Hollongapar Gibbon Sanctuary

Situated in the Jorhat district of Assam, Hollongapar Gibbon Sanctuary is one of India’s most unique protected areas, renowned for being the country’s only sanctuary dedicated to the protection of the hoolock gibbon, the only ape species found in India. Spanning approximately 21 square kilometres, this evergreen forest serves as an important refuge for diverse flora and fauna and is an example of Assam’s rich biodiversity.

Geographical Setting and Location

The sanctuary lies about 20 kilometres from Jorhat town, surrounded by tea gardens and human settlements. It was originally a part of the larger forest range that extended to Nagaland but became isolated due to extensive deforestation and encroachment. The sanctuary is bordered by tea estates such as Dissoi, Katoni, and Hoollong Tea Estates, and the Dissoi River forms its southern boundary. The elevation varies from 100 to 120 metres above sea level, and the area experiences a humid subtropical climate with heavy monsoon rainfall between May and September.
The sanctuary is named after the Hollong tree (Dipterocarpus macrocarpus), which is the state tree of Assam and dominates the upper canopy. The lush evergreen vegetation and dense canopy make it a significant ecological zone for the conservation of arboreal species.

History and Establishment

The sanctuary was first declared a ‘Reserve Forest’ in 1881 during the British colonial period and was then known as the Hollongapar Reserve Forest. Owing to its rich biodiversity, it was upgraded to a Wildlife Sanctuary in 1997 and renamed the Hollongapar Gibbon Sanctuary. The primary aim of this designation was to ensure the protection of the western hoolock gibbon (Hoolock hoolock) and other associated species.

Flora and Vegetation

The vegetation of the sanctuary is classified as semi-evergreen to evergreen forest, dominated by tall Hollong trees reaching heights of 30–40 metres. Other important tree species include Amari (Amoora wallichii), Sam, Bhelu, Titachapa, and Ajhar. The understorey vegetation comprises shrubs, herbs, ferns, and thick bamboo groves, especially Dendrocalamus hamiltonii and Bambusa pallida.
The forest supports a multilayered canopy structure that provides a suitable habitat for arboreal primates. Seasonal flowering and fruiting cycles sustain various species throughout the year, making the sanctuary an ecologically balanced environment.

Faunal Diversity

The sanctuary’s most notable inhabitants are its primates. It harbours all seven species of primates found in Assam, namely:

• Western hoolock gibbon (Hoolock hoolock)
• Stump-tailed macaque (Macaca arctoides)
• Northern pig-tailed macaque (Macaca leonina)
• Assamese macaque (Macaca assamensis)
• Rhesus macaque (Macaca mulatta)
• Capped langur (Trachypithecus pileatus)
• Slow loris (Nycticebus bengalensis)

The western hoolock gibbon is an arboreal and diurnal primate, known for its distinctive whooping calls and monogamous social structure. The sanctuary provides one of the last remaining strongholds for this endangered species in India.
In addition to primates, the forest supports a wide range of mammals such as Indian elephants, leopards, jungle cats, civets, and squirrels. Avifaunal diversity is equally remarkable, with more than 200 species of birds including hornbills, woodpeckers, drongos, and barbets. Reptiles and amphibians like pythons, monitor lizards, and various frog species also thrive in the moist forest conditions.

Conservation Importance

Hollongapar Gibbon Sanctuary plays a crucial role in the conservation of fragmented lowland rainforest ecosystems in northeast India. It represents one of the few remaining patches of Assam’s once-contiguous evergreen forest. The isolation caused by surrounding human settlements and tea plantations has created challenges for gene flow among animal populations.
Efforts have been initiated by the Assam Forest Department, in collaboration with conservation organisations, to mitigate human–wildlife conflict, monitor species populations, and develop community awareness programmes. The sanctuary’s role in maintaining ecological connectivity and biodiversity in the Brahmaputra Valley is of immense conservation significance.

Threats and Challenges

Despite its protected status, the sanctuary faces several threats:

• Habitat fragmentation: The forest is surrounded by tea gardens, cutting off animal movement corridors.
• Encroachment: Expansion of human settlements and agriculture around the sanctuary.
• Poaching and illegal collection: Though limited, occasional poaching and extraction of forest products occur.
• Human–wildlife conflict: Gibbons and macaques often raid nearby crop fields, leading to local tensions.

Moreover, the sanctuary’s small size makes it particularly vulnerable to external disturbances, climate change impacts, and loss of genetic diversity.

Ecotourism and Research

Hollongapar Gibbon Sanctuary is gradually becoming a prominent ecotourism destination in Assam. The forest’s serenity, combined with the chance to observe gibbons in their natural habitat, attracts wildlife enthusiasts and researchers. Eco-guides from local villages assist in conducting guided nature trails and birdwatching tours.
Scientific research in the sanctuary focuses on primate behaviour, ecological monitoring, and forest regeneration. Continuous documentation by zoologists and conservationists contributes valuable data for future conservation planning.

Cultural and Ecological Significance

For the local Assamese and indigenous communities, the sanctuary is not only a biodiversity hotspot but also a part of their cultural landscape. The Hollong tree holds religious and ecological importance, symbolising strength and endurance. The calls of gibbons at dawn have become a familiar natural soundscape associated with this region.
Ecologically, the sanctuary acts as a carbon sink, aids in groundwater recharge, and supports pollination networks vital for the surrounding agricultural systems. Its existence is a reminder of the balance between biodiversity conservation and sustainable human development.

Future Prospects

Long-term conservation success for Hollongapar Gibbon Sanctuary depends on landscape-level management, including restoration of connecting corridors, community participation, and sustainable tourism practices. Enhanced research on forest dynamics, climate resilience, and wildlife corridors can help ensure the sanctuary’s viability as a biodiversity stronghold for generations to come.