The Cross River Gorilla (Gorilla gorilla diehli), found in Cameroon and Nigeria, and the Tapanuli Orangutan (Pongo tapanuliensis), found on the Indonesian island of Sumatra, are among the 25 most endangered primates in the world, according to a new report.
Primates in Peril: The World’s 25 Most Endangered Primates 2023–2025 has been brought out by an international team of primate researchers and lists 25 most endangered primates across Asia, Africa, Madagascar and South America for the years 2023-2025.
The 2023-2025 list of the world’s 25 most endangered primates has six species from Africa, four from Madagascar, nine from Asia, and six from the Neotropics (South America).
Indonesia and Madagascar both have four, China, Nigeria and Vietnam have three, Brazil, Malaysia, and Tanzania have two, and Benin, Bolivia, Brunei, Cameroon, Colombia, Costa Rica, Democratic Republic of the Congo, Laos PDR, Myanmar, Panama, Peru, Singapore, Togo and Venezuela each have one.
According to the report, 15 of the primates were not on the previous (2022-2023) list. Eight of them are listed as among the world’s most endangered primates for the first time.
“Nine primates — the Red Ruffed Lemur, Cross River Gorilla, Pig-tailed Snub-nosed Langur, Cao-vit Gibbon, Olalla Brothers’ Titi, Peruvian Yellow-tailed Woolly Monkey, Variegated Spider Monkey, Caatinga Titi Monkey and Pied Tamarin — were listed on previous iterations but were subsequently removed to call attention to other highly threatened species,” according to the report.
Two primates found in Northeast India and Bangladesh —Phayre’s Langur and the Western Hoolock Gibbon — were among species considered for the final list, although they did not make it.
The Phayre’s Langur (Trachypithecus phayrei), according to the report, is one of the least-studied Asian colobines or leaf-eating monkeys. Its distribution was recently restricted to eastern Bangladesh, northeastern India, and western Myanmar.
The species has been listed as ‘Endangered’ for two decades on the International Union for Conservation of Nature Red List of Threatened Species.
“No recent population estimates are available but populations are suspected to have declined by 50% to 80% over the last three generations. Several isolated small populations have already extirpated in India and Bangladesh due to hunting and habitat loss. Furthermore, many of the remaining habitats are small, fragmented, and isolated,” the report noted.
Mixed-species groups and putative hybrids between Phayre’s and capped langurs (T. pileatus) have been recently detected and may represent another threat.
Other threats include the direct loss of individuals because of illegal trading of live animals, electrocution, and roadkill.
“An assessment of current population size, genetic structure, and viability of small populations is needed to develop a proper conservation action plan. Mitigation of hunting, trading, habitat loss, and fragmentation is urgent by implementing laws, engaging local communities, environmental education, and building capacity at national scales. Habitat connectivity should be increased through restoration, corridors, and transboundary conservation measures. Translocation of small, isolated populations and rewilding of confiscated individuals is recommended,” the document stated.
The other primate from India and Bangladesh, the Western Hoolock Gibbon (Hoolock hoolock), is one of 20 species of gibbons and is listed as Endangered on the IUCN Red List of Threatened Species.
It is found in Eastern Bangladesh, northeastern India, and in the west of the Ayeyarwaddy and Chindwin rivers in Myanmar.
“Continuous loss of habitat resulting from encroachment, uncontrolled harvesting of natural resources, infrastructure development, the establishment of tea gardens, jhum or shifting cultivation, habitat fragmentation, and hunting for food and medicine, and capture for the illegal wildlife trade are the primary threats. Localized extinctions were observed in isolated fragments in northeast India and Bangladesh. The population trend is declining in India and Bangladesh. While the Myanmar population could be considered stable owing to having the largest continuous suitable habitat remaining, the threats are still found in some areas,” the report noted.
The authors recommended all possible efforts must be made to prevent further loss of habitat.
They also suggested measures like restoration of degraded habitats, creation of ecological corridors, further research, training of forest rangers, education and awareness programs among relevant stakeholders and community-based conservation initiatives in its range and making the western hoolock gibbon as flagship species.
“Above all, successful conservation of the species demands intensive intervention from the government,” the report stated.