MANILA—Scientists from University of the Philippines (UP), the National Museum, and Field Museum of Natural History in the United States have discovered 3 species of giant cloud rats, locally known as buot or bugkun, that lived only in the Philippines until they went extinct some 2,000 years ago, according to their study published Friday.

"These are three previously unknown species from an unusual group of rodents, locally known as buot or bugkun, and known in English as giant cloud rats, that live only in the Philippines," said Dr. Janine Ochoa, anthropology assistant professor at UP Diliman and lead author of the journal paper published by the Journal of Mammalogy.

The researchers found fossil species of the rats in Callao Cave and several adjacent smaller caves in Peñablanca town, Cagayan, with some specimens located in the same deep layer where the Homo luzonensis was discovered in 2019.

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Callao Cave has been the subject of excavations of the National Museum as early as 1979.

Co-author Marian Reyes, zooarchaeologist at the National Museum of the Philippines, said the giant rats were "members of an ancient branch on the tree of life that arrived from the Asian mainland about 14 million years ago and live only in the Philippines."

Buots dwelled in trees and ate leaves, buds, and seeds, according to Reyes. They also have "furry or fluffy tails and striking fur colors."

EXTINCTION

The study said that of the 3 rat species discovered, 2 went extinct only 2,000 years ago.

"Our records demonstrate that these giant rodents were able to survive the profound climatic changes from the Ice Age to current humid tropics that have impacted the earth over tens of millennia. The question is, what might have caused their final extinction?" said Philip Piper, a co-author based at the Australian National University.

Co-author Dr. Armand Mijares of the UP Diliman Archaeological Studies Program, who headed the excavations of Callao, offered a clue.

"A clue might be in that the last recorded occurrence of two of the species is around 2,000 years ago or shortly after. This is after the first arrival of agricultural societies and the introduction of animals like domestic dogs, pigs, and macaque monkeys in Luzon... While we can’t say for certain based on our current information, this implies that humans likely played some role in their extinction," Mijares said.

Added Dr. Lawrence Heaney, Negaunee Curator of Mammals at the Field Museum of Natural History in Chicago and another co-author of the study: "The two that became extinct [more recently] were giants among rodents, both weighing about a kilogram. They were big enough that it might have been worthwhile to hunt and eat them."

Heaney said the study showed how "Philippines has the greatest concentration of unique species of mammals of any country."

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