Orangutans (Pongo spp.) Fact Sheet: Population & Conservation Status

Bornean orangutans (Pongo pygmaeus)

• Not precisely known (IUCN)
  • 55,000-104,000 individuals
    • Loss of 50% of historic population in only 40 years
• Between 1996 and 1997 the population dropped by 33% due to fires and drought (Rijksen & Meijaard 1999) (Delgado & Van Schaik 2000)
• Estimates obtained between 2000 and 2003 indicate between 45,000 and 69,000 individuals, but rapidly declining since then (Singleton et al. 2004)
• Populations on Borneo possibly have "lower mortality, faster breeding, more capacity for rapid population growth" when compared to those of Sumatran orangutans (Singleton et al. 2004)
• Habitats need to support populations of at least 250 individuals to allow genetic stability and stable populations (Singleton et al. 2004)
• Rates of hunting over 3% a year will drive any population to extinction, even in good habitats (Singleton et al. 2004)

Sumatran Orangutans (Pongo abelii)

• Population is much smaller than that in Borneo, approximately 14,000 individuals (IUCN)
• Experienced a population decline of over 80% in the last 75 years (Singleton et al. 2008)
• Population in 2000 estimated at 12,500 individuals; approximately 14% of the estimated population from 1900.
• According to the IUCN SSC Conservation Breeding Specialist Group (Singleton et al. 2004) "populations may decline by 50% in about a decade, by 97% in 50 years, and will eventually disappear unless continued habitat loss is stopped"

Tapanuli Orangutans (Pongo tapanuliensis)
(Narter et al. 2017)

• Fewer than 800 individuals in the wild
• Of high conservation concern
  • Small population size
  • Geographically isolated

IUCN

• Sumatran Orangutan (Pongo abelii)
  • Critically Endangered (2017 assessment) (Singleton et al. 2017)
• Bornean Orangutan (Pongo pygmaeus)
  • Critically Endangered (2016 assessment) (Ancrenaz et al. 2016)
• Tapanuli Orangutan (Pongo tapanuliensis)
  • Critically Endangered (2017 assessment) (Nowak et al. 2017)

CITES

• Pongo abelii: Appendix I (UNEP 2019)
• ​Pongo pygmaeus: Appendix I (UNEP 2019)
• Pongo tapanuliensis: Not listed (UNEP 2019)​

Other protections

• Protected under some domestic legislations in Indonesia

Habitat loss and fragmentation

• Orangutans' arboreal lifestyle makes them extremely vulnerable to habitat fragmentation and tree loss
• Borneo and Sumatra: logging, clearing for cash crops, human population pressure, fires, drought
• In Sumatra, an estimated 1,000 orangutans were lost because of forest loss each year in the 1990's;
• In Sumatra, new political stability since 2005 has allowed many new logging and palm oil concessions (Singleton 2008)

Hunting by humans

• For the pet trade and for food

Political unrest

• Disturbance, loss of habitat
• Difficult to implement conservation strategies

Other notes

• Slow reproductive rate makes the orangutan more vulnerable to long-term disturbance

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Delgado & Van Schaik (2000)
Hutchins, et al., (2001)
Rijksen & Meijaard (1999)
Rijksen, (2001)
Singleton et al., (2004)
Singleton et al, (2008)