**Cat Ba langur (Trachypithecus poliocephalus)**

One of the world’s rarest primates, restricted to a single island in northern Vietnam.

Context

A small breeding group maintained in one of the large enclosures at the Endangered Primate Rescue Center (EPRC), located within Cuc Phuong National Park, Vietnam. The individual pictured here is an adult male.

Field notes

The Endangered Primate Rescue Center is one of the few institutions in the world maintaining Cat Ba langurs under human care and has played a particularly important role in their conservation breeding. It also houses numerous other threatened Vietnamese primates and is among the most important facilities dedicated to the conservation of the country’s endemic primate fauna.

The small family group maintained at EPRC has reproduced on several occasions, providing hope that conservation breeding could eventually help reinforce the wild population if such intervention becomes necessary and feasible.

Equally importantly, the centre has enabled researchers and conservationists to collect valuable scientific data on many poorly known and critically endangered Vietnamese primates. Several pioneering breeding successes have been achieved there, while the institution also contributes to conservation initiatives, scientific research, and education programmes throughout Vietnam.

Key facts

The species is endemic to Cat Ba Island, in the Ha Long Bay region of northern Vietnam, and belongs to a group of Southeast Asian langurs specialized for life in limestone karst habitats.

Unlike most other langurs of the genus Trachypithecus, the Cat Ba langur retains conspicuous orange or golden coloration on its head and sometimes its shoulders. Infants are born with a predominantly bright orange coat before gradually developing the darker coloration of adults as they mature.

Monitoring wild populations is particularly challenging because most remaining groups inhabit steep, inaccessible limestone cliffs and forested karst formations. Many of these areas can only be surveyed effectively from the sea or from a limited number of observation points.

Conservation

The species is currently listed as Critically Endangered on the IUCN Red List and is considered one of the rarest primates on Earth.

Historical estimates suggested that approximately fifty individuals survived in the wild, all restricted to the remaining limestone forest habitats of Cat Ba Island. The population suffered severe declines as a result of hunting and habitat disturbance, with some estimates indicating a reduction from around seventy to fifty individuals during the 2010s. Current population figures require continued monitoring and regular reassessment.

Protection measures on Cat Ba Island have improved through dedicated conservation efforts, including habitat protection, anti-poaching activities, and population monitoring. The work carried out by EPRC remains particularly valuable through conservation breeding, scientific research, and education programmes that support the long-term survival of this exceptional primate.