4 Days of Rain Wiped Out 7% of Rarest Great Ape

A four-day deluge in Indonesia killed off 7% of an entire species of endangered great ape, a new study has found. Researchers say roughly 39 inches of rain fell as Cyclone Senyar hit Indonesia's North Sumatra province last November, triggering landslides that, per satellite imagery, brought down about 20,000 acres of the Tapanuli orangutans' habitat. They are the "great ape species with the smallest wild population," per the study published Wednesday in Current Biology, and live in in three isolated populations (West, East, and South Block) in Batang Toru.

The researchers estimate 58 of the 800 known apes lived in the landslide-affected areas and were killed; that's about 7% of the world's remaining population and 11% of those living in their core West Block habitat. The BBC reports the authors consider those figures "conservative" ones, as they do not factor in canopy breakage or reduced food availability caused by the rain. The Guardian reports the authors estimate human-driven warming boosted rainfall intensity by up to 50%. The Indonesian government has temporarily halted major industrial activity in the Batang Toru ecosystem so that scientists can study what can be done to protect the species.