Eastern Black Crested Gibbon – “Cao-vit Gibbon” – Nomascus nasutus

Nestled within the dense, emerald-green forests of Vietnam, the Eastern Black Crested Gibbon (Nomascus nasutus), also known as the Cao-vit black crested gibbon or the Cao-vit crested gibbon, emerges as a symbol of the country’s unique and fragile biodiversity. The term “Cao-vit” originated from the sounds of their calls or songs that villagers of Ngoc Khe, Phong Nam and Ngoc Con communes of Trung Khanh District, Cao Bang Province of Vietnam use to name them. This name was officially used by gibbon experts since the rediscovery.

Taxonomy and Classification – Eastern Black Crested Gibbon:

Regnum: Animalia
Phylum: Chordata
Class: Mammalia
Ordo: Primates
Familiar: Hylobatidae
Genus: Nomascus
Species: Nomascus nasutus

Belonging to the Nomascus genus, the Eastern Black Crested Gibbon is distinguished by its sleek black fur, a striking crest of hair crowning its head, and long, slender limbs. Males and females exhibit subtle differences in coloration, with the males often boasting a more prominent crest. Their agile and acrobatic movements through the forest canopy reflect not only their physical prowess but also their adaptation to the intricate ecosystems they inhabit.

Habitat and Distribution:

Thriving amidst the towering trees of Vietnam’s evergreen forests, these gibbons find sanctuary in the Annamite Range. This mountainous terrain, stretching through both Vietnam and Laos, provides the ideal habitat with dense canopies, offering protection and sustenance. Unfortunately, the Eastern Black Crested Gibbon’s distribution is increasingly confined to fragmented patches of primary and secondary forests, raising concerns about its long-term survival.

Behavior and Social Structure:

Beyond their distinctive appearance, the Eastern Black Crested Gibbons are known for their captivating melodious calls that echo through the treetops. Living in small family groups, they form strong monogamous bonds. Their social structure is characterized by cooperation and intricate communication through vocalizations, ensuring the cohesion of the family unit. Acrobatic displays in the treetops showcase not only their agility but also the sophistication of their social interactions.

Reproductive Biology:

Reproductive strategies are vital for the survival of any species, and the Eastern Black Crested Gibbon is no exception. Monogamous pairs engage in elaborate courtship rituals, strengthening their bonds through grooming and mutual displays. The gestation period for females is around seven months, and the birth of a single offspring is a significant event within the social group. Infant gibbons are nurtured and protected by both parents, emphasizing the cooperative nature of their familial bonds.

Conservation Status:

Despite their resilience, Eastern Black Crested Gibbons face a critical threat to their existence. Classified as Critically Endangered by the International Union for Conservation of Nature (IUCN), their population has drastically declined due to habitat loss, hunting, and the illegal pet trade.

What little remains of the species’ habitat is under pressure from fuel wood collection, cultivation in valley bottoms, and livestock grazing, especially of goats, by local Vietnamese and Chinese ethnic minorities. Hunting of this transboundary gibbon population has been controlled with the gazettement of protected areas in both Vietnam and China and subsequent enforcement, although hunting of other taxa does still occur.

It should be noted that even occasional hunting events of gibbons would be very detrimental to the species’ long-term viability, and continued vigilance is required. Problems intrinsic to small, single populations may pose a significant long-term risk to population viability through inbreeding, disease outbreaks, extreme weather events and fires and climate change. A recent Population and Habitat Viability Analysis exercise suggested that the last remaining population of these gibbons may be reaching carrying capacity, making habitat restoration a significant priority.

Why don’t you visit Vietnam on a primate discovery tour? Click here.

Conclusion:

In the heart of Vietnam’s Annamite Mountains, the Eastern Black Crested Gibbon’s tale unfolds—a story of resilience, intricate social structures, and the challenges of coexisting with an ever-changing environment. As we navigate the complexities of their taxonomy, behavior, and conservation status, let us heed the call to protect and preserve, ensuring that the haunting calls of the Eastern Black Crested Gibbon continue to resonate through the canopies of Vietnam’s precious forests for generations to come.