The World's 25 Most Endangered Primates

The World's 25 Most Endangered Primates is a list of highly endangered primate species selected and published by the International Union for Conservation of Nature Species Survival Commission Primate Specialist Group, the International Primatological Society, Global Wildlife Conservation, and Bristol Zoological Society. The IUCN/SSC PSG worked with Conservation International to start the list in 2000, but in 2002, during the 19th Congress of the International Primatological Society, primatologists reviewed and debated the list, resulting in the 2002–2004 revision and the endorsement of the IPS. The publication was a joint project between the three conservation organizations until the 2012–2014 list when BZS was added as a publisher. The 2018–2020 list was the first time Conservation International was not among the publishers, replaced instead by GWC. The list has been revised every two years following the biannual Congress of the IPS. Starting with the 2004–2006 report, the title changed to "Primates in Peril: The World's 25 Most Endangered Primates". That same year, the list began to provide information about each species, including their conservation status and the threats they face in the wild. The species text is written in collaboration with experts from the field, with 60 people contributing to the 2006–2008 report and 85 people contributing to the 2008–2010 report. The 2004–2006 and 2006–2008 reports were published in the IUCN/SSC PSG journal Primate Conservation,, since then they have been published as independent publications.
The 25 species on the 2018–2020 list are distributed between 32 countries. The country with the most species on the list is Madagascar with five species, Indonesia, Brazil, Ghana, and Côte d'Ivoire each have three. The list is broken into four distinct regions: the island of Madagascar, the continent of Africa, the continent of Asia including the islands of Indonesia, and the Neotropics.
The purpose of the list, according to Russell Mittermeier, the president of CI, is "to highlight those that are most at risk, to attract the attention of the public, to stimulate national governments to do more, and especially to find the resources to implement desperately needed conservation measures." Species are selected for the list based on two primary reasons: extremely small population sizes and very rapid drops in numbers. These reasons are heavily influenced by habitat loss and hunting, the two greatest threats primates face. More specifically, threats listed in the report include deforestation due to slash-and-burn agriculture, clearing for pasture or farmland, charcoal production, firewood production, illegal logging, selective logging, mining, land development, and cash crop production; forest fragmentation; small population sizes; live capture for the exotic pet trade; and hunting for bushmeat and traditional medicine. Twelve species were dropped for the 2018–2020 list, Mittermeier notes this was not because their situation has improved but instead to focus attention on other species that are also have "bleak prospects for their survival.

Current list

Species	Years listed	Location	Estimated population	IUCN status	Threats
Bemanasy mouse lemur Microcebus manitatra	2018	Madagascar	unknown		loss of habitat
Lac Alaotra bamboo lemur Hapalemur alaotrensis	2000 2014 2016 2018	Madagascar	2,500		loss of habitat live capture
James' sportive lemur Lepilemur jamesorum	2016 2018	Madagascar	1,386		habitat loss hunting live capture
Indri Indri indri	2012 2018	Madagascar	unknown		loss of habitat hunting
Aye-aye Daubentonia madagascariensis	2016 2018	Madagascar	unknown		habitat loss hunting

Species	Years listed	Location	Estimated population	IUCN status	Threats
Rondo dwarf galago Galagoides rondoensis	2006 2008 2010 2012	Tanzania	unknown		very small range habitat loss and fragmentation
Roloway monkey Cercopithecus roloway	2002 2006 2008 2010 2012	Côte d'Ivoire Ghana	unknown		hunting habitat loss and fragmentation
Tana River red colobus Piliocolobus rufomitratus	2002 2004 2006 2008 2012	Kenya	1,100–1,300		hunting habitat loss and fragmentation habitat degradation parasitic infection of isolated populations
Bioko red colobus Piliocolobus pennantii pennantii	2004 2006 2010 2012	Equatorial Guinea	fewer than 5,000		habitat degradation hunting small range
Eastern lowland gorilla Gorilla beringei graueri	2010 2012	Democratic Republic of the Congo	6,800		habitat loss and fragmentation hunting

Species	Years listed	Location	Estimated population	IUCN status	Threats
Javan slow loris Nycticebus javanicus	2008 2010 2012	Indonesia	unknown		live capture hunting habitat loss
Pig-tailed langur Simias concolor	2002 2004 2006 2008 2010 2012	Indonesia	700–3,347		habitat loss hunting live capture
Delacour's langur Trachypithecus delacouri	2000 2002 2004 2006 2008 2010 2012	Vietnam	fewer than 250		habitat fragmentation hunting
Golden-headed langur Trachypithecus poliocephalus	2000 2002 2004 2006 2008 2010 2012	Vietnam	60–70		habitat fragmentation hunting
Western purple-faced langur Semnopithecus vetulus nestor	2004 2006 2008 2010 2012	Sri Lanka	unknown		habitat loss and fragmentation dependent on gardens for survival live capture hunting other human factors
Grey-shanked douc Pygathrix cinerea	2000 2002 2004 2006 2008 2010 2012	Vietnam	600–700		restricted range habitat loss and fragmentation hunting live capture
Tonkin snub-nosed monkey Rhinopithecus avunculus	2000 2002 2004 2006 2008 2010 2012	Vietnam	200–250		habitat loss and fragmentation hunting
Eastern black crested gibbon Nomascus nasutus	2008 2010 2012	China Vietnam	around 110		habitat loss, fragmentation, and disturbance hunting
Pygmy tarsier Tarsius pumilus	2012	Indonesia	unknown		habitat loss

Species	Years listed	Location	Estimated population	IUCN status	Threats
Brown spider monkey Ateles hybridus	2004 2006 2008 2010 2012	Colombia Venezuela	unknown		habitat loss and fragmentation hunting live capture
Brown-headed spider monkey Ateles fusciceps fusciceps	2006 2012	Ecuador	unknown		habitat loss and fragmentation hunting
Kaapori capuchin Cebus kaapori	2012	Brazil	unknown		habitat loss and degradation hunting live capture
Rio Mayo titi Plecturocebus oenanthe	2012	Peru	unknown		habitat loss and fragmentation hunting live capture
Northern brown howler Alouatta guariba guariba	2012	Brazil	fewer than 250		habitat loss hunting disease epidemics

Former list members

With each new publication, species are both added and removed from the list. In some cases, removal from the list signifies improvement for the species. With the publication of the 2006–2008 list, four species were removed because of increased conservation efforts: the black lion tamarin, golden lion tamarin, mountain gorilla, and Perrier's sifaka. In 2008, the black lion tamarin went from critically endangered to endangered and the golden lion tamarin was similarly promoted in 2003 after three decades of collaborative conservation efforts by zoos and other institutions. Well-protected species such as these still have very small populations, and due to deforestation, new habitat is still needed for their long-term survival. The Hainan black crested gibbon, which was removed from the 2008–2010 list, still has fewer than 20 individuals left, but significant efforts to protect it are now being made. Mittermeier claimed in 2007 that all 25 species could be elevated off the list within five to ten years if conservation organizations had the necessary resources.
Unlike the changes in the 2006–2008 report, not all species were removed from the 2008–2010 list due to improvement in their situation. Instead, new species were added to bring attention to other closely related species with very small populations that are also at risk of extinction. For example, the highly endangered eastern black crested gibbon replaced the Hainan black crested gibbon. The Javan slow loris replaced the Horton Plains slender loris because the former has been hit the hardest of Asian lorises, all of which are declining rapidly due primarily to capture for the exotic pet trade, as well as use in traditional medicines and forest loss. In another case, the brown-headed spider monkey was omitted from the list since no spokesperson could be found for the species. The same approach was taken with the 2012–2014 list.

Species	Years listed	Location	Estimated population	IUCN status	Threats
Greater bamboo lemur Prolemur simus	2002 2004 2006 2008 2010	Madagascar	500 or fewer		small, isolated populations loss of habitat and fragmentation hunting reduced availability of drinking water due to climatic change extreme dietary specialization and dependency on giant bamboo
Black-and-white ruffed lemur Varecia variegata	2010	Madagascar	unknown		loss of habitat and fragmentation hunting
Gray-headed lemur Eulemur cinereiceps	2004 2006 2008	Madagascar	7,265 ± 2,268		very small range hybridization with red-fronted lemur low population densities habitat loss and fragmentation cyclones hunting
Golden-crowned sifaka Propithecus tattersalli	2000	Madagascar	6,000–10,000		hunting loss of habitat
Golden bamboo lemur Hapalemur aureus	2000	Madagascar	fewer than 5,916		loss of habitat hunting
Sahamalaza sportive lemur Lepilemur sahamalazensis	2006	Madagascar	unknown		loss of habitat hunting
Perrier's sifaka Propithecus perrieri	2000 2002 2004 2014 2016	Madagascar	around 915		loss of habitat hunting
Blue-eyed black lemur Eulemur flavifrons	2008 2010 2012	Madagascar	450–2,300		very small range loss of habitat hunting live capture
Northern sportive lemur Lepilemur septentrionalis	2008 2010 2012	Madagascar	around 19		very small range habitat loss hunting
Silky sifaka Propithecus candidus	2000 2002 2004 2006 2008 2010 2012	Madagascar	fewer than 250		very small range hunting habitat loss
Madame Berthe's mouse lemur Microcebus berthae	2012	Madagascar	fewer than 8,000		loss of habitat and fragmentation
Red ruffed lemur Varecia rubra	2012	Madagascar	unknown		loss of habitat hunting
Lavasoa Mountains dwarf lemur Cheirogaleus lavasoensis	2014	Madagascar	?
Gerp's mouse lemur Microcebus gerpi	2016	Madagascar	?
Ring-tailed lemur Lemur catta	2016	Madagascar	?

Species	Years listed	Location	Estimated population	IUCN status	Threats
Mount Rungwe galago Galagoides sp.	2004	Tanzania	unknown	Not evaluated	loss of habitat hunting
Sclater's guenon Cercopithecus sclateri	2000	Nigeria	unknown		habitat loss and fragmentation high human density hunting
Drill Mandrillus leucophaeus	2000	Cameroon Equatorial Guinea Nigeria	unknown		small range loss of habitat hunting
Tana River mangabey Cercocebus galeritus galeritus	2002	Kenya	1,000–1,200		loss of habitat hunting
Sanje mangabey Cercocebus sanjei	2000 2002 2004	Tanzania	fewer than 1,300		loss of habitat hunting
Sooty mangabey Cercocebus atys lunulatus	2000 2002 2004	Côte d'Ivoire Ghana	unknown		habitat loss and degradation hunting
Miss Waldron's red colobus Piliocolobus badius waldronae	2000 2002 2006	Côte d'Ivoire Ghana	unknown		very small populations habitat loss hunting
Mountain gorilla Gorilla beringei beringei	2000 2002 2004	Rwanda Uganda	around 880		two isolated populations political instability human diseases hunting
Niger Delta red colobus Procolobus epieni	2008 2010	Nigeria	unknown		very small range hunting habitat loss and degradation
Kipunji Rungwecebus kipunji	2006 2008	Tanzania	around 1,117		very small range habitat loss and fragmentation hunting
Cross River gorilla Gorilla gorilla diehli	2000 2002 2004 2006 2008	Cameroon Nigeria	200–300		small, restricted range habitat loss hunting

Species	Years listed	Location	Estimated population	IUCN status	Threats
Horton Plains slender loris Loris tardigradus nycticeboides	2004 2006	Sri Lanka	unknown		five isolated populations habitat loss hunting
Natuna Island surili Presbytis natunae	2002	Indonesia	fewer than 10,000		two isolated populations habitat loss and degradation live capture
White-headed langur Trachypithecus poliocephalus leucocephalus	2002	China, Vietnam	fewer than 250		very small populations habitat loss hunting
Miller's grizzled langur Presbytis hosei canicrus	2004	Indonesia	unknown		habitat loss and fragmentation hunting
Black snub-nosed monkey Rhinopithecus bieti	2002	China	fewer than 2,000		habitat loss pesticide use hunting
Gray snub-nosed monkey Rhinopithecus brelichi	2002	China	around 750		one isolated population habitat loss hunting
Silvery gibbon Hylobates moloch	2000	Indonesia	4,000–4,500		habitat loss and fragmentation live capture
Hainan black crested gibbon Nomascus hainanus	2000 2004 2006	China	around 20		extremely small population size suboptimal, protected habitat possible gender bias in recent births hunting
Siau Island tarsier Tarsius tumpara	2006 2008 2010	Indonesia	Low thousands at best	Not evaluated	island population very small range high human density hunting habitat degradation
Western hoolock gibbon Hoolock hoolock	2006 2008	Bangladesh India Myanmar	fewer than 5,000		very small populations habitat loss and fragmentation hunting live capture
Sumatran orangutan Pongo abelii	2000 2002 2004 2006 2008	Indonesia	around 6,600		recent, very rapid declines in numbers only 10 fragmented habitat units habitat loss and fragmentation hunting live capture
Northwest Bornean orangutan Pongo pygmaeus pygmaeus	2010	Indonesia Malaysia	unknown		habitat loss and fragmentation hunting live capture
Lion-tailed macaque Macaca silenus	2010	India	fewer than 4,000		habitat loss and fragmentation hunting

Species	Years listed	Location	Estimated population	IUCN status	Threats
Golden lion tamarin Leontopithecus rosalia	2000	Brazil	3,200		habitat loss and fragmentation live capture
Black lion tamarin Leontopithecus chrysopygus	2000	Brazil	around 1,000		small population size habitat loss and fragmentation
Superagui lion tamarin Leontopithecus caissara	2000 2002 2004	Brazil	fewer than 400		small, isolated populations habitat loss and degradation high human density hunting
Golden-bellied capuchin Cebus xanthosternos	2000 2002 2004	Brazil	unknown		habitat loss hunting
Northern muriqui Brachyteles hypoxanthus	2000 2002 2004	Brazil	fewer than 1,000		small, isolated populations habitat loss and fragmentation hunting
Yellow-tailed woolly monkey Oreonax flavicauda	2000 2006 2008 2010	Peru	unknown		restricted range low population densities habitat loss hunting live capture
Cotton-top tamarin Saguinus oedipus	2008	Colombia	fewer than 6,000		habitat loss and fragmentation live capture
Blond capuchin Cebus flavius	2010	Brazil	180		habitat loss and fragmentation live capture hunting

List history

With the exception of the 2000–2002 publication, which was written collaboratively by the IUCN/SSC PSG and CI, the list has been revised every two years following the biannual Congress of the IPS. The 2002–2004 list resulted from the 19th Congress of the IPS in Beijing, China; the 2004–2006 list followed the 20th Congress of the IPS, held in Torino, Italy; the 2006–2008 list after the 21st Congress in Entebbe, Uganda; the 2008–2010 list followed the 22nd Congress held in Edinburgh, UK; the 2010-2012 list followed the 23rd Congress in Kyoto, Japan; the 2012–2014 list after the 24th Congress in Cancún, Mexico; the 2014–2016 list after the 25th Congress in Hanoi, Vietnam; the 2016–2018 list after the 26th Congress in Chicago, US; the 2018–2020 list after the 27th Congress in Nairobi, Kenya; the 2022–2023 list after the 28th Congress in Quito, Ecuador; and the 2023–2025 list after the 29th Congress in Kuching, Malaysia.
The 2008 IUCN Red List of Threatened Species offered assessments of 634 primate taxa, of which 303 were listed as threatened. A total of 206 primate species were ranked as either critically endangered or endangered, 54 of which have been included at least once in The World's 25 Most Endangered Primates since 2000.

	Madagascar	Africa	Asia	Neotropics
2000–2002	Propithecus candidusPropithecus perrieriPropithecus tattersalliHapalemur aureusHapalemur griseus alaotrensis	Gorilla gorilla diehliGorilla b. beringeiCercocebus sanjeiCercocebus atys lunulatusProcolobus badius waldronaeCercopithecus sclateriMandrillus leucophaeus	Trachypithecus delacouriTrachypithecus p. poliocephalusPygathrix cinereaRhinopithecus avunculusPongo abeliiHylobates molochNomascus hainanus	Brachyteles hypoxanthusCebus xanthosternosLeontopithecus caissaraLeontopithecus rosaliaLeontopithecus chrysopygusOreonax flavicauda
2002–2004	Propithecus candidusPropithecus perrieriProlemur simus	Gorilla gorilla diehliGorilla b. beringeiCercocebus galeritus sanjeiCercocebus atys lunulatusProcolobus badius waldronaeProcolobus rufomitratusCercopithecus diana rolowayCercocebus g. galeritus	Trachypithecus delacouriTrachypithecus p. poliocephalusPygathrix cinereaRhinopithecus avunculusPongo abeliiSimias concolorPresbytis natunaeTrachypithecus poliocephalus leucocephalusRhinopithecus bietiRhinopithecus brelichiNomascus nasutus	Brachyteles hypoxanthusCebus xanthosternosLeontopithecus caissara
2004–2006	Propithecus candidusPropithecus perrieriProlemur simusEulemur cinereiceps	Gorilla gorilla diehliGorilla b. beringeiCercocebus galeritus sanjeiCercocebus atys lunulatusProcolobus rufomitratusProcolobus p. pennantiiGalagoides sp.	Trachypithecus delacouriTrachypithecus p. poliocephalusPygathrix cinereaRhinopithecus avunculusPongo abeliiSimias concolorLoris tardigradus nycticeboidesPresbytis hosei canicrusTrachypithecus vetulus nestorNomascus hainanus	Brachyteles hypoxanthusCebus xanthosternosLeontopithecus caissaraAteles hybridus brunneus
2006–2008	Propithecus candidusLepilemur sahamalazensisProlemur simusEulemur cinereiceps	Gorilla gorilla diehliProcolobus rufomitratusProcolobus p. pennantiiCercopithecus diana rolowayRungwecebus kipunjiGalagoides rondoensisProcolobus badius waldroni	Trachypithecus delacouriTrachypithecus p. poliocephalusPygathrix cinereaRhinopithecus avunculusPongo abeliiSimias concolorTrachypithecus vetulus nestorHoolock hoolockNomascus hainanusLoris tardigradus nycticeboidesTarsius tumpara	Ateles hybridusOreonax flavicaudaAteles f. fusciceps
2008–2010	Propithecus candidusLepilemur septentrionalisProlemur simusEulemur cinereicepsEulemur flavifrons	Gorilla gorilla diehliProcolobus rufomitratusCercopithecus diana rolowayRungwecebus kipunjiGalagoides rondoensisProcolobus epieni	Trachypithecus delacouriTrachypithecus p. poliocephalusPygathrix cinereaRhinopithecus avunculusPongo abeliiSimias concolorSemnopithecus vetulus nestorHoolock hoolockTarsius tumparaNycticebus javanicusNomascus nasutus	Ateles hybridusOreonax flavicaudaSaguinus oedipus
2010–2012	Eulemur flavifrons Lepilemur septentrionalisProlemur simusPropithecus candidusVarecia variegata	Cercopithecus diana rolowayGalagoides rondoensisPiliocolobus pennantii pennantiiPiliocolobus epieni Gorilla beringei graueri	Tarsius tumparaNycticebus javanicus Macaca silenusSimias concolorTrachypithecus delacouri Trachypithecus poliocephalusSemnopithecus vetulus nestorPygathrix cinereaRhinopithecus avunculusNomascus nasutusPongo pygmaeus pygmaeus	Ateles hybridusCebus flaviusCallicebus barbarabrownae Oreonax flavicauda
2012–2014	Propithecus candidusLepilemur septentrionalisEulemur flavifronsMicrocebus berthaeVarecia rubraIndri indri	Cercopithecus rolowayGalagoides rondoensisPiliocolobus pennantii pennantiiPiliocolobus rufomitratusGorilla beringei graueri	Trachypithecus delacouriTrachypithecus p. poliocephalusPygathrix cinereaRhinopithecus avunculusSimias concolorSemnopithecus vetulus nestorTarsius pumilusNycticebus javanicusNomascus nasutus	Ateles hybridusAteles fusciceps fuscicepsCebus kaaporiCallicebus oenantheAlouatta guariba guariba
2014–2016	Cheirogaleus lavasoensisHapalemur alaotrensisVarecia rubraLepilemur septentrionalisPropithecus perrieri	Galagoides rondoensisCercopithecus rolowayPiliocolobus preussiPiliocolobus rufomitratusGorilla beringei graueri	Carlito syrichtaNycticebus javanicusSimias concolorTrachypithecus delacouriTrachypithecus poliocephalusRhinopithecus avunculusSemnopithecus ajaxSemnopithecus vetulus nestorNomascus hainanusPongo abelii	Ateles hybridusAteles fusciceps fuscicepsCebus kaaporiCallicebus oenantheAlouatta guariba guariba
2016–2018	Microcebus gerpiHapalemur alaotrensisLemur cattaLepilemur jamesorumPropithecus perrieriDaubentonia madagascariensis	Paragalago orinusCercopithecus rolowayColobus vellerosusPiliocolobus epieniGorilla beringei graueri	Nycticebus javanicusSimias concolorTrachypithecus poliocephalusRhinopithecus avunculusTrachypithecus geeiSemnopithecus vetulusMacaca nigraNomascus hainanusPongo pygmaeus	Plecturocebus caquetensisCebus kaaporiAlouatta guariba guaribaAteles geoffroyiAteles fusciceps
2018–2020	Microcebus manitatraHapalemur alaotrensisLepilemur jamesorumIndri indriDaubentonia madagascariensis	Paragalago rondoensisCercopithecus rolowayRungwecebus kipunjiColobus vellerosusPiliocolobus epieniPiliocolobus rufomitratusPan troglodytes verus	Nycticebus javanicusSimias concolorTrachypithecus poliocephalusTrachypithecus geeiSemnopithecus vetulusHoolock tianxingPongo tapanuliensis	Callithrix auritaSaguinus bicolorCebus aequatorialisPlecturocebus olallaeAlouatta guaribaAteles geoffroyi
2022–2023	Microcebus berthaeLepilemur septentrionalisEulemur flavifronsPropithecus coquereli	Paragalago rondoensisCercocebus chrysogasterErythrocebus baumstarkiCercopithecus rolowayPiliocolobus epieniPan troglodytes ellioti	Nycticebus javanicusTarsius sangirensisSemnopithecus vetulusTrachypithecus poliocephalusPresbytis femoralisRhinopithecus brelichiHoolock tianxingPongo tapanuliensis	Callithrix flavicepsCebus kaaporiCebus aequatorialisPlecturocebus grovesiAlouatta guaribaAteles fusciceps fuscicepsAteles geoffroyi
2023–2025	Microcebus berthaeLepilemur septentrionalisMirza coquereliVarecia rubra	Paragalago rondoensisCercocebus chrysogasterErythrocebus baumstarkiCercopithecus erythrogasterPiliocolobus epieniGorilla gorilla diehli	Xanthonycticebus intermediusTarsius sangirensisTrachypithecus poliocephalusSimias concolorRhinopithecus strykeriPresbytis femoralisPresbytis chrysomelasNomascus nasutusPongo tapanuliensis	Plecturocebus olallaeCallicebus barbarabrownaeSaguinus bicolorSaimiri oerstediiLagothrix flavicaudaAteles hybridus