JAKARTA — The number of Sumatran orangutans has declined by nearly 20% in the past decade and the critically endangered Tapanuli orangutan remains perilously close to extinction despite years of conservation efforts, according to a new study. The study, published in Global Ecology and Conservation, also suggests that habitat loss alone cannot explain the species’ decline. While deforestation remains the primary driver, several orangutan populations in Indonesia’s island of Sumatra shrank by a far greater degree than the rate of forest loss might explain, pointing to additional threats such as killing, conflict with humans and habitat fragmentation. The findings come from the first comprehensive reassessment of both Sumatran (Pongo abelii) and Tapanuli (Pongo tapanuliensis) orangutans since the landmark 2016 range-wide survey led by primatologist Serge Wich. The study also signals a notable shift in the Indonesian government’s public approach to orangutan conservation. Between 2018 and 2022, then environment and forestry minister Siti Nurbaya Bakar repeatedly said “ground-based evidence” showed orangutan populations were growing and dismissed projections of continued decline. Those claims were challenged at the time by prominent primatologists, who argued that peer-reviewed research consistently showed that the populations of all three orangutan species, Sumatran, Tapanuli and Bornean (Pongo pygmaeus), were declining and urged the ministry to release the data underpinning its assertions. The dispute escalated when the ministry temporarily barred several of the scientists from conducting research with Indonesia’s national parks and conservation agencies. The latest assessment of the animals presents a picture that’s markedly different from the previous…This article was originally published on Mongabay

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