Meet the Planet's 25 Most Endangered Primates

Earth is a primate planet, thanks mainly to the estimated 7.5 billion humans who inhabit and reshape its surface. But behind this conspicuous sea of people, the story of Earth's roughly 700 other primate species and subspecies is a lot less triumphant.

More than half of those primates are now in grave danger of becoming extinct, warns a report by the world's top primatologists and conservationists. Our closest living relatives are being wiped out by large-scale habitat destruction — especially from the burning and clearing of tropical forests, hunting for food, and the illegal wildlife trade.

That's according to the latest list of Earth's 25 most endangered primates, which is updated every two years by scientists from the International Union for the Conservation of Nature (IUCN), the Bristol Zoological Society (BZS), the International Primatological Society (IPS), and Conservation International (CI).

Here's the list of the 25 most endangered primates on the planet, according to the IUCN Primates in Peril report.

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Lake Alaotra Gentle Lemur

Adult Alaotran gentle lemur (Hapalemur alaotrensis) in papyrus vegetation in Alaotra marsh, near Andreba Gare village (Madagascar) — The Lac Alaotra bamboo lemur lives only in papyrus reeds around Lac Alaotra, Madagascar.
Jotaguru / Wikimedia Commons / CC BY 3.0

The critically endangered Lake Alaotra Gentle Lemur, or Lac Alaotra Bamboo Lemur (Hapalemur alaotrensis), is called the bandro by locals. IUCN estimates the current population to be at 2,500 individuals. This lemur is the only primate to live only in wetlands, as it resides in Madagascar's shrinking Lake Alaotra marsh. Conservation work has ended the hunting of the lemur for food, but Lake Alaotra marshlands' agricultural use still hurts the population.

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Bemanasy Mouse Lemur

The Bemanasy mouse lemur (Microcebus manitatra), which was identified as a separate species in 2016, lives in a southeastern Madagascar forest fragment. It is under threat from logging and slash-and-burn agriculture. Very few individuals are thought to live in these forest fragments. At just over 10 and a half inches, they are one of the larger mouse lemurs. Their coat is greyish brown on their back and tail. The underside of the coat is beige with some dark fur undercoat.

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James’ Sportive Lemur

The James' Sportive Lemur (Lepilemur jamesorum) dwells in the Manombo Special Reserve region in southeastern Madagascar. There are currently two populations in forest reserves. Deforestation and hunting led to their critically endangered status and an estimated population of around 1,386 total individuals. Hunters use traps and cut down the trees the lemur inhabits and remove them from their holes.

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Indri

The indri (Indri indri), also called the babakoto, is found in Madagascar's eastern rainforests and is the only lemur that sings. In addition to their singing abilities, they have a teddy bear appearance with short, dense fur, round ears, and small eyes. Long protected by taboos against hunting the species, the indri now faces extinction resulting from hunting and deforestation. According to the IUCN report, the estimated population size lies somewhere between 1,000 and 10,000 individuals.

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Aye-Aye

The aye-aye (Daubentonia madagascariensis) has the broadest range of any lemur, as their ability to consume a varied diet allows aye-ayes geographic flexibility. The aye-aye uses its long middle finger to tap on trees to find grubs, which is called percussive foraging. Aye-ayes are the only primate to use this form of echolocation to find food.

Poaching is the primary population threat to the endangered aye-ayes. Reliable population estimates are unavailable due to their solitary nature and enormous individual territories.

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Rondo Dwarf Galago

small brown lemur with glowing eyes hides on vine — Courtesy of Andrew Perkin

The Rondo dwarf galago or Rondo bushbaby (Paragalago rondoensis) found in Tanzania is notable for being the smallest known galago and sports a bottlebrush tail. They have a distinctive "double-unit rolling call." Forest habitat loss is the primary threat to the Rondo bushbaby, which has led to its critically endangered status. The most recent population count of the species was four individuals in 2008.

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Roloway Monkey

The endangered Roloway monkey (Cercopithecus roloway), called boapea by locals, is found in the tropical forests of the Côte d’Ivoire and Ghana and sports a long, distinctive beard. Fewer than 2,000 individuals remain, and some parts of their former range have no remaining roloway monkeys. According to the report, the bushmeat trade decimates their numbers each year, as 80 percent of Ghana's rural people rely on bushmeat as their primary source of protein.

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Kipunji

The kipunji (Rungwecebus kipunji), first discovered in 2003, lives solely in the mountain habitats around Mount Rungwe in Tanzania. They have a particularly notable and very loud, low-pitched honk-bark. Kipunji serves as the flagship species for conservation work in the area. There have been significant strides in restoring the habitat, although they are still in grave danger of extinction — 1,117 individuals in 38 groups remain.

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White-Thighed Colobus

The white-thighed colobus (Colobus vellerosus) has a fragmented distribution in eastern Africa from the area between the Sassandra and Bandama Rivers in Ivory Coast to Benin and possibly extending into southwestern Nigeria. Adults are primarily black with white with markings on their thighs and face and have an entirely white tail. An infant colobus is born with all-white fur, which darkens beginning around three months of age.

Critically endangered, this animal's numbers are rapidly declining due to uncontrolled hunting. The current population is estimated to be below 1,200.

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Niger Delta Red Colobus

The Niger Delta red colobus (Piliocolobus epieni) inhabits the forested marsh between the Forcados-Nikrogha Creek and the Sagbama-Osiama-Agboi Creek in Nigeria. Until 2008, this was considered a subspecies. The area's instability has worsened habitat destruction while hunting pressures on the population have caused this species to drop to an estimated few hundred individuals. The Niger Delta red colobus is considered critically endangered and faces a real threat of extinction.

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Tana River Red Colobus

The Tana River in northern Kenya is home to this red colobus (Piliocolobus rufomitratus). Its body is about 2 feet long, with a tail of over 31 inches. The coat of this endangered monkey is red or dark red. Hydroelectric dam construction and the rapidly increasing human population in the area are responsible for reducing this species' numbers. The dam construction is changing the vegetation in the area, which reduces the availability of appropriate food. IUCN lists it as critically endangered, with fewer than 1,000 individuals remaining.

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Western Chimpanzee

Found in the rainforest and savannah woodland of Côte d’Ivoire, Ghana, Guinea-Bissau, Liberia, Mali, Republic of Guinea, Senegal, and Sierra Leone, the western chimpanzee (Pan troglodytes verus) population declined by an estimated 80 percent between 1990 and 2014. At this rate, IUCN estimates by 2060, 99 percent of the remaining western chimpanzees will be gone. The leading threat to western chimpanzees is illegal hunting. The current population is estimated to be between 35,000 and 55,000 individuals, although it is classified as critically endangered.

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Pig-Tailed Snub-Nose Langur

Commercial logging has created the primary threat to the critically endangered pig-tailed snub-nose langur (Simias concolor) in Indonesia's Mentawai Islands. They have a long dark coat and smooth face with a small ski slope nose. The soil and tree damage makes the habitat incapable of supporting this species and other primates that call the forests home. Additionally, it makes for easier hunting of the pig-tailed snub-nosed langur, whose meat is considered a delicacy. Hunters use rifles from their vehicles on the new logging roads to kill the monkey. As a result, only an estimated 3,347 individuals remain.

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Javan Slow Loris

The Javan Slow Loris (Nycticebus javanicus) of Indonesia should have natural protection from their species' biggest threat: capture for the illegal pet trade. They are the only venomous mammal, but their venom fails to stop wildlife traders, who pull out their teeth and post videos of them on social media. The Javan Slow Loris is listed as critically endangered with uncertain population numbers. Conservation efforts, however, are aimed at trending these numbers upward.

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Cat Ba Langur

The Cat Ba Langur is also known as the golden-headed langur (Trachypithecus poliocephalus) and can only be found on Vietnam's Cat Ba Island. Their bodies are dark brown or black in color. From the shoulders up, they are covered in golden brown fur with some white. Infant Cat Ba langurs are bright orange. Poaching for traditional medicinal purposes is the main threat to Cat Ba langurs, which resulted in the once abundant population plummeting to around 50 in 2000. Conservation efforts have led to a slow increase in the numbers, but this animal remains critically endangered.

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Golden Langur

The Golden Langur or Gee's golden langurs (Trachypithecus geei), native to India and Bhutan, was first discovered by E.P. Gee in 1953. The golden in the animal's name is for the golden-orange fur that is only present during the breeding season. For the rest of the year, they are cream or dirty white. Major threats are power lines, road accidents, and dog attacks. With less than 12,000 individuals remaining in the wild, IUCN lists them as endangered.

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Purple-Faced Langur

The purple-faced langurs (Semnopithecus vetulus) of Sri Lanka face an uncertain future. Deforestation in Sri Lanka's dense Colombo region is the main reason why the western purple-faced langur is critically endangered. The animal now lives in close quarters with humans because of urbanization, which led to their diet changing from one of mostly leaves to one made up of fruit. Ecotourism and programs for children seem to be the most effective protection for the species.

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Gaoligong Hoolock Gibbon

endangered Skywalker hoolock gibbon in trees — Courtesy of Lee Harding

The Gaoligong hoolock gibbon, or Skywalker hoolock gibbon (Hoolock tianxing), has fewer than 150 individuals remaining and is a critically endangered species. This hoolock gibbon has the same white eyebrows as other hoolocks but has brown and black tufts of hair between males' legs. This gibbon had lost more than 90 percent of its habitat on the Salween River's west bank in China by 1994. Regrettably, habitat loss isn't the only threat; hunting for bushmeat and the pet trade further endanger the species.

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Tapanuli Orangutan

Once thought to be the southernmost population of Sumatran orangutans, the critically endangered Tapanuli orangutan (Pongo tapanuliensis) was formally identified as a separate species in 2017. Only around 760 individuals remain due to habitat loss from illegal logging and poaching for the pet trade. A proposed hydroelectric dam threatens the remaining population, as these tree-dwelling apes never go to ground level. Roads that cause a break in the trees mean they cannot move from one area of the forest to another.

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Buffy-Tufted-Ear Marmoset

Buffy-tufted marmoset (Callithrix aurita) in Nazaré Paulista, Brazil — Jack Hynes / Wikimedia Commons / CC BY-SA 3.0

The buffy-tufted-ear marmoset (Callithrix aurita), which resides in coastal Brazil, primarily eats insects. Their facial structure doesn't allow them to strip bark from trees to access tree sap and gums, a characteristic that makes them unusual for marmosets.

Invasive marmoset species, habitat loss and fragmentation, and an outbreak of yellow fever have decimated the population, leaving fewer than 1,000 individuals of the critically endangered species.

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Pied Tamarin

Pied bare-faced tamarin — belizar73 / Getty Images

The pied tamarin (Saguinus bicolor) is also known as the Brazilian bare-faced tamarin and has a native range around Manaus, the capital of Brazil's Amazonas state. City life doesn't agree with them, where cats, dogs, power lines, and cars, along with humans capturing them for the pet trade, threaten their numbers. They are critically endangered and are thought to be declining, though no reliable population estimates are available.

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Ecuadorian White-Fronted Capuchin

White fronted Capuchin mother grooms her baby for insects on branch off Napo river. — Rebecca Yale / Getty Images

Only 1 percent of the original range of the Ecuadorian white-fronted capuchin (Cebus aequatorialis) remains in the Chocó and Tumbes eco-regions of Ecuador and Peru. These tree-dwelling monkeys are considered pests by locals, particularly those living on corn, banana, cacao, and plantain plantations. They provide crab hunting competition in mangrove regions. This animal is listed as critically endangered with an unknown number of mature individuals.

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Olalla Brothers’ Titi Monkey

There was no further information about the species for 60 years after the first description of a single Olalla Brothers' Titi monkey (Plecturocebus olallae). Finally, in 2002, Wildlife Conservation Society researchers located the monkeys again. The small population lives in the Moxos Savannah in Bolivia and is threatened by ranchers burning the area for cattle pastures. Fewer than 2,000 individuals remain, according to Primates in Peril, and they are critically endangered.

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Brown Howler Monkey

Northern brown howler monkeys (Alouatta guariba ) serve as important seed dispersers with their diet of fruit and leaves in Brazil's Atlantic forest. Critically endangered, their habitat has shrunk dramatically due to coffee and sugar cultivation and cattle ranching. Additionally, yellow fever outbreaks have severely depleted their numbers. Scientists believe that fewer than 250 mature animals are still alive. The southern brown howler monkeys also have declining populations, according to the report.

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Central American Spider Monkey

The Central American spider monkey, also known as Geoffroy's spider monkey (Ateles geoffroyi), has various subspecies in Mexico, Guatemala, Nicaragua, Honduras, El Salvador, Costa Rica, and Panama. They have a limited diet of mostly fruits and spend much of their time foraging. Endangered with further decreasing numbers, fewer than 1,000 individuals remain.