A "Giant Woolly Rat" was just photographed for the first time ever, proving it's not a myth
High on New Guinea’s mist-wrapped peaks, hunters told stories of a shaggy rat as long as a house cat and as heavy as a newborn baby. Those tales floated through villages for decades, yet no scientist had ever confirmed that Mallomys istapantap was actually alive.
That has just changed, thanks to an expedition that spent half a year in terrain so steep that climbers joke the ground leans back at them.
The team’s cameras – perched between 10,500 and 12,140 feet – caught the subalpine woolly rat (Mallomys istapantap) padding along mossy logs at night.
By day, they found claw marks on trunks and neat burrow entrances hidden under roots. After all that waiting, the legend turned out to be very real.
Mallomys istapantap‘s life in the trees
New Guinea’s highlands form an island in the sky. Temperatures drop sharply, oxygen thins, and forest giants shrink into stunted, lichen-covered trees.
Up here, mammals have carved out odd niches. Some marsupials bounce like wallabies among alpine grasses, and this particular rat has taken on the role of a miniature herbivore with a supersized coat.
Most rodents lose heat quickly, yet this one sports a dense pelt that seals warmth as efficiently as a parka. Such insulation lets it explore chilly ridge tops around 12,140 feet without slowing down.
Evolution has also gifted it paws three inches long – snowshoe-like pads that spread its weight on soft ground.
Tracking a mythical creature
The hunt relied on both technology and tradition. Motion-triggered cameras watched narrow game trails while local guides read subtle signs that outsiders would miss.
The reward: the first wild photographs and videos of Mallomys istapantap, three decades after museum drawers last saw a specimen.
“It’s astonishing that such a large and striking animal has remained so poorly studied. How much more is there to discover about the biodiversity of tropical mountains?” said the project’s lead researcher.
Only after those images surfaced did the world learn the rat’s true dimensions. Nose to tail, it stretches 33 inches and tips the scale at about 4.4 pounds – three times the heft of a city rat.
Males boast stockier builds than earlier museum skins hinted, and one newly noted trait is a tufted tail tip that may aid balance in the canopy.
Mallomys istapantap – a gentle giant
Despite its bulk, Mallomys istapantap leads a quiet, vegetarian life. Night-vision footage shows individuals clambering into tree crowns for tender shoots, then descending to burrows before sunrise.
No evidence of meat-eating appeared during the six-month survey; instead, stomach samples held leaves, seeds, and a smattering of forest fruits.
Parasite checks turned up fleas and mites unique to the highlands, hinting at long isolation.
Genetic analysis supports that idea: the rat and its woolly cousins split from other murid rodents roughly five million years ago, diversifying in alpine pockets while lowland ecosystems filled with competitors.
Partners in the climb
Fieldwork at 14,793-foot Mount Wilhelm demanded cooperation with several indigenous tribes whose territories span the slope from base to summit.
They pointed out feeding sites, shared traditional names, and, crucially, advised when weather made certain gullies unsafe.
“If it weren’t for the indigenous hunters who accompanied me in the mountains and helped me locate the animals, I would never have been able to collect this data,” said the expedition’s leader, a doctoral candidate from the Biology Center of the Czech Academy of Sciences and the University of South Bohemia.
Their joint efforts documented and genetically identified 61 non-flying mammal species along the mountain – an inventory that will guide future conservation.
More than one revelation
Besides fresh footage, the scientists obtained the first tissue sample in 30 years.
Laboratory work confirmed earlier suspicions that Mallomys istapantap sits near the top end of rodent size limits, rivaled only by Philippine cloud rats.
Measurements of males filled gaps left by historical female specimens and revealed subtle cranial differences, suggesting there could be unrecognized sister species in neighboring ranges.
Detailed activity logs also shattered the assumption that the rat stays ground-bound.
Cameras repeatedly caught it scrambling along horizontal branches six feet above ground, proving an arboreal streak that may protect it from valley predators.
Why Mallomys istapantap matters
When a creature this conspicuous can evade science until 2025, it highlights how little is known about alpine tropics.
These mountaintops act as natural laboratories for studying evolution under climate stress, yet mining roads and warming temperatures threaten to push sensitive specialists uphill until there is nowhere left to go.
New images of the subalpine woolly rat won’t save the species on their own, but they provide a face for conservation campaigns.
They also remind policymakers that undiscovered wonders still rustle in the cold mists, waiting for the next curious eyes to look up rather than forward.
The full study was published in the journal Mammalia.
Image credit: Czech Academy of Sciences
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