In a thrilling development for anyone who has ever rooted for a slow-moving primate, a critically endangered Sumatran orangutan has been filmed for the first time using a canopy bridge to cross a road in North Sumatra.
The bridge was built in 2024 by conservationists from the Sumatran Orangutan Society (SOS) and its local partner Tangguh Hutan Khatulistiwa (TaHuKah) over the Lagan-Pagindar road in the Pakpak Bharat district. The road is essential for local people but was an impassable barrier for wildlife. “Natural crossing was impossible for wildlife,” said Erwin Alamsyah Siregar, director of TaHuKah.
For two years, the team watched camera-trap footage of the bridge, waiting for an orangutan to take the plunge - or rather, the climb. “You should have heard the cries of delight from the team,” said Helen Buckland, chief executive of SOS. “After two long years, it’s finally happened.”
The young male orangutan is seen edging onto the bridge, pausing halfway to look down at the road below, then back at the camera, before proceeding into the Sikulaping protection forest. It’s a slow, deliberate crossing that gives new meaning to the phrase “look both ways.”
For the 350 orangutans in the area, the road had split them into two populations, one at the Siranggas wildlife reserve and the other at the Sikulaping protection forest. Orangutans, the largest arboreal mammals, spend more than 90% of their time in the forest canopy and are a keystone species. They have excellent memories and can make mental maps of new routes - though apparently it takes them two years to update their GPS.
“Orangutans have a very slow life history, and are really prone to genetic bottlenecks,” said Buckland. If kept in small groups, they weaken from inbreeding until they are functionally extinct: surviving for now but heading toward long-term oblivion. The bridge offers a glimmer of hope that this population won’t become a cautionary tale.
Other species had already taken to the bridge - black giant squirrels, long-tailed macaques, agile gibbons - but orangutans held out. Now, finally, one has shown that it’s not too proud to use infrastructure built by humans.
There are only 14,000 Sumatran orangutans left in the wild, making them one of the world’s most threatened apes. Franc Bernhard Tumanggor, head of the Pakpak Bharat district, said: “Witnessing a Sumatran orangutan confidently crossing that bridge is living proof that we need not sever the forest’s lifeline in order to build our communities’ own. Modernisation does not have to mean destruction.”