Delacour’s langur (Trachypithecus delacouri) reintroduction program: A preliminary report on the trial release into the Trang An UNESCO World Heritage Site, Ninh Binh Province, Vietnam

At the present time, the Van Long Nature Reserve Ninh Binh Province is home to the only viable sub-population of the ‘Critically Endangered’ Delacour’s langur (Trachypithecus delacouri). The reserve contains about 200 individuals. The next largest sub-population of about 80 individuals exists in neighboring Ha Nam Province, in a currently unprotected area. Such small and isolated populations have heightened vulnerability to internal and external threats to their survival. The establishment of further sub-populations in suitable, secure and sustainable locations, therefore, is a crucial step towards helping to safeguard the survival of this species. Until the late 1990’s a small population is known to have existed in the Trang An limestone massif, Ninh Binh Province. In 2014 Trang An was inscribed as UNESCO World Heritage Site. With strict protection of the area now in place and the existing and excellent habitat that the massif offers for Delacour’s langurs, the establishment of a new sub-population here was recommended soon after its inscription and is included in the “Urgent Action Plan for the Conservation of Primates in Vietnam until 2020, Vision 2030”. The Endangered Primate Rescue Center (EPRC), located in Cuc Phuong National Park, started breeding programs for several species of highly endangered primates in 1993, with the goal of releasing captive born individuals to support depleted wild populations or to establish new populations where the species has been extirpated. In 2017 a collaborative venture between local, national and international stakeholders was initiated to set in motion a reintroduction program for Delacour’s langurs in Trang An. In August 2020, a group of three captive-born Delacour’s langurs was transferred to an island in the World Heritage Site as a first step towards a possible re-establishment of a sub-population in this area.