Granted the dubious honour of being one of the International Primatological Society’s ‘World’s Top 25 Most Endangered Primates’, the white-headed langur is in the company of such conservation priorities as the Sumatran orangutan (Pongo abelii) and the eastern gorilla (Gorilla beringei) (6). The focus of conservation efforts must fall primarily on the Cat Ba Island subspecies, with possibly as few as 59 individuals remaining today. This shockingly low number is the result of a massive 98% decline over the course of 40 years, from between 2,500 and 2,800 individuals in the 1960s to just 53 in 2000. Such a dangerously small population of Cat Ba langurs gives the impression that the Chinese subspecies, Trachypithecus poliocephalus leucocephalus, is thriving, with between 600 and 800 individuals alive today. This is, of course, far from the truth, particularly as declines were recorded in the populations at Longgang National Nature Reserve and the Fusui Rare and Precious Animal Reserve in 1998 (5).
In both range states of this monkey species, the major threat is hunting, which is exacerbated by habitat destruction and exploitation; for the creation of sugarcane plantations in China (5), and for timber, fuel-wood, honey, bamboo shoots, edible roots, and frogs and geckos in Vietnam (7). Cat Ba Island has seen considerable change in the past 20 – 30 years. Prior to 1979 very few people lived on the island, but it is now home to a large population, of whom 12,300 live in the buffer zone of Cat Ba National Park, and 850 in the park itself. Until 1989 commercial logging took place but this is no longer viable due to the scarcity of large trees (7).
Hunting of this rare primate is not for food, as the meat is said to be smelly and fetid, but for the creation of ‘monkey balm’, a traditional ‘medicinal’ preparation. Currently the Cat Ba langurs are split into just a few isolated sub-populations, many of which are all-female groups. This fragmentation creates further challenges for the recovery of the population due to low reproductive rates and the dangers of inbreeding (3).