Emerald peaks soar above the Angry River Valley, deep in the heart of Yunnan, China’s Gaoligong Mountains National Nature Reserve. Under the mountain range’s forest canopy, giant tree rhododendrons stand alongside moss-covered, broad-leafed evergreen trees and thick groves of wiry bamboo. The crack of a machete precedes each step we take. It’s a chilly mid-April morning in 2019 and the morning dew dampens the clothes that cling to our skin.
Suddenly, shrill calls burst from the canopy above, echoing through the forest around us. Leaves rustle and tree branches sway. Cai Zhihong points upward. “We found them!” he says, flashing a toothy grin. “The gibbons are here!”
Cai Zhihong, a forest ranger and part of the Lisu ethnic minority indigenous to this region, spends nearly all his time in the reserve. He began working here almost 30 years ago, preventing poaching and helping scientists collect data on the Gaoligong’s gibbons for less than a dollar a day, then later became an instrumental part of gibbon research and conservation efforts as the most senior ranger. Four years ago, an international team led by Chinese scientist Fan Pengfei announced that it had discovered a new species with the help of Cai Zhihong and other rangers: the Skywalker hoolock gibbon (Hoolock tianxing). Overnight, the creature became one of China’s most endangered species, pushing conservation efforts in Cai Zhihong’s beloved Gaoligong to the forefront of public attention.
Gaoligong Mountains National Nature Reserve, China
The Gaoligong Mountains, at the southeastern extent of the Himalaya, are home to the world’s highest-elevation and highest-latitude tropical rainforests. Mostly situated in China’s southwest Yunnan Province and extending northward into Myanmar, they cradle more than 4,000 plant species, 500 species of birds, and 154 species of mammals. They also sit within the Three Parallel Rivers UNESCO World Heritage Site, China’s most biodiverse region. Scientists believe that Skywalker hoolock gibbons diverged from their nearest relatives about 500,000 years ago when the waters of Myanmar’s Irrawaddy River separated them.
Skywalkers are covered in short fur, nearly jet black on males and beige on females. Unlike other gibbon species, they have thin white eyebrows and darker beards. But, like all gibbons, they have no tail, and instead use their long arms for balance when navigating the treetops.
Their arboreal nature makes gibbons hard to follow and study. They spend their lives high in the trees, using their strong and flexible shoulders to swing through the canopy one arm at a time, a form of movement known as brachiation. They can leap up to 10 meters (33 feet), reaching speeds as fast as a racehorse. The easiest way for scientists to find them is by following their songs, which often last up to 30 minutes and can be heard from more than a mile away.
Cai Zhihong grew up in the Gaoligong hearing gibbon song, and scientists had previously presumed those to the east of the Irrawaddy belonged to Hoolock leucodenys, the eastern hoolock gibbon. Fan Pengfei, who began studying eastern hoolocks in China in 2008, suspected otherwise. Cai Zhihong and other rangers, who follow and study gibbon groups up to 25 days a month, helped gather field observations and fecal samples. Finally, after analyzing years of the morphological and genetic information resulting from that work, Fan Pengfei established Skywalkers as a separate species.
The name derives from an ancient divination written by Confucius, which compares a scholar’s vigor to heaven’s movement, literally “tian xing” (天行) in Chinese. Gibbons were often seen as scholarly symbols in ancient China, so the name Hoolock tianxing, which can also be translated to sky (天) walker (行), pays homage to the Confucian phrase. The news excited scientists and Star Wars fans around the world. Mark Hamill, the actor who played Luke Skywalker in the original cinematic trilogy, even tweeted about it.
But the discovery had a dark side: It meant Skywalker gibbons were the only species of the genus Hoolock within China. Scientists estimate that there are just 106 to 138 left in the country, living in three separate clusters from the Gaoligong to the Yunnan-Myanmar border. These subpopulations are separated by impassable 60- to 100-kilometer stretches of agricultural land and towns devoid of contiguous forest. Within these subpopulations, many family groups and individuals are isolated. This makes it even more difficult for them to interbreed and share genes, further threatening the species’ future.
In 2019, the International Union of Conservation of Nature (IUCN) added the Hoolock tianxing to its Red List as “Endangered” and “Decreasing,” as it had with the two other species in the genus—Hoolook hoolock (listed as “Endangered”) and Hoolock leucodenys (listed as “Vulnerable”)—which are dispersed across India, Bangladesh, and Myanmar. Soon after, the IUCN listed Skywalker gibbons among the world’s 25 most endangered primates.
The story is similar for three other species of gibbons that survive in corners of China’s Hainan, Guangxi, and Yunnan Provinces. Once, they were celebrated and widespread. Their range extended through the gorges of the Yangtze River up into northwestern Gansu Province. Famous Tang Dynasty Poet Li Bai commemorated their calls. Jin Dynasty legends claimed that noble scholars would turn into gibbons, while lowly people would devolve into dust and insects. The remains of a novel but now extinct gibbon genus were discovered buried near the famous Terracotta Warriors, in the tomb of the grandmother of Qin Shi Huang, China’s first emperor.
In a story that has become all too familiar, rapid human population expansion during the Qing Dynasty and the 20th century would eventually destroy the majority of the country’s gibbon habitat. From the 1950s through the 1980s loggers, encouraged by the national forestry bureau, cut 1.5 million hectares (3.7 million acres) of forest, about 37 to 47 percent of China’s total historical loss. Today, all of China’s gibbons face similar threats: cross-border poaching and trade between China and its Southeast Asian neighbors, genetic isolation, and insufficient habitat. For the Skywalker gibbon, one of the main causes of habitat loss is coffee.
French missionaries first brought coffee to Yunnan in the 1800s, but the industry didn’t take off until 1988, when the Chinese government, the United Nations Development Programme, the World Bank, and Nestlé developed an initiative to promote the crop. Today, 125,000 hectares (309,000 acres) of coffee plantations in Yunnan, including in the Gaoligong Mountains, produce more than 95 percent of Chinese coffee.
Glossy-leafed coffee plants now spread to the Gaoligong’s horizon. There is little doubt that coffee development has helped locals. With the aid and investment of large companies like Starbucks, which has put $20 million toward coffee plantation development and poverty alleviation here and elsewhere in Yunnan until 2023, three-quarters of farmers have seen their incomes rise. Yunnan coffee from remote villages like Gangdang now sells for $23 a half-pound bag in the United States.
But this premium comes at a cost for the Hoolock tianxing. Studies in Myanmar have shown that Skywalkers prefer habitat from 250 to 5,000 feet elevation, precisely where Yunnan coffee is grown on the Gaoligong. Above 5,000 feet, the coffee ends abruptly as it meets the national nature reserve’s border. Inside, the gibbons make do with colder, suboptimal habitat with lower carrying capacities.
Within the reserve, tsaoko (Fructus tsaoko), a densely growing plant whose dried fruit is also known as black cardamom—a staple spice in a favorite Chinese cuisine known as hotpot—encroaches further on Skywalker gibbon habitat. Farmers have grown tsaoko as a cash crop in Yunnan since the 1980s, spurred by yet more efforts to alleviate poverty. The government contracted plots of land within the nature reserve to locals to grow tsaoko, because it was a linxia zhongzhi, a term for agricultural projects viewed as compatible with forests’ ecological integrity.
Then in 2014, scientists published a study that revealed tsaoko growth was responsible for over half the decrease in Yunnan’s gibbon populations. The researchers found that growing tsaoko under the forest canopy led to the removal of many of the tallest trees in order to increase sunlight penetration on the forest floor. This reduced the gibbon’s food choices and sleeping sites, while making travel more energetically costly and dangerous.
Today, tsaoko is the primary source of income for many households around the Gaoligong. For some villages bordering Hoolock tianxing habitat, it accounts for up to 90 percent of local earnings. Now, according to Yan Lu, the founder of local NGO Cloud Mountain Conservation, which specializes in gibbon conservation in China, the government is looking for ways to phase out the crop as contracts expire. But the process isn’t easy. “If the nature reserve just directly removes the tsaoko fields after the contracts, this will also create conflict,” Yan Lu says.
Cloud Mountain Conservation is trying to ease the transition by helping farmers diversify their crops, which can also help protect them from dramatic market fluctuations. In 2017–2018, the price of tsaoko ran around $16 per pound. In 2019, the price dropped by half. Yan Lu hopes that by encouraging farmers to grow traditional medicinal herbs and vegetables that thrive at the foot of large trees, her organization can ensure that both gibbons and local farmers have a more stable future.
Cross-border Forest Loss
While China harvested some 1.5 million hectares (3.7 million acres) of its forests between the late 50s and early 80s, those forests have begun to regrow in recent decades. In contrast, Myanmar’s forests have been decimated in recent years, putting Skywalker gibbons there under serious threat.
But that future faces another serious threat: poaching, which has deep roots in Chinese traditional medicine and the desire for culinary yewei, or “wild flavor.” Many locals around the Gaoligong traditionally regard gibbon brain as a cure for headaches and child epilepsy. Despite the efforts of Cai Zhihong and other rangers to stop poachers, dried skulls can often be seen for sale in local markets. Throughout the last decade, news stories of live gibbons being sold via Chinese social platforms WeChat and Weibo and in pet markets have circulated online. Scientists warn that such practices increase the risk of transmitting viruses to humans, not to mention the toll they take on dwindling gibbon populations.
As much as some local beliefs about gibbons threaten the species’ future, though, in areas outside nature reserves they may also hold the key to securing it. Many local Lisu living around one of the three gibbon clusters in Yunnan do not hunt gibbons because their culture maintains strong generational taboos against the practice. They believe gibbons are primate gods that can forecast the weather or even death through their singing, and that killing gibbons can bring misfortune to a hunter’s family or whole village. A group of scientists, including Fan Pengfei, argued last year that this kind of traditional ecological knowledge is an indispensable complement to conservation measures and enforcement.
A deep, experiential understanding of the local environment makes rangers like Cai Zhihong all the more important. “He is not just a treasure trove of local plant, animal, and natural history knowledge,” says Yan Lu, “but he is also the most trusted guide to conservationists and scientists.”
Chang Yue, another conservationist working with Cloud Mountain Conservation who frequently lives in the Gaoligong and patrols with Cai Zhihong, believes that research would be impossible without him. “Cai Zhihong is one of the people in China who most understands Skywalker gibbons in the wild,” she told me.
In other places where Lisu culture and reliance on traditional ecological knowledge are not as prominent, China’s gun ban and the efforts of local rangers and NGOs have gradually reduced poaching. In the Tengchong section of the Gaoligong bordering Myanmar, Hong Kong–based NGO Kadoorie Farm and Botanic Garden (KFBG) has been working to study and protect the gibbons since 2014. Yang Jianhuan, a senior conservation officer with KFBG, has been leading an extensive survey on local people’s relationship with the Hoolock tianxing. When he asked locals if their family grew up hunting gibbons, half replied, “Of course they did.” Now, Yang Jianhuan says, most “know that the gibbons are strictly protected in China so they would not touch them.”
Still, Yang Jianhuan believes poaching remains the biggest threat to Skywalkers on the Yunnan-Myanmar border. While Chinese hunters are fewer due to strict laws, locals frequently report poachers from Myanmar secretly crossing the unguarded border to hunt gibbons in China.
Little is known about the status of the Skywalker gibbon in Myanmar. At last count, seven years ago, the IUCN listed the population size between 10,000 and 50,000 individuals, but noted that deforestation and lack of protected areas could halve that in just 25 years. Political unrest has prevented scientists from further investigation since.
So it is that, for conservationists like Yang Jianhuan and Yan Lu, the greatest opportunities to study Hoolock tianxing and ensure its future remain inside China. A variety of actions have been proposed to halt the Skywalkers’ decline there. To connect isolated individuals and family groups, the local government hopes to create a captive breeding and reintroduction program. But there aren’t enough Skywalker hoolocks in captivity to start such a program, so officials would need to capture wild gibbons, and Yan Lu worries that there may not be enough remaining to justify the risk of harming them in the process. Though the Gaoligong National Nature Reserve has recommended this plan to officials in Beijing, they are still awaiting a response.
For the time being, Yan Lu believes the best hope for Hoolock tianxing in China is continued habitat restoration and a decrease in human disturbance. Eastern hoolocks in Myanmar mate every two years, much quicker than the Skywalkers in China, which average once every three to five years. Yan Lu believes that if habitat quality were improved, the reproductive rate among Skywalker gibbons in China would increase. She also proposes constructing aerial crossings between disconnected canopies—a model that recently proved effective for Hainan gibbons, a species and conservation effort featured in bioGraphic’s story “The Gibbon’s Tail.”
KFBG is currently developing a report recommending the local government create a new nature reserve to protect six Skywalker gibbon groups outside the Gaoligong National Nature Reserve. Yang Jianhuan says it’s hard to know how long this could take. In 2009, Guangxi Province created a special protected area dedicated to the eastern black crested gibbon (Nomascus nasutus) following its discovery in China three years earlier. If a similar area could be created to protect the remaining Skywalker gibbons outside the Gaoligong National Nature Reserve, Yang Jianhuan believes it would be a big step toward guarding their future.
“The government now views gibbon protection as very important, so I am optimistic for gibbon conservation in China, because more NGOs like us and Cloud Mountain Conservation are increasing efforts aimed at conserving the gibbons,” Yang Jianhuan told me.
Of course, the day-to-day work of tracking, monitoring, and protecting the gibbons still falls to rangers like Cai Zhihong, who also remains optimistic. And at the end of 2020, after hearing an unfamiliar gibbon song, he would go on to discover and document an unknown group of Skywalkers in the same valley that he explores with me now.
Cai Zhihong and I follow the pair of gibbons up the mountainside, digging our toes into the mud and grasping at roots to lever ourselves upward. Above, the gibbons propel themselves through the trees in an effortless display as captivating as their song.
The glow in Cai Zhihong’s eyes sharpens as we come to a boulder perched atop an open ridge. The valleys of the Gaoligong spill out below, disappearing into the haze overhanging the Angry River. We sit down to rest and take in a rare view unobstructed by the canopy. For the first time, I see two waterfalls tumbling below, and Cai Zhihong points downstream, showing me the way to his home.
The gibbons’ song, barely audible now, seems as inseparable from this landscape as the distant rumble of the falls and the rhododendron-scented breeze on our necks.
Cai Zhihong tells me, without glancing over, that even after all these years he hasn’t tired of views like this. Even on his days off back home in the village, he says, “My body is sleeping, but my heart is still up in the Gaoligong.”
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Kyle Obermann is a Mandarin-and English-speaking environmental photographer based in China. His work focuses on promoting stories of Indigenous conservation groups protecting China’s last great wildernesses. He is also a The North Face sponsored ultra-marathoner and explorer, as well as the founder of Explore To Conserve, a movement dedicated to connecting China’s outdoor industry and environmental movement. His work has been published in Chinese and English language adventure and conservation publications around the world. Follow his work on Instagram @kyleobermann or at kyleobermannphotography.com.