Between the branches of Khau Ca's limestone forest in northern Vietnam, a pair of blue-ringed eyes watches across the canopy — a rare and precious sight. Canh Xuan Chu, field conservationist with Fauna & Flora International, knows to treasure these glimpses, because the Tonkin snub-nosed monkey was once believed extinct, hunted so relentlessly for traditional medicine and bushmeat that it vanished from sight entirely during the 1980s. Today, after decades of near-invisibility, the species is staging a quiet comeback in one forest that may offer a blueprint for saving one of the world's most endangered primates.
The stakes are staggering. Tonkin snub-nosed monkeys exist nowhere else on Earth — they are endemic to Vietnam, found only in fragmented patches of forest across two northernmost provinces that border China. When conservationists rediscovered the species in the late 1980s and 1990s, they found only scattered survivors clinging to survival. When a population of just 50 was confirmed in Khau Ca in 2002, it represented a precious lifeline for an animal that had nearly vanished forever.
Two decades later, that lifeline has grown into something more resilient. A comprehensive census completed in October and November 2025 — the most thorough survey ever conducted — revealed that Khau Ca's population has more than tripled to 160 individuals. More striking still: these 160 monkeys now represent an estimated 80 percent of the entire remaining species on Earth. The discovery marks one of conservation's quiet successes: what once seemed like a species teetering on the brink of permanent extinction is reproducing, surviving, and thriving in one protected corner of the world.
The survey itself was a feat of modern conservation methodology. More than 30 people from the conservation unit and local communities divided into 10 groups, camping in the 1,000-hectare reserve for 10 days. They used thermal imaging drones, camera traps, and audiomoths — smart acoustic sensors that detect the monkeys' distinctive calls — ensuring no individual was counted twice. For Chu, who has worked on the project for seven years, spotting individuals remains easier than the technology might suggest: "You see the coloring, you see the tail; and the other thing is, their calls to each other are different, so it's very clear."
The recovery reflects a coordinated, human-centered approach to conservation that extends far beyond the forest itself. Shortly after the 2002 discovery, Fauna & Flora established a conservation field station and built community conservation teams to patrol the reserve, removing snares and reporting signs of illegal hunting or logging. Recognizing that local communities traditionally relied on the forest for income, the project created alternative livelihoods through patrol work itself. Partner organizations like the New Nature Foundation and Denver Zoo distributed fuel-efficient stoves that cut firewood consumption by half, reducing pressure on forest resources. The results have been measurable: community member Tran Van On observed a "significant increase" in local awareness and protection efforts, with residents now more conscious of both the endemic species and the broader forest ecosystem it depends on.
The contrast with other locations is sobering. Quan Ba, once home to the second-largest population, has seen its monkeys disappear. But Khau Ca's success suggests a different future is possible. If other fragmented forests in Vietnam can replicate this model — combining protection with community partnership, habitat restoration with alternative income sources — the Tonkin snub-nosed monkey may yet move from the edge of extinction toward genuine recovery.