In the dead of night, a giant rat the size of a small terrier scurries among the forest ferns in the wet, glacial valley of Papua New Guinea's highest mountain.
Little does it know, it is being caught on candid camera.
For the first time, the subalpine woolly rat — the biggest rodent in Australia and Oceania — has been documented in Papua New Guinea's Mount Wilhelm.
While the shaggy-furred rat was well-known by local hunters, it had not been photographed live in its habitat by the scientific community until now.
"There is one book I was working with, on the mammals of PNG, and there is just a painting of his huge animal without any pictures," said biologist František Vejmelka.
"These are the first live pictures, and I just love it."
Only about 50 specimens — mostly of the rats' skulls — existed in scientific collections and most pictures of the rodent, other than a photograph of a preserved museum specimen, were painted illustrations.
Being nocturnal, not particular noisy, and a drab shade of grey meant the tree-climbing rat also was hard to spot.
"When scientists first described it in 1989, they assumed it was herbivorous based on the shape of their molars of their teeth," Mr Vejmelka said.
But he confirmed this by purchasing rats local hunters caught to examine the rats' stomach contents, which were filled with ferns.
Mr Vejmelka also documented their reddish-brown chests, a trait previously characterised as an "artefact" in existing literature.
Measuring about 75 centimetres from head to tail and weighing about 1.5 kilograms, Mallomys istapantap is an elusive creature, only found in the eastern part of New Guinea's mountains.
Mr Vejmelka said the rodent's Latin name means "it's on the top right" in the local Melanesian pidgin dialect, reflecting its habitat 3,000 meters above sea level, higher than where locals lived.
Not endangered, just camera-shy
The University of South Bohemia mammalian researcher published his findings in the journal Mammalia in April after spending six months among Papua New Guinea's highest peaks looking for the giant rat along with 60 other rodent species.
He said standard trapping did not work in the mountainous forests, so he set up camera traps and joined local landowners on night hunts to find the shaggy critter.
Mr Vejmelka said the scientific community's lack of understanding of the rodent was a reflection of its remote habitat rather than its numbers.
"During my time spent there working with the hunters I could see that they were actually pretty abundant.
"One time when we were in the camp up in the mountains, there was a hunting dog who just ran off and immediately came back with the rat in its mouth."
He credited the local community and indigenous hunters for helping him with his PhD research into the island's fauna and hoped to return and continue his work
"The mammals of the island and the biodiversity is so poorly known still, that it's really a place for a lifetime of scientific work."
