Across the limestone ridges of Ha Giang province, in the far north of Vietnam, broad-leaved trees form a canopy so dense it barely lets any light through.
Somewhere in those branches, a pair of blue eyes—the unmistakable hallmark of a species found nowhere else on Earth—gazes down at the forest below. This is the Tonkin snub-nosed monkey (Rhinopithecus avunculus), and catching a glimpse of one is a rare privilege.
A new census of the Khau Ca conservation area, carried out in October and November 2025 and published in May 2026 by Fauna & Flora International, documented 160 individuals within the reserve.
That’s more than triple the population recorded when the site was first designated as critical habitat for the species in 2002 — back then, only 50 animals were counted.
Today, Khau Ca is home to roughly 80% of the world’s known Tonkin snub-nosed monkeys.
An Animal the World Thought Was Lost
The Tonkin snub-nosed monkey is endemic to northern Vietnam.
It has black-and-white fur, an upturned pink nose, and patches of pale blue skin around its eyes. First described in 1912, the species was rediscovered in 1989, when a survey turned up just 200 individuals in Ha Giang province.
In the decades in between, the species was presumed extinct.
Intensive hunting for traditional medicine — and, to a lesser extent, for food — had driven numbers down so drastically that by the 1980s, most scientists had written the animal off as extinct.
In 2002, Fauna & Flora discovered a population of global importance in the Khau Ca forest. Five years later, the organization found a second population in an isolated patch of forest near the Chinese border, which was later confirmed as the second-largest known population of the species.
The Most Thorough Census Yet
The 2025 census was the most comprehensive yet.
More than 30 people, working in 10 teams, spent 10 days covering the reserve’s 2,470 acres. They divided the area into sectors to prevent double-counting and improve accuracy.
Teams used thermal-imaging drones, camera traps, and acoustic sensors that could pick up the monkeys’ calls.
Canh Xuan Chu, who leads Fauna & Flora’s Tonkin snub-nosed monkey conservation program, has worked on the ground there for seven years.
According to Chu, telling individual animals apart isn’t all that difficult. Each monkey has its own distinct coloring and tail markings, and their calls are different enough to tell them apart reliably.
The late-2025 count confirmed that the Khau Ca population is still growing steadily, and several newborns were among the 160 individuals recorded.
Tran Van On, a member of Fauna & Flora’s community conservation team, noted that local communities have grown far more aware in recent years of the need to protect the species and its habitat.
After the population was discovered in 2002, Fauna & Flora established a field station and set up community patrol groups to remove snares, spot illegal logging, and report signs of poaching. For communities that had long depended on the forest for their livelihoods, these programs offered an alternative source of income.
Organizations, including the Denver Zoo, distributed fuel-efficient cookstoves that cut firewood use by half, easing pressure on the forest.
The combination of formal protection, community engagement, and reduced reliance on the forest has produced the result conservationists are now seeing: a tripling of the population over two decades.
What Is Happening in Quan Ba
The contrast with the Quan Ba forest, a few hours’ drive away, is hard to miss.
For years, Quan Ba was home to the second-largest known population of Tonkin snub-nosed monkeys. Patrol teams haven’t spotted the species there since 2020. The most recent census, conducted in 2024, found no trace of the animals.
The main problem, according to Chu, is cardamom farming inside the forest.
Cardamom fetches high prices in food and medicinal markets, making it a valuable crop for local communities. But growing it means opening up the canopy, and the harvested pods have to be dried over firewood — both of which damage the ecosystem the monkeys rely on.
Unlike Khau Ca, Quan Ba has no formal protected-area status, which limits the legal tools available for long-term habitat management.
Fauna & Flora still keeps a patrol team there, in case a few monkeys are hanging on in hard-to-reach spots. The organization is now working to set up biodiversity corridors linking Khau Ca with Quan Ba, in the hope that the recovering population might eventually return.
A Fragile Recovery
The total population of the species is estimated at around 250 individuals.
With 160 of them concentrated in a single 2,470-acre reserve, Khau Ca is critically vulnerable. A disease outbreak, a severe weather event, or a resurgence of poaching could undo decades of work almost overnight.
The International Union for Conservation of Nature (IUCN) classifies the Tonkin snub-nosed monkey as Critically Endangered — one step away from extinction in the wild.
The species is listed among the 25 most threatened primates on Earth.
What has happened in Khau Ca shows that community-based conservation can reverse decades of decline.
What is happening in Quan Ba is a reminder that without formal protection and real economic alternatives for the people who depend on the forest, the result can be exactly the opposite.
For now, the Tonkin snub-nosed monkey hangs in that precarious balance.
