Arboreal Bridges Proposed to Save Critically Endangered Tapanuli Orangutan

A new initiative is being considered in the Batang Toru rainforest of North Sumatra, Indonesia, to protect the critically endangered Tapanuli orangutan (Pongo tapanuliensis). The Yayasan Ekosistem Lestari (YEL) is proposing the construction of "arboreal bridges" to overcome habitat fragmentation and maintain genetic diversity. Batang Toru is the sole habitat for the Tapanuli orangutan, one of the world's most endangered primates. However, its habitat has been rapidly shrinking in recent years due to infrastructure development and changes in land use. According to YEL data, forest cover in the ecological corridor of the Hutaimbaru area has decreased from 9,958.38 hectares in 2004 to 8,980.84 hectares in 2024. This amounts to a loss of over 1,700 hectares of habitat in the last two decades. This forest loss has a severe impact on the survival of the Tapanuli orangutan. The corridor connecting the eastern and western parts of Hutaimbaru is particularly crucial for maintaining gene flow between populations. Fragmentation of this corridor increases the risk of local extinction. A disaster in 2025 further exacerbated the situation, leading to the degradation of 23.30 hectares of cleared land and 22.70 hectares of buffer zones. Julius Paolo Siregar, Head of YEL's InSitu Conservation Division, stated, "Our main goal is to restore connectivity between the western and eastern blocks so that the corridor can function optimally." He emphasized that for every hectare of forest lost, the survival chances of the Tapanuli orangutan diminish. While an arboretum has been established, it has not yet achieved adequate canopy cover, making the rehabilitation and restoration of the area urgent. The construction of arboreal bridges is being considered as an important option when natural corridors are insufficient to bridge open spaces. Siregar highlighted the need for mapping and analyzing the connecting paths between the eastern and western regions, based on scientific evidence, to restore the corridor's functionality. The construction of arboreal bridges, land restoration, and collaborative corridor management are concrete steps that need strengthening before this iconic species becomes permanently extinct. Source: Mongabay Indonesia