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New species of giant rat discovered in crater of volcano in Papua New Guinea

Bosavi giant woolly rat by Kristofer Helgen

Photo: Bosavi woolly rat (Photo by Kristofer Helgen)

A Smithsonian Institution biologist, working with the Natural History Unit of the British Broadcasting Corp., has discovered a new species of giant rat on a film-making expedition to a remote rainforest in New Guinea.

The discovery was made in the crater of an extinct volcano named Mount Bosavi in Papua New Guinea’s Southern Highlands province. This gigantic volcano’s circular crater is 2.5 miles wide and rimmed with walls nearly one-half a mile high, trapping the creatures inside a “lost world” of mountain rainforests probably very rarely visited by humans.


Photo: BBC wildlife cameraman Gordon Buchanan with the Bosavi woolly rat (BBC/Jonny Keeling)

Kristofer Helgen, curator of mammals at the Smithsonian’s National Museum of Natural History in Washington, D.C., and Muse Opiang, a biologist with the Papua New Guinea Institute of Biological Research, were first on the scene when the rat was found by a tracker from the Kasua tribe that lives outside the crater.

Weighing in at nearly 3.5 pounds, and measuring 32 inches from nose to tail, the Bosavi woolly rat is one of the biggest rats in the world. Most surprising of all, the rat was completely tame, a sign that animals in the isolated crater were unfamiliar with humans. “It is a true rat, closely related to the rats and mice most of us are familiar with, but so much bigger,” Helgen says.

Mt Bosavi by Kristofer Helgen

Photo: Mount Bosavi (Photo by Kristofer Helgen)

The gigantic rat is silvery gray, with thick woolly fur. It has a vegetarian diet of leaves and roots, and probably builds underground nests beneath rocks and tree roots. A member of the genus Mallomys, it has yet to receive its formal scientific name.

The discovery came in the middle of the night after days of searching in the crater’s chilly mountain rainforests, often in the pouring rain. “Our hearts were in our throats,” Helgen says, “it was an unbelievably exciting moment. It was all the more incredible that the BBC was there to film it.”

“As biologists, we spend plenty of cold, muddy nights in the rain”, Opiang says, “but rarely can we expect to be rewarded like this!”

Bosavi silky cuscus with biologist Muse Opiang by Kristofer Helgen

Photo: Biologist Muse Opiang holds a Bosavi silky cuscus (Photo by Kristofer Helgen)

New Guinea is famous for its diversity of rodents. More than 70 species of rats and mice (the rodent family Muridae) can be found on the tropical island, several of which have been named as new species in the past by Helgen.

It is currently estimated that along with the new species of giant rat, the expedition found approximately 16 species of frogs, one species of gecko, three species of fish, and at least 20 species of insects and spiders. Also on the list is an animal Helgen calls the Bosavi silky cuscus, which may be a new subspecies of tree-living marsupial. The animal—which looks like a small bear—is a marsupial that feeds on fruits and leaves. Weighing in at 5 pounds, it has dense silky fur adapted for a mountain environment. “Finding an animal like this for the first time in the 21st century is certainly cause for celebration” Opiang says.

Rainforest habitats in Mt Bosavi’s crater are currently pristine but extensive logging operations can be found just a few miles to the south. “Discoveries like this should remind us how much of the world is still left to explore,” Helgen explains, “and also how much stands to be lost when any rainforest is threatened.”


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  • mathew

    Where could one acquire one of these giant rats

  • HEY BRO!!!!!!!!!!!!!!!

    I researched this topic in 4th grade, I am in 6th grade now.  It was very interesting to learn about.  I am researching Papua New Guinea as a world fair project and using some of these animals as part of my project.  I have 2 or 3 weeks left of school and am super excited to present my project and gather more information on this entirely different place than kansas.  I AM EXCITED BRO!!!!!!!!!!!!!!!

  • So, tree rings correlate with global temperature, I read that everywhere. What if that is untrue though?? I read this book this week,, that clearly shows this supposed link to be unfounded. This changes everything, right? If this is the case, what implications does it have for the argument supporting global warming? I think this could be a very important realisation. What do you think?

  • It appears that you have put loads of hard work into this post and I want even more of those on the net now. I seriously got a kick from the post. I do not obviously have much to voice responding, I just wished to remark to your wonderful work.

  • Great post – and nifty domain by the way!

  • allie

    hi there we are six grade studens from monson M.A. we have been researching on this topic if you have any information we could add to make are project cool and interesting we would love it thank u sooooo much. bye the way awsome pics.

    6th grade volcanologist

  • We are going to be running ecoadventure trips to this incredible place as a personal request from the local tribespeople surrounding Mount Bosavi. This is due to the fact that they are under pressure for money ever since the government in PNG proposed that all children must be educated through proper schooling which is quite expensive. These remote tribespeople are subsistence farmers and have no way to pay for schooling, boarding and transport of children to schools in larger communities, so they are desparate in their need for money. Logging companies and oil companies are taking advantage of this weakness and have already choppered into the area to convince the people to sell their land rights for logging, for a good amount of money (but only a tiny fraction of what the wood will sell for on the foreign market). The community is divided and if something doesn’t happen soon to counter the loggers, this unique and absolutely incredible area (and all the wildlife that relies on this fragile balance) will disappear for ever. So, as an alternative to logging for money, we are the only company that will take people into this area, staying at the BBC base camps and visiting the amazing people and elusive animals that inhibit this area. A schooling bank account has already been setup now, for profits to go to paying for the education fee’s of the children in the villages we are working directly with and you can donate directly to this account or better yet, come with us on a trip of a lifetime! or (on the latter website, under trip photos button, see a slideshow from the most recent trip after the BBC shoot “Lost Land of the Volcano”)

  • Wendy Talene

    I lived in Papua New Guinea in the Southern Highlands Province until I was 18 years old. The Folopa people of Mount Tawa know of a spider with nine legs in that area. I wonder if any of these scientists finally found it and documented it. I believe it is in the wolf spider family, brown and fuzzy, about 4 inches spread out and lives in the dirt rather than making a web. It seems to have a seasonal population growth pattern. Anyone document it yet?
    Also, there are a great many giant rats in the village I grew up in so it doesn’t surprise me that they are also nearby in the crater.

  • JK Brown

    The actual discovery of a giant rat in PNG isn’t the reason for the scientific community’s excitement. The excitement is centered around the fact that this rat has been ‘cut-off’ from the outside world and has lived for thousands of generations in isolation within the Bosavi crater, cut off from the other giant rat’s that inhibit the jungles of PNG. The Scientists were excited that this species, like those of Galapagos Island creatures, may be completely new to science because of genetic variation within a limited genepool. A very amazing and unique thing to find these days, is an area of bio-isolation where the critters have no chance of interbreeding with an outside source of fresh genetic material, so the species that remain are very adapted to their narrow realm of conditions…..VERY AWESOME TO SEE FIRSTHAND IN THIS AGE WHERE WE ARE OFTEN TOLD THERE IS LITTLE LEFT TO DISCOVER. Yay!

  • I have a picture of giant rats in Papua New Guinea taken by my father Greg Neilsen who was a Patrol Officer up in that region in the 1930 era, they were being studied by a chap from England. I can photograph and send you proof. So he discovered these 3 foot rats years and years ago.

  • john naranjo

    omg i like i luv dis animal. its so awsome looking i wish i had a pet for it cause my mom always says i can get a rat and i would be really interested in buying one of these. please send me a message back if i can buy one thank you from animal lover xx123957

  • More reason for us to save our rain forrest. So many valuable medicines, plant and animal life destroyed before they are every discovered. Good work!

  • Misty


  • mleffel

    You never know what will pop up next!

  • Interesting!

  • my hisory teacher told us about this today in class! its awesome!!!

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