For the first time, a critically endangered Sumatran orangutan has been filmed using a canopy bridge to cross a public road. The breakthrough comes after two years of monitoring camera-trap footage by conservationists.
A Lifeline Over the Lagan-Pagindar Road
In 2024, the Sumatran Orangutan Society (SOS) and its local partner, Tangguh Hutan Khatulistiwa (TaHuKah), installed a high bridge over the Lagan-Pagindar road. The bridge is located in the Pakpak Bharat district of North Sumatra in Indonesia.
While the road serves as an essential route for local residents, Erwin Alamsyah Siregar, director of TaHuKah, noted that natural crossing had become “impossible for wildlife.” The structure was built with assistance from the local government to restore connectivity.
Preventing Functional Extinction
The road previously split a population of 350 orangutans into two isolated groups. One group was sequestered at the Siranggas wildlife reserve, while the other remained in the Sikulaping protection forest.
Helen Buckland, chief executive of SOS, explained that orangutans are prone to genetic bottlenecks due to their slow life history. Without the ability to mingle, slight groups could be weakened by inbreeding, potentially leading to functional extinction.
The First Crossing
The footage captures a young male orangutan edging onto the bridge. Halfway across, the animal paused to look at the road below and the camera before continuing into the Sikulaping protection forest.
Other species had already begun utilizing the bridge, including agile gibbons, long-tailed macaques and black giant squirrels. However, the orangutan’s crossing is a significant milestone for the 14,000 Sumatran orangutans remaining in the wild.
Potential Future Implications
The successful use of the bridge may encourage other orangutans in the area to establish new mental maps of the route. If more individuals utilize the crossing, it could potentially mitigate the risk of genetic bottlenecks for the local population.
This outcome may serve as a model for other regions where roads bisect critical habitats, suggesting that similar canopy bridges could be a viable method for protecting threatened arboreal mammals.
Frequently Asked Questions
Where is the canopy bridge located?
The bridge is located over the Lagan-Pagindar road in the Pakpak Bharat district of North Sumatra, Indonesia.
Why is the bridge important for the Sumatran orangutan?
The bridge allows orangutans to cross a road that split their population between the Siranggas wildlife reserve and the Sikulaping protection forest, reducing the risk of inbreeding and functional extinction.
What other animals have used the bridge?
Before the orangutan was filmed, the bridge was used by agile gibbons, long-tailed macaques, and black giant squirrels.
Do you believe similar wildlife bridges should be mandatory for all roads passing through protected forests?
