Over a 16-year period, about half of the orangutans living on the island of Borneo were lost as a result of changes in land cover. That’s according to estimates reported in Current Biology on February 15 showing that more than 100,000 of the island’s orangutans disappeared between 1999 and 2015.
Many of those losses were apparently driven by the demand for logging, oil palm, mining, paper, and associated deforestation. However, many orangutans have also disappeared from more intact, forested areas, the researchers say. Those findings suggest that hunting and other direct conflicts between orangutans and people remain a major threat to the species.
“The decline in population density was most severe in areas that were deforested or transformed for industrial agriculture, as orangutans struggle to live outside forest areas,” says Maria Voigt of the Max Planck Institute for Evolutionary Anthropology in Germany. “Worryingly, however, the largest number of orangutans were lost from areas that remained forested during the study period. This implies a large role of killing.”
Maria Voigt, Serge A. Wich, Marc Ancrenaz, Erik Meijaard, Nicola Abram, Graham L. Banes, Gail Campbell-Smith, Laura J. d’Arcy, Roberto A. Delgado, Andi Erman, David Gaveau, Benoit Goossens, Stefanie Heinicke, Max Houghton, Simon J. Husson, Ashley Leiman, Karmele Llano Sanchez, Niel Makinuddin, Andrew J. Marshall, Ari Meididit, Jukka Miettinen, Roger Mundry, Musnanda, Nardiyono, Anton Nurcahyo, Kisar Odom, Adventus Panda, Didik Prasetyo, Aldrianto Priadjati, Purnomo, Andjar Rafiastanto, Anne E. Russon, Truly Santika, Jamartin Sihite, Stephanie Spehar, Matthew Struebig, Enrique Sulbaran-Romero, Albertus Tjiu, Jessie Wells, Kerrie A. Wilson, Hjalmar S. Kühl. Global Demand for Natural Resources Eliminated More Than 100,000 Bornean Orangutans. Current Biology, 2018; DOI: 10.1016/j.cub.2018.01.053