Northeast Bornean Orangutan

Range countries
Malaysia, Indonesia

Population status
Northeast Bornean orangutans (Pongo pygmaeus morio) are native to the island of Borneo, inhabiting the Malaysian states of Sabah and Sarawak, as well as two of the Indonesian Provinces of Kalimantan: North and East Kalimantan. Most of the remaining population of Northeast Bornean orangutans is concentrated in Sabah and East Kalimantan, with small scattered groups also present in North Kalimantan.

It has been estimated that fewer than 20,000 Northeast Bornean orangutans remain (Ancrenaz et al. 2016). In Kalimantan, the majority of P. p. morio populations are situated outside protected areas, in forests that have been set aside for conversion to other land uses (Wich et al. 2012). In Sabah, although approximately 80% of orangutans reside in protected forests, numerous populations continue to decline due to ongoing land conversion, hunting, and forest fragmentation. Recent research suggests a 25% decline in the orangutan population within Sabah over the past decade alone (Santika et al. 2017). Overall, more than 86% of this subspecies is anticipated to vanish within three generations (1950–2025), leading to its classification as Critically Endangered on the IUCN Red List of Threatened Species. The population trend for all subspecies of Bornean orangutans is decreasing (Voigt et al. 2018).

Threats
The main threats to Northeast Bornean orangutans are habitat loss, illegal hunting, fires, habitat fragmentation, and increasingly, climate change (Ancrenaz et al. 2016). In Sabah, genetic studies indicate that over the past two centuries, human activities have led to the loss of more than 90% of the original orangutan population (Goossens et al. 2006). The state of Sabah has witnessed the highest rate of forest loss in Borneo, with a 39.5% decrease in forest cover from 1973 to 2010, primarily affecting the eastern lowland forests, a favored orangutan habitat (Gaveau et al. 2014).

In Kalimantan, orangutan populations face similar threats, including hunting pressure, forest fires, and conversion of forests to agricultural land. Areas in East Kalimantan inhabited by orangutans exhibit a high risk of conflict, largely driven by rapid conversion of natural land cover to plantations. The subspecies is rapidly decreasing, with climate change and land-use alterations expected to exacerbate habitat loss (Struebig et al. 2015). Fires have also significantly contributed to declines; for instance, Kutai National Park lost 90% of its area to extensive fires in 1983 and 1998, resulting in a drastic reduction of the orangutan population from around 4,000 individuals in the 1970s to a mere 600 (Rijksen and Meijaard 1999, Wich et al. 2009).

The illegal killing of Northeast Bornean orangutans is also a main contributor to their population decline. Interview surveys conducted in Kalimantan have unveiled that several thousand individuals are slaughtered annually for purposes such as meat consumption, conflict mitigation, or other motives (Davis et al. 2013). Overall mortality rates for Bornean Orangutans in Kalimantan appear to far surpass the maximum sustainable rates for this species, known for its slow reproductive rate (Marshall et al. 2009, Meijaard et al. 2011).

Conservation Activities
The Northeast Bornean Orangutan benefits from full protection in Malaysia and Indonesia, listed on Appendix I of CITES. However, its forest habitat lacks comprehensive protection, with approximately 20% of the current orangutan range in Sabah and 80% in Kalimantan remaining unprotected (Wich et al. 2012). Urgent innovative strategies are required to ensure the long-term survival of Bornean orangutans outside protected forests.

The fate of Bornean orangutans heavily relies on the enduring security of extensive, strictly protected forests where illegal logging and hunting can be effectively managed, and orangutan populations can withstand catastrophic events like fires and disease outbreaks (Meijaard et al. 2011). These forests should encompass ecological gradients that provide essential resources to sustain orangutans amidst climate and other gradual environmental changes (Gregory et al. 2012). At a broader landscape scale, scientifically informed regional land-use planning is imperative to delineate interaction zones around protected forests and their environs, considering hydrological, ecological, and socio-economic dynamics. Ideally, core protected areas should remain connected to other forested regions suitable for sustainable (commercial) timber extraction. The formulation of such integrated landscapes demands a comprehensive approach spanning the entire landscape, rather than focusing solely on individual sites; this is a focal point of the Orangutan Action Plan for Sabah, which covers a ten year period, from 2020-2029 (SWD 2020).

References
Ancrenaz, M., Gumal, M., Marshall, A.J., Meijaard, E., Wich , S.A. & Husson, S. (2016). Pongo pygmaeus ssp. morio. The IUCN Red List of Threatened Species 2016: e.T63544A17990681. https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T63544A17990681.en. Accessed on 26 January 2024.
Davis, J.T., Mengersen, K., Abram, N., Ancrenaz, M., Wells, J., & Meijaard, E. (2013). It’s not just conflict that motivates killing of orangutans. PLoS One, 8(10), e75373.
Gaveau D.L.A., Sloan S., Molidena E., Yaen H., Sheil D., Abram N.K., Ancrenaz M., Nasi R., Quinones M., Wielaard N., & Meijaard E. (2014). Four decades of forest persistence, loss and logging on Borneo. PLoS One, 9(7), e101654.
Goossens, B., Chikhi, L., Ancrenaz, M., Lackman-Ancrenaz, I., Andau, P., & Bruford, M.W. (2006). Genetic signature of anthropogenic population collapse in orang-utans. PLoS Biology, 4, e285–e291.
Gregory, S.D., Brook, B.W., Goossens, B., Ancrenaz, M., Alfred, R., Ambu, L.N., & Fordham, D.A. (2012). Long-term field data and climate-habitat models show that orangutan persistence depends on effective forest management and greenhouse gas mitigation. PLoS One, 7(9), e43846.
Marshall, A.J., Lacy, R., Ancrenaz, M., Byers, O., Husson S.J., Leighton, M., Meijaard, E., Rosen, N., Singleton, I., Stephens, S., Traylor-Holzer, K., Utami Atmoko, S.S., van Schaik, C.P., & Wich, S.A. (2009). Orangutan population biology, life history, and conservation. In: S.A. Wich, S.S. Utami Atmoko, T. Mitra Setia and C.P. van Schaik (eds), Orangutans: Geographic Variation in Behavioral Ecology and Conservation, pp. 311–326. Oxford University Press, Oxford, UK.
Meijaard, E., Buchori, D., Hadiprakarsa, Y., Ancrenaz, M., et al. (2011). Quantifying killing of orangutans and human-orangutan conflict in Kalimantan, Indonesia. PLoS One, 6(11), e27491.
Rijksen, H.D. and Meijaard, E. (1999). Our Vanishing Relative: The Status of Wild Orangutans at the Close of the Twentieth Century. Kluwer, Dordrecht, The Netherlands.
Sabah Wildlife Department (2020). Orangutan Action Plan for Sabah 2020-2029. Kota Kinabalu, Sabah, Malaysia.
Santika, T., Ancrenaz, M., Wilson, K. A., Spehar, S., Abram, N., Banes, G. L., ... & Meijaard, E. (2017). First integrative trend analysis for a great ape species in Borneo. Scientific Reports, 7(1), 4839.
Struebig, M.J., Fischer, M., Gaveau, D.L.A., Meijaard, E., Wich, S.A., Gonner, C., Sykes, R., Wilting, A., & Kramer-Schadt, S. (2015). Anticipated climate and land-cover changes reveal refuge areas for Borneo's orang‐utans. Global Change Biology, 21, 2891–2904.
Voigt, M., Wich, S. A., Ancrenaz, M., Meijaard, E., Abram, N., Banes, G. L., ... & Kühl, H. S. (2018). Global demand for natural resources eliminated more than 100,000 Bornean orangutans. Current Biology, 28(5), 761-769.
Wich, S. A., Gaveau, D., Abram, N., Ancrenaz, M., Baccini, A., Brend, S., ... & Meijaard, E. (2012). Understanding the impacts of land-use policies on a threatened species: is there a future for the Bornean orang-utan?. PloS one, 7(11), e49142.
Wich, S.A., de Vries, H., Ancrenaz, M., Perkins, L., Shumaker, R.W., Suzuki A., & van Schaik, C.P. (2009). Orangutan life history variation. In: S.A. Wich, S.S. Utami Atmoko, T. Mitra Setia and C.P. van Schaik (eds), Orangutans: Geographic Variation in Behavioral Ecology and Conservation, pp. 65–75. Oxford University Press, Oxford, UK.

Last updated January 2024