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New Species Alert: Giant Tree-Dwelling Rat Identified

Uromys vika

Story at-a-glance -

  • A new species of giant rat named “Uromys vika” has been identified on Vangunu Island in the Solomons, a nation near Papua New Guinea
  • The giant rats are about the size of small opossums — 18 inches from their nose to the tip of their tail, weighing in at just over 2 pounds and live in tree canopies
  • Despite being a newly identified species, the rats are critically endangered; it’s hoped that raising awareness of their existence will increase protections of their dwindling habitat

By Dr. Karen Shaw Becker

It’s always exciting when a new species is identified, and the recently discovered giant rat named “Uromys vika” is no exception. The name is an homage to the local name for “rat” on Vangunu Island in the Solomons: vika. Mammalogist Tyrone Lavery, a post-doctoral researcher at The Field Museum in Chicago, and colleagues led a years-long search for the giant, opossum-sized rat, after a tip from the local people.

"When I first met with the people from Vangunu Island in the Solomons, they told me about a rat native to the island that they called vika, which lived in the trees," Lavery said in a news release. "I was excited because I had just started my Ph.D., and I'd read a lot of books about people who go on adventures and discover new species."1 Seven years later, the discovery was made. Because the rats live in tree canopies that can be 30 feet high, finding the rats proved to be a challenge.

While locals knew they existed, there was no actual proof of them until one was found in a felled tree in November 2015. Hikuna Judge, a conservation ranger, preserved the rat (which had unfortunately died in the fall) and sent it to Lavery who said, “I immediately knew it was something new.”2

The giant rats are about the size of small opossums — 18 inches from their nose to the tip of their tail, weighing in at just over 2 pounds. Little is known about the rats’ behavior, aside from their tree-top abodes, but they’re known to chew round holes into nuts to get to the meat, and may even consume coconuts in this manner. If the rats eat nuts and fruit in the treetops, it’s very possible they play an important role in dispersing seeds, helping the local ecosystem.

The Vangunu giant rat is only known to exist on the island, where logging has dwindled away much of the native rainforest. In the village of Zaira, near where Lavery first discovered the rats, the forests have been preserved to make way for ecotourism, and, The Smithsonian reported, the remaining lowland rainforest on Vangunu Island (only about 30 square miles are left) are largely in Zaira.3 Still, efforts will be needed to protect this important new species.

The Vangunu Giant Rat Is Already Critically Endangered

Despite only recently being described in the scientific literature,4 it’s expected to be categorized as critically endangered. Lavery explained that it’s near the tipping point when it comes to determining the rats’ future, for better or for worse:5

"It's getting to the stage for this rat that, if we hadn't discovered it now, it might never have gotten discovered. The area where it was found is one of the only places left with forest that hasn't been logged … It's really urgent for us to be able to document this rat and find additional support for the Zaira Conservation Area on Vangunu where the rat lives."

The critically endangered designation will be necessary, the researchers wrote in the Journal of Mammalogy, “due to its small distributional range, apparent low population densities, and rapid progress of commercial logging on Vangunu Island.”6 The story is reminiscent of Bramble Cay melomys, small rodents that once lived on an approximately 9-acre low-lying island, Bramble Cay, in Australia’s Great Barrier Reef.

Conservationists had spent months planning and gaining permissions for a captive-breeding program for the critically endangered rodents. Unfortunately, by the time the scientists arrived there to try to save the species, no signs of the rodents remained. Surveys of the melomys population were conducted in 2011 and March 2014, but neither detected any of the rodents.

Despite that scientists still believed they would find some survivors in August 2014, but they were sadly mistaken. In January 2017, the animals were officially declared extinct, a sad reminder of the fragility of life on Earth. Researchers remain hopeful that the Vangunu giant rats will experience a different fate, however, with increased awareness helping to bring increased protections to their habitat.

Protections Are Needed to Save the ‘Vika’

Lavery and his team are installing cameras to find more rats, stressing the importance of protecting the species — the first new species discovery in the Solomon Islands in more than 80 years.

In addition to playing an important ecological goal, Lavery said, “These animals are important parts of culture across Solomon Islands — people have songs about them, and even children's rhymes like our 'This little piggy went to market.'"7 As for how the rats first got to the island, it’s thought that their ancestors probably floated there on vegetation. Lavery’s work is truly the stuff that adventures are made of, but much more than that, proving the rats’ existence is a necessary first step toward their future conservation.

While giant rats may sound like a nightmare to some people, keep in mind that rats are intelligent creatures. The African giant pouched rat, a rodent native to Africa that’s about twice the size of a gerbil, has even been trained to detect buried land mines and tuberculosis in humans! The giant rats living on Vangunu, meanwhile, are actually very cute, with caramel-colored fur, wide back feet and curved claws, the latter of which makes them quite adept at maneuvering in their tree-top homes.