- Indonesia’s critically endangered Javan rhinos appear to have weathered a recent volcanic eruption near their only remaining habitat, highlighting the precarious position of one of the world’s rarest large mammals.
- With the entire wild population concentrated in one coastal national park, the species faces risks from natural disasters as well as the challenges of conservation and population management.
- Efforts to give the rhinos greater protection have included plans for a second habitat and attempts to move animals to safer areas.
Indonesia’s critically endangered Javan rhinos appear to be safe despite an ongoing eruption of Mount Anak Krakatau near their last remaining habitat, conservation authorities said.
Ardi Andono, head of Ujung Kulon National Park, home to the world’s only wild population of Javan rhinoceros (Rhinoceros sondaicus), said on Sep. 7 that the rhinos’ habitat had been minimally affected by vibrations and noises from Anak Krakatau, which began erupting on Sep. 4. Mount Anak Krakatau, an active volcanic island in the Sunda Strait between Java and Sumatra, lies about 50 kilometers (31 miles) from the park on Java’s southwestern tip, and its recent eruption sent ash across parts of both islands, disrupting air travel and prompting some schools and fishing activities to halt.
“The Javan rhinos remained safe and still appear normal,” Ardi told Mongabay in a WhatsApp message, adding that his park rangers continue to stand on guard.
The number of Javan rhinos remaining in the wild is disputed. Save the Rhino, a conservation group, estimates there are about 50, while Indonesia’s forestry ministry puts the population at 87 to 100. The government’s figures have previously faced scrutiny after a 2023 investigation by Indonesian environmental group Auriga Nusantara found that rhinos not seen by camera traps for years, including some later confirmed dead, were still included in official counts.
The discrepancy is significant because the species is confined to Ujung Kulon National Park on the western tip of Java, making it particularly vulnerable to threats in a single habitat. Since 2011, official counts had shown the population steadily increasing, but Auriga’s 2023 investigation found evidence that the government’s method could overstate the number of living animals.
Riszki Is Hardianto, a wildlife conservation researcher at Auriga and co-author of a 2023 report on Javan rhinos, said he had not received reports of any rhino deaths linked to the eruption. “What’s threatening the Javan rhinos is if a tsunami occurs there,” he told Mongabay in a WhatsApp message on Sept. 10.
Once widespread across South and Southeast Asia, the Javan rhino has lost most of its historical range to hunting and habitat loss and is now confined to Indonesia’s Ujung Kulon National Park, meaning the loss of this population would result in the species’ extinction in the wild, erasing an entire evolutionary lineage with no wild population left from which it could recover.
Tsunamis have long been considered a major threat because the rhinos live in low-lying coastal habitat; a tsunami that struck Ujung Kulon in December 2018 killed one rhino and highlighted the vulnerability of a population concentrated in a single area. The disaster renewed calls for a second habitat away from tsunami-prone areas.
Conservationists have long urged Indonesia to establish a second habitat for Javan rhinos to reduce the risk of the entire population being wiped out by disease or a natural disaster. A leading candidate, the 5,000-hectare (12,355-acre) Cikepuh wildlife reserve on Java’s southern coast, was ruled too risky in 2019, because it was also used for military training, prompting the government to focus instead on expanding suitable habitat within Ujung Kulon.
Indonesia has also begun moving individual rhinos within Ujung Kulon as part of efforts to manage the species’ small population and limited genetic diversity. But the first such translocation ended in November 2025 when a male rhino named Musofa died days after being moved to the Javan Rhino Study and Conservation Area; a necropsy found severe parasitic infection and chronic health problems, highlighting the risks of moving animals that are already vulnerable.
Basten Gokkon is a senior staff writer for Indonesia at Mongabay.
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