ByStefan Lovgren
Published December 20, 2023
• 8 min read
Da Nang, VietnamIn this central Vietnamese city of 1.2 million people, almost every inch of land has been gobbled up by developers. Towering hotels line a miles-long white sand beach. But one prime piece of real estate remains mostly untouched: the mountainous and forested tip of the city’s peninsula. It is a 6,400-acre nature reserve called Son Tra, or, as it’s also known, “Monkey Mountain.”
The reserve, which is also home to a military base, is a last refuge for the red-shanked douc, a critically endangered langur that numbers only about 2,000 animals in Son Tra. On a recent visit, conservationist Hoang Van Chuong quickly spotted several brightly colored, long-tailed monkeys high in the treetops. “It’s hard to hide with those features,” chuckled Chuong, development director for the local nonprofit GreenViet.
Preoccupied with some late afternoon leaf snacking, the animals didn’t seem too bothered by our presence. But the doucs have good reason to fear humans. Long hunted both for meat and medicine, they have lost much of their native forest habitat, which once extended across the region. Driven into tiny jungle enclaves, they’re today found only in a few pockets of Laos and in two isolated populations in Vietnam, the largest of which clings on here in Son Tra.
The doucs are among the many species that have suffered huge declines because of habitat fragmentation, which studies show is the biggest driver of biodiversity loss globally, and especially in Southeast Asia. Urban growth is a major contributor to the problem. City populations worldwide are poised to increase by 2.5 billion over the coming 30 years, tripling the global footprint of cities. Experts warn that animals unable to adapt to urban settings may be pushed into ever-smaller, isolated spots. (Read about a new monkey species hiding in plain sight in Southeast Asia.)
“Species that require relatively large, intact areas of wildland,” like the red-shanked doucs, “will be lost, [while] native and introduced species that thrive in cities may take their place,” says Rohan Simkin, an ecologist at Yale University, who studies impacts of urban expansion on wildlife.
He and other researchers say there are likely many more urban “avoiders”—species unable to adapt to urban environments—than urban “adapters,” though no major studies have been conducted to confirm this.
Our peninsula, our monkeys
Douc is an old Vietnamese name thought to mean monkey. In addition to the red-shanked douc, there are two other douc species in Southeast Asia, also critically endangered: the black-shanked and gray-shanked douc. Some deforestation can be traced back to the Vietnam War, when forests were sprayed with the toxic defoliant known as Agent Orange. As the Vietnamese government’s focus remained squarely on growing its economy in the years following the war, wildlife protection received scant attention.
As recently as a decade ago, few people in Da Nang even knew the doucs existed in Son Tra, according to Larry Ulibarri, an anthropologist at the University of Oregon in Eugene, who wrote his doctoral thesis on the species. When Ulibarri showed photos of the animals to local officials, he was told “those primates are in Africa, not here.”
But recognition of the doucs began to grow when GreenViet, which was formed in 2014, and other conservationists started organizing photo exhibits, school visits, and other outreach programs.
“People realized, this is our peninsula and these are our monkeys … and asked, what can we do to protect them?” says Chuong. Local hotels began asking for photos of the langurs that they could display in their lobbies.
Plans unveiled by developers in 2016 to build several seaside resorts inside the reserve led to a public outcry. Campaigners collected 10,000 signatures protesting the project, an unusual display of public opposition in Vietnam. When national leaders joined the call, the project was scrapped.
“The reason why Son Tra has not been developed is because the monkeys [are there],” says Ulrike Streicher, a German veterinarian who spearheaded the early outreach efforts.
Though Son Tra’s military staff has intercepted poachers, hunting is no longer considered a major threat in the reserve.
To adapt or not adapt
Globally, around half of all original forests have disappeared, with the loss most acutely felt in tropical forests that house at least half of the world’s species. In addition to urban growth, agricultural expansion and logging are major drivers of forest loss in Southeast Asia and elsewhere. Sometimes that loss occurs rapidly, but more often it can be incremental, especially in protected areas.
Species that can adapt to and even thrive in disturbed landscapes or urban environments tend to have wide-ranging diets and an ability to quickly solve problems, like finding a place to sleep in a busy city. Many are small-bodied animals, like mice and rats, but they also include deer and medium-size predators, such as North America’s coyotes. (Read how wild animals are adapting to city life in surprisingly savvy ways.)
But there are likely many more animals that are unable to make those adaptations. One example is the endangered Florida panther, which is highly threatened by urbanization, with only around 200 individuals remaining in the wild. The big cat needs sprawling territories to survive and find other individuals with which to mate.
The red-shanked douc has similar needs. One family of doucs, which normally ranges from four to 15 individuals, likely requires at least 30 acres of forest habitat, according to Chuong. If living space is too limited, animals may end up inbreeding, resulting in lineages that are less robust and genetically viable.
On the encouraging side, red-shanked doucs have a relatively flexible diet, feeding primarily on buds and young leaves, but also eating flowers, fruits, seeds, and bark.
Colorful costume
In Son Tra, ecotourism has begun to connect people with their native wildlife. GreenViet, for instance, organizes daily monkey-viewing tours for the public. Because the doucs are not naturally curious animals and generally stay high in the trees, eating their own food, the risk of them being habituated to humans is considered small.
With their extravagant appearance, which have earned them the erroneous nickname “costumed ape,” they are, however, a sight to behold. “Many people tell us that seeing the doucs is a once-in-a-lifetime experience,” says Võ Hồ Quế Anh, who leads the GreenViet tours. The organization says it has so far reached about 30,000 people through its educational outreach programs.
The work appears to be paying off. Greenviet’s census of the Son Tra douc population in 2017 registered around 1,300 individuals. A new survey, yet to be published, suggests the number has grown to more than 2,000.
“It shows that it’s possible to protect” the doucs, says Chuong, “if we keep Son Tra pristine.”
Stefan Lovgren is a frequent contributor to National Geographic and covers the Mekong River as part of the USAID project “Wonders of the Mekong.” He is the co-author of Chasing Giants: In Search of the World’s Largest Freshwater Fish.
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