PREVIEW

Conservationists have new hope for the future of Sumatran orangutans after filming the first known footage of using a rope bridge to cross a road.

The video, captured by a camera trap in the Pakpak Bharat district of North Sumatra, shows a young male orangutan carefully climbing onto a rope bridge and making its way high above the traffic below.

Conservationists say the moment confirms that the critically endangered Sumatran orangutan is willing to use such structures to navigate fragmented forest habitats.

While similar bridges have previously been used by primates including gibbons and langurs, this is the first recorded instance involving orangutans.

The Lagan–Pagindar road, which provides vital access to schools, hospitals, and other services for remote communities, has also created a barrier for wildlife.

Around 350 orangutans are thought to live in the area, split between the Siranggas Wildlife Reserve and the Sikulaping Protection Forest.

Erwin Alamsyah Siregar, executive director of TaHuKah, said: “The construction of the Lagan-Pagindar road provided essential infrastructure for local families, giving them access to healthcare and education. However, upgrades in 2023 widened the gap in the canopy, making natural crossings impossible for wildlife.”

Without a way to cross, conservationists warn the isolated population risks becoming trapped in a genetic bottleneck, increasing the likelihood of inbreeding and long-term decline.

To address this, five canopy bridges were installed along the road in 2024, designed to reconnect the forest and allow animals to move safely between habitats.

Helen Buckland, chief executive of UK-based charity the Sumatran Orangutan Society, who have co-led the project, said: “For two years, we have watched and waited for this moment. Seeing this young male orangutan confidently cross the road using the canopy bridges is a huge milestone for conservation – proving that it is possible to stitch this fragmented landscape back together. These bridges are a practical, effective and scalable intervention for developing regions, where essential infrastructure disrupts wildlife corridors.”

The rope bridge building was carried out in collaboration with local government and environmental authorities.

Each bridge, constructed from around 200 metres of rope, took several days to install and was stress-tested to support multiple adult orangutans.

Different designs - including single-rope, ladder and hybrid bridges - were used to suit a range of species. Camera traps have been monitoring activity, with regular inspections carried out to assess wear and tear.

Before the orangutan sighting, the bridges were already being used by species such as squirrels, long-tailed macaques, langurs and gibbons.

Orangutans are considered a keystone species, spending most of their lives in the forest canopy and playing a crucial role in maintaining ecosystem health.

Often referred to as “gardeners of the forest”, they disperse seeds over large distances and help regenerate woodland.

Conservationists warn that their loss could have far-reaching consequences, affecting not only biodiversity but also the natural resources on which local communities depend.

Efforts to protect orangutans also help safeguard other threatened wildlife in the region, including Sumatran tiger, sun bears and clouded leopards, supporting the wider ecosystem.