Saving the critically endangered Bornean orangutan

A Bornean orangutan asleep in a tree

Bornean orangutan populations have declined by 25% over the last 10 years: Professor Serge Wich explains what action is being taken

The Bornean orangutan is one of only two great ape species found in Asia and according to the IUCN Red list is critically endangered. There is currently no accurate rate of decline and no detailed analysis of the drivers of decline. We have produced the first integrative trend analysis for a great ape species in Borneo with results recently published in Scientific Reports.

This study used a new approach that overcame some of the methodical challenges that come with determining populations. It has now provided an underlying population trend through time. We used a dynamic population model that has allowed the abundance and distribution of the Bornean orangutan to be assessed over time.

The research has not only found a more accurate estimate of decline but has analysed the possible causes of such decline. The orangutan lives in lowland natural forests with high levels of rainfall: this creates the perfect environment for wild tropical fruit, an important component of their diet. These areas are also the best for agricultural productivity, creating a clear conflict between the orangutans and the human population. The main anthropogenic causes of decline are habitat loss and fragmentation due to deforestation, killing due to human-orangutan conflict and hunting for food or at the edge of the forest and agriculture during human-orangutan conflicts. Climate change is intensifying these problems, as indicated by earlier studies.

Read the full report at and find out more about courses and the research undertaken in the School of Natural Sciences and Psychology.


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