A new study reports that extreme rainfall in Indonesia’s North Sumatra in November 2025 contributes to deaths of the critically endangered Tapanuli orangutan, one of the rarest great ape species. The research estimates that about 58 of the remaining roughly 800 Tapanuli orangutans die after more than 1,000 mm of rain falls over four days, the period associated with severe weather events in the region. The study calculates this as approximately 7% of the global Tapanuli orangutan population and about 11% of the local population affected. It also connects the deaths to climate-related impacts described in the report, including flooding and landslides that occur alongside the heavy rain. Conservation groups and other observers cited by reporting on the findings express concern that such extreme weather could further threaten the species’ survival, given its very small population and limited habitat. The study’s findings come as researchers and policymakers continue to assess how changing weather patterns affect threatened wildlife in Indonesia and beyond.