeth, but searched for years without seeing it in the flesh.

"I started to question if it was really a new species or if people were just calling regular black rats 'vika,'" Lavery said.

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When a specimen eventually turned up, Lavery quickly realized it could only be the elusive rodent of local legend. "Looking at the features on its skull, I could rule out a bunch of species right away," he said.

"The new species is pretty spectacular," he added. About four times the size of a regular rat, the Field Museum can't confirm that it cracks open coconuts, but it does gnaw holes in them with its teeth.

The remote Solomon Islands archipelago is isolated, and over half the mammals there exist nowhere else on earth.

Nüsse, von Riesen-Ratten angenagt

Nuts gnawed by the vika

"Vika's ancestors probably rafted to the island on vegetation, and once they got there evolved into this wonderfully new species," Lavery said.

Living on just this one island, where its habitat is shrinking due to logging, Lavery said the vika could easily have become extinct without ever being scientifically recorded.

"It's getting to the stage for this rat, that if we hadn't discovered it now, it might never have gotten discovered," he said. "The area where it was found was one of the only places left with forest that hasn't been logged."

The scientist called for support for the Zaira Conservation Area on Vangunu, which is managed by local villagers.

Nature and Environment

The cunning culprit

Well into the 20th century, the brown rat was a frequent stowaway aboard ships. That's how it came to settle in South Georgia, a remote island in the southern Atlantic, along with house pets and reindeer brought over by whalers. The dogs and cats didn't survive the harsh Antarctic winters, and the last reindeer were relocated. But the rats thrived, multiplying to plague proportions.

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Easy pickings

South Georgia is home to birds found nowhere else in the world, like the South Georgia pintail duck (pictured), and the South Georgia pipit, the only song bird found in the Antarctic region. Because trees are scarce, birds build their nests on the ground. That means their eggs and chicks are easy prey for looting rats.

Nature and Environment

A plan is hatched

In 2011, scientists on the island decided to do something about the plague. Working in three phases - separated by two-year intervals - they laid rat poison out across the entire territory. Conveniently, glaciers form natural barriers, meaning rats can't easily migrate to repopulate areas where they have been eradicated.

Nature and Environment

Ghost town on ice

Logistics for the operation were masterminded from Grytviken, King Edward Point, one of the only settlements on the archipelago. Only 30 people live there during the Antarctic summer. They work mainly in the island administration, sometimes receiving cruise ships and overseeing the island's nature conservation programs.

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Head rat-hunter

British biologist Sarah Lurcock has been leading the rat eradication program with the South Georgia Heritage Trust from the very beginning. She also runs the museum in Grytviken, and every year receives thousands of cruise ship tourists eager to learn about the island's history and nature.

Nature and Environment

Aerial attack

The rat eradication team used three helicopters to distribute their cargo across remote parts of South Georgia. Often braving severe weather conditions - with storms, snow and ice - the conservationists threw rat bait from the choppers. Two helicopters broke down during the campaign.

Nature and Environment

Deadly meal

The rat bait only takes effect some time after it has been eaten. That's to give the rodents a chance to go back to their dens to die, and to prevent local birds like skuas, petrels and caracaras from feeding on the toxic carcasses. It's still unclear to what extent the poison could impact the island habitat itself.

Nature and Environment

Peanut butter bait

At the end of each phase, the scientists set up peanut-butter flavored wax bait to check if any of the rodents had survived. If the bait shows signs of being gnawed, clearly not all the rodents have been killed. But so far, the wax has remained untouched.

Nature and Environment

Canine inspectors

If the bait remains uneaten, that should signal a major success for the scientists. But to be sure, dogs were brought in from New Zealand to help scour the island for survivors. It's the final test of whether the operation has worked. Here's hoping the hounds will come up empty-muzzled.

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