In the forests of Mount Iwaki, northern Japan, macaques have been gathering at hot springs for decades, their rust-colored fur frosted with snow as they soak in water heated by the volcano beneath them. Nobody quite remembers when this started—sometime in the 1960s, maybe earlier—but the monkeys figured out that volcanic warmth beats hypothermia.
Here’s the thing about sacred animals living on active volcanoes: they’re basically squatting on geological time bombs, and somehow that makes them holier.
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The long-tailed macaques of Mount Batur in Bali have turned volcano-dwelling into an art form. The temple complex at Pura Ulun Danu Batur, perched at 1,500 meters on the caldera rim, has been rebuilt four times since 1917 because the volcano keeps destroying it. Yet the monkeys stick around, treated as sacred guardians of the shrine despite their habit of stealing offerings and terrorizing tourists. Mount Batur last erupted in 2000, sending ash columns 300 meters high, and the macaques barely flinched.
Turns out the volcanic soil grows better fruit trees.
At Sakurajima in southern Japan—which erupts roughly 800 times per year, making it one of the world’s most active volcanoes—Japanese macaques inhabit the surrounding forests and occasionally wander into evacuation zones. Local Shinto shrines consider them messengers of the mountain gods, which is a convenient theological explanation for why they refuse to leave despite living in what amounts to a geological war zone. The volcano has been in near-constant eruption since 1955, producing ash clouds that regularly blanket the nearby city of Kagoshima, population 600,000.
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Wait—maybe the monkeys aren’t being spiritual. Maybe they’ve just done the math on predator density versus volcanic risk and decided that leopards are scarier than lava.
Indonesia’s Mount Merapi, which killed 353 people in its 2010 eruption, hosts colonies of long-tailed macaques around several Hindu and Buddhist temples on its slopes. The Cetho temple, dating to the 15th century, sits at 1,400 meters elevation. The monkeys there have learned to time their temple raids around prayer schedules, maximizing banana aquisition while minimizing human interference. Volcanologists monitoring Merapi’s seismic activity have documented macaques descending to lower elevations days before eruptions—possibly sensing infrasonic vibrations humans can’t detect, or possibly just getting lucky.
Nobody’s funded the research to find out which.
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The sacred monkeys of Mount Agung in Bali remained at the Besakih temple complex during the 2017 eruption that displaced 140,000 people and closed the airport for days. Balinese Hindus consider Besakih the “Mother Temple,” and the resident macaques are supposedly reincarnated ancestors. When pyroclastic flows came within 4 kilometers of the temple, the monkeys relocated to the temple’s lower courtyards but didn’t leave entirely, which locals interpreted as a divine signal that the worst danger had passed.
The volcano disagreed, erupting again three days later.
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Mount Bromo in East Java hosts the Tenggerese people, who throw vegetables, livestock, and money into the crater annually to appease the mountain gods. The crab-eating macaques living in the surrounding Bromo Tengger Semeru National Park have apparently figured out this schedule, because they congregate near the caldera rim during ceremony season, scavenging whatever doesn’t make it into the crater. Bromo’s last major eruption in 2016 killed two people; and sent ash 3,000 meters into the atmosphere, but the monkey population rebounded within months.
Volcanic ecosystems recover faster than you’d think—the nutrient-rich ash acts like geological fertilizer, and within a year the forests are denser than before. The monkeys know this, even if the theology comes later.
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At Rabaul in Papua New Guinea, where the 1994 eruption buried the town under meters of ash, feral pig populations (not monkeys, but close enough in the sacred-animal-on-volcano paradigm) returned to the caldera within three years. Local Tolai people consider them spirit animals connected to their ancestors and the volcano’s moods. The pigs root through the ash for buried vegetation, and occasionally fall into fumaroles—which hasn’t made them any less sacred, just more cautious.
Maybe that’s the real lesson here: when your habitat keeps trying to incinerate you, you learn to pay attention to the ground rumbling.
