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Line 3: + − + − − Bornean orangutans lead a predominantly solitary existence, seldom congregating in groups. Males, as the dispersing sex, depart from their birthplaces upon attaining sexual maturity (typically at 10–12 years old) to establish expansive territories spanning several hundred hectares. Female territories are comparatively smaller, their actual size influenced by forest composition and food resource availability. These orangutans reproduce at a slow pace, typically giving birth to one offspring every 6–8 years, a factor contributing to their heightened vulnerability to hunting pressures. Female sexual maturity is attained at 10–15 years old (Kingsley 1981). Line 28:
Line 27: − Ancrenaz, M., Sollmann, R., Meijaard, E., Hearn, A. J., Ross, J., Samejima, H., ... & Wilting, A. (2014). Coming down from the trees: Is terrestrial activity in Bornean orangutans natural or disturbance driven?. Scientific reports, 4(1), 4024.<br> Line 34:
Line 32: − Kingsley, S. (1981). The reproductive physiology and behavior of captive orangutans (Pongo pygmaeus). University of London.<br> − +
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'''Population status'''<br>
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.
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.
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.
Bornean orangutans hold the distinction of being the largest arboreal mammals globally, although they can also walk long distances on the ground (Ancrenaz et al. 2014).
The population trend for all subspecies of Bornean orangutans is decreasing (Voigt et al. 2018).
'''References'''<br>
'''References'''<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
Sabah Wildlife Department (2020). Orangutan Action Plan for Sabah 2020-2029. Kota Kinabalu, Sabah, Malaysia.<br>
Sabah Wildlife Department (2020). Orangutan Action Plan for Sabah 2020-2029. Kota Kinabalu, Sabah, Malaysia.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>
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.<br>