Cat Ba Langur – White-headed Langur – Trachypithecus poliocephalus

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Taxonomy and Classification Cat Ba Langur:

Regnum: Animalia
Phylum: Chordata
Class: Mammalia
Ordo: Primates
Familiar: Cercopithecidae
Genus: Trachypithecus
Species: Trachypithecus poliocephalus ssp.

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Belonging to the Trachypithecus genus, the Cat Ba Langur is characterized by its distinctive grayish-black fur, complemented by striking white sideburns and a crown of silver-gray hair atop its head. Their long limbs and prehensile tails enable agile movements through the limestone karst formations, where they call home.

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Habitat and Distribution:

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Cat Ba Langur on their habitat – Photo by Neahga Leonard

The Cat Ba Langur finds solace in the limestone forests of Cat Ba Island, part of the Ha Long Bay archipelago. This unique habitat, characterized by towering limestone cliffs and dense vegetation, creates an ecological niche for the langurs. Unfortunately, their distribution is highly restricted, making them vulnerable to habitat loss and fragmentation.

Behavior and Social Structure:

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Cat Ba Langur - White-headed Langur - Trachypithecus poliocephalus 16

These langurs exhibit a complex social structure, living in cohesive groups led by a dominant male. They are known for their acrobatic feats as they traverse the karst landscapes, leaping between limestone outcrops. Vocalizations and grooming play a crucial role in communication, fostering social bonds within the group.

Reproductive Biology:

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Young Cat Ba Langur – Photo by Dinh Muoi

The Cat Ba Langur’s reproductive biology is integral to its survival. Females give birth to a single offspring after a gestation period of approximately six months. Breeding happens through the year with winter months showing a large increase in frequency of births.  February and April are the months with the most births.  Given the approximately 6-month gestation period this indicates that the peak conception month is August, near the end of the rainy season. The close-knit social structure ensures cooperative care for the young, enhancing their chances of survival in the challenging karst environment.

Conservation Status:

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Conservation status – © IUCN redlist

Classified as Critically Endangered by the International Union for Conservation of Nature (IUCN), the Cat Ba Langur faces severe threats. With an estimated population of around 60 individuals, habitat loss, and poaching pose immediate dangers.

Poaching, primarily for traditional “medicine” with secondary hunting for sport, has been recognized as the most severe historical threat to Cat Ba Langurs, and the reason for the precipitous decline in their population over the past decades. Reproductively valuable males were often the most common victims due to their behavior. This is highly questionable, however, as their behavior is not enormously different and, if anything, females would be easier to hunt as they are often grouped together and there are more of them per group.

Habitat disturbance and fragmentation resulting from the growing human population on Cat Ba Island (due in large part to the country’s designation of the island as a new tourism center for northern Viet Nam), and rampant fires due to honey collectors are also threats.

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In the heart of Cat Ba Island, the Cat Ba Langur epitomizes the fragile beauty of Vietnam’s natural heritage. As we navigate the nuances of its taxonomy, behavior, and conservation status, a rallying cry emerges for collective action. Preserving the limestone karst habitats and ensuring the protection of the Cat Ba Langur are essential steps towards safeguarding this remarkable primate for future generations and sustaining the ecological balance of Vietnam’s unique landscapes.

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