“Lost” giant rat found alive in Papua mountains after 30 years

Bringing a Lost Species Back Into View

The Subalpine Woolly Rat (Mallomys istapantap) was first identified in 1989 from museum samples and had not been recorded in the wild for three decades. It had never been photographed until now. The new field data and imagery collected by Vejmělka provide crucial insight into this rarely seen species and shed new light on the extraordinary mammalian biodiversity of New Guinea's remote highlands.

A Mysterious Giant of the Highlands

"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?" says Vejmělka. Alongside the groundbreaking photos and videos, he obtained the first biometric measurements of male specimens and documented details about the animal's diet, parasites, movements, and daily behavior.

New Guinean woolly rats, related to the giant cloud rats of the Philippines, rank among the largest murine rodents on Earth. They live only in the steep, rainforest-covered highlands of New Guinea. In the absence of other competing placental mammals, these rodents have diversified over roughly five million years into a surprising array of distinct forms and species.

Life of the Subalpine Woolly Rat

The thick-furred Mallomys istapantap leads a secretive life in isolated, high-altitude regions. Active at night, it climbs trees in search of food and takes shelter during the day in burrows or among tree branches. Feeding exclusively on plant material, it has sharp incisors, dense fur, 8 cm-long paws, and a total body length (including tail) of about 85 cm. Weighing up to 2 kg, it is both imposing and elusive. Its nocturnal behavior and inaccessible habitat have made direct observation extremely rare.

Science Meets Traditional Knowledge

"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," says Vejmělka. During his six-month expedition, he worked closely with several local tribes while surveying the mammalian diversity of Mount Wilhelm (4,509 m), the highest peak in Papua New Guinea, from base to summit. He documented and genetically identified 61 species of non-flying mammals (rodents and marsupials) found along the mountain.

This fieldwork deepens scientific knowledge of the incredible but still underexplored wildlife of New Guinea's tropical mountains. While similar habitats in regions such as the Americas, Africa, and Southeast Asia have been studied extensively, the Australasian highlands remain far less known. Collaboration with local communities is a vital part of this progress.

Through these shared research efforts, indigenous groups gain awareness of their region's unique natural heritage and the importance of protecting it from increasing threats, including mining.

The findings have been published in the scientific journal Mammalia.