Man-Made Tightrope Bridge Saves Gibbons in China

Scientists assist rare gibbons by installing rope bridges.

Jan 2, 2021
Man-Made Tightrope Bridge Saves Gibbons in China | Scientists assist rare gibbons by installing rope bridges.

Looking way up into the trees, you could glimpse some of the best acrobats on earth swinging from tree to tree. These are rare Hainan gibbons — and thanks to human intervention — their survival is being assisted as they use manmade bridges to get around the rainforest.

Hainan gibbons live exclusively on Hainan Island, off the coast of southern China. With only around 30 left, they are, according to a scientific report published in the journal Nature, one of the most endangered primates in the world. Swinging from tree to tree in the rainforest, they need the canopy to survive and will never set foot on the ground.

However, in 2014, Super Typhoon Rammasun tore across the island, causing landslides that fell trees. With a 50-foot-wide gouge in the forest, the gibbons were imperiled as they were unable to access food. Families members were separated, and their opportunities for finding mated were reduced.

Many of the gibbons were stranded. Unlike monkeys, they do not have tails so when they leap from tree to tree, they have no extra assistance in their swing. After the landslide tore down trees, they were forced to jump across the abyss in what looked like death-defying acts. The male gibbons seemed fine with this new challenge, but the females, some pregnant and others with babies clinging to them, as well as juveniles, were hesitant.

The drop to the ground, should a gibbon miss, is 98 feet, according to New Scientist. Researchers watched with concern, and although no accidents were seen, they realized the gibbons needed outside assistance. 

“It was pretty scary to watch – my heart just popped out of my throat,” Bosco Chan, co-author of the Nature report, told New Scientist.

With the assistance of professional tree climbers, scientists constructed a 50-foot-long arboreal bridge with motion sensor cameras, according to Nature. The team anxiously watched the site, and after 176 days, they were relieved to see the first gibbons trying out the bridge.

They soon realized it was only being used by females and juveniles, and as the gibbons became more comfortable with this crossing, the bridge was used more frequently. The researchers assumed that the larger and stronger males did not use the man-made bridge because they were capable of making the hazardous leap unassisted.

But the researchers were very excited by these results as these gibbons have rarely been documented using such bridges. Conservationists across the world use aerial wildlife crossings, mostly in Australia and South America. A rope bridge has been previously used to help other types of gibbons; one was built to assist them crossing a road in Thailand, while a bamboo rope bridge in India has helped gibbons cross patchy areas in a forest.

This rope bridge is extremely important for protecting Hainan gibbons. Around 70 years ago, there were 2,000 gibbons in the wild and just 20 years later, only 10 were left, the species dwindling to near extinction due to poaching and habitat loss, according to the Hainan Gibbon Conservation Project.

These conservationists are carefully monitoring the gibbon activity and report that the dwindling numbers are finally increasing. The numbers today are threefold higher, and with researchers’ help, they will grow more.

The Hainian Bawangling National Nature Reserve now has an active gibbon highway. Recognizing that this aerial bridge is not a long-term solution, the Nature report said that fast-growing trees have been planted beneath the bridge. And they were sure to plant the gibbons’ most favorite fruit tree, ensuring these special primates have access to only the best!

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Nicole is an editor, blogger and author who has recently left her urban life in order to be more connected with nature. In her spare time, she’s outdoors hiking in the forest, mountain biking or tending to her new permaculture garden.