Scientist reveals world-first footage of subalpine wooly rat, a rodent species as big as a domestic cat

Daily Mail​

22-05-2025

A scientist has discovered a species of rat that measures more than 2.5ft-long in Papua New Guinea.
The species, called the subalpine woolly rat, has sharp incisors, thick fur, and clawed paws measuring three inches.
It is three times the size of a brown rat and new footage has revealed one of them scampering across a tree branch at night, likely in search for food.
Frantisek Vejmelka works for the Biology Center of the Czech Academy Of Sciences and the University of South Bohemia, Czech Republic.
He said: '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?'
The species only lives in the steep highlands of Mount Wilhelm, Papua New Guinea.
Until now, the subalpine woolly rat (Mallomys istapantap) has been known to science only from a handful of museum specimens.
First described in 1989 based on historical museum material, it was last recorded 30 years ago and had never before been photographed.
But the Czech researcher's new photos and video footage show the animal in its natural habitat for the first time.
During his six-month expedition, he worked with local tribes to survey Mount Wilhelm, the highest peak in Papua New Guinea which reaches 14,793ft above sea level.
According to expert's measurements, the subalpine woolly rat is a length of 2.7ft, including the tail and weighs nearly 4.4lb.
This compares to an average length of about 2.3ft of 8lb to 10lb for the domestic cat.
Meanwhile, the average brown rat today has a body length of about 11 inches and usually weighs 0.44-0.66lb.
Vejmelka also gathered data on the rat's diet, parasites, activity patterns, movement, and other aspects of its lifestyle.
According to the expert, the nocturnal species leads a hidden life in remote, hard-to-reach areas, which explains why it's so understudied.
It climbs trees at night, hides in underground burrows or tree canopies during the day, and feeds exclusively on plant matter.
Vejmelka's work, published in the journal Mammalia, contributes to a deeper understanding of the biodiversity of New Guinea's underexplored tropical mountains.
He said: 'These are the first specimen records in 30 years for this spectacular mammal poorly known to science.
'Camera trap images and video, as well as photographs of the habitat and hunting with indigenous people, deepen our understanding of the activity patterns, locomotion, diet, intrageneric elevational partitioning, and behavioral ecology of the woolly rats.'
New Guinean woolly rats, together with the giant cloud rats of the Philippines, are the largest rodents belonging to the murine family.
They are found only in the steep highlands of New Guinea covered in pristine rainforest.
However, the subalpine woolly rat is not the largest rat in the world.
The world's biggest rat in terms of length is the Gambian pouched rat (Cricetomys gambianus), which reaches 3ft-long, including the tail, which makes up half of its total length.
Another big rat species is the Malagasy giant rat (Hypogeomys antimena) found in Madagascar, which can grow to about 2ft.
But the largest rodents to ever have walked the Earth – including Josephoartigasia monesi and Phoberomys pattersoni – are now extinct.
Unusually large animals from history known as 'megafauna' typically died out due to climate and environmental shifts, plus human hunting.