Indonesian wildfires threaten world's longest orangutan study as apes flee Borneo

In the forests of Borneo, a fire is moving toward one of the world's most valuable repositories of knowledge about wild apes. Flames have already crept within 200 metres of Rangkong research station, a satellite facility of Cabang Panti, which sits roughly four miles north inside Gunung Palung national park in West Kalimantan province. The station is home to what may be the longest continuous study of orangutans in existence—32 years of unbroken observation led by Cheryl Knott, a biological anthropologist at Boston University. If the fire reaches the main research camp, as scientists now predict it will within 20 days, it will not simply destroy a building. It will erase a dataset that has no equal.

Hundreds of Bornean orangutans live in the immediate vicinity of these research stations, part of a population of more than 2,500 thought to inhabit the park. All three species of orangutan are classified as critically endangered. The animals are already moving. Researchers have documented five individuals from their long-term study population fleeing the flames, some only metres ahead of the fire's edge. These are apes whose lives have been tracked from birth through to grandmotherhood—animals whose reproductive patterns, social structures, and survival strategies have been recorded in meticulous detail across three decades. Now they are running.

The fires themselves are not accidental. In Indonesia, land clearing by fire is routine practice, done annually to prepare ground for agriculture and development. But this year, an exceptionally strong El Niño has warmed sea-surface temperatures across the equatorial Pacific, disrupting weather systems globally and creating conditions of extreme heat and dryness across Indonesia. In some areas of West Kalimantan, months have passed with virtually no rain. The fires that were meant to be controlled have instead escaped, spreading rapidly through forests that should be too wet to burn. What happens on Borneo does not stay contained—it becomes part of a global climate story.

The research conducted at Cabang Panti has fundamentally altered how science understands orangutans and, by extension, primate reproduction itself. The station's scientists discovered that Bornean orangutans reproduce on an eight-year cycle—the longest birth interval of any mammal on Earth. This finding emerged not from theory or laboratory work, but from patient, continuous observation of the same individuals over decades. The database is, in Knott's words, unparalleled in its scope and detail. Andrew Marshall, an anthropologist at the University of Michigan who ran an orangutan project at the site from 2000 to 2020, emphasizes what is at stake: the station protects one of the few truly ecologically intact tracts of lowland tropical rainforest remaining in Borneo. Without the long-term field data that only such a place can generate, scientists cannot understand how tropical ecosystems respond to or suffer under global climate shifts.

On the ground, the response has become desperate. More than 40 people—field assistants, station staff, and local villagers—are working around the clock to defend Rangkong research station. They have built a firebreak and constructed an improvised sprinkler system using punctured hose lines to saturate the peat soil surrounding the facility. The peat is critical: once fire reaches a peat swamp, it can smoulder underground for months, even after surface flames are extinguished. Keeping the ground wet is the only defence. Yet Caitlin O'Connell, deputy director of the Gunung Palung orangutan conservation programme, is clear about the limits of what local effort can achieve. The scale of the crisis has overwhelmed local capacity. What is needed is large-scale water bombing and trained firefighters—resources that, as of now, have not materialized.

But even if the research station survives, the victory may be hollow. Orangutans are solitary animals that require vast ranges and live at low population densities. They cannot be crowded together in whatever forest remains. If the fire consumes the habitat, the building becomes an empty monument. Knott articulates the paradox plainly: if the orangutans are gone and their food sources are destroyed, what is there left to study? The forest is not incidental to the research. It is the research. Without it, there is only a structure.

Indonesian meteorologists forecast an intense fire season extending through October as climate models predict El Niño will intensify. The hotspots are everywhere. O'Connell does not shy from the implications: what was thought to be unburnable could vanish entirely if dry conditions persist for months. The countdown to Cabang Panti is 20 days. The countdown to the end of the fire season is much longer.