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Summary
- Western hoolock gibbons (Hoolock hoolock) are present in Assam.
- The population size is unknown.
- The gibbon population trend is decreasing.
- The site has a total size of 78,438 km².
- Key threats to gibbons are habitat encroachment and illegal logging.
- Conservation activities include education and awareness raising, and supporting communities near forests with alternative income sources such as beekeeping and mushroom cultivation.
Site_characteristics
The state of Assam is located in northeast India and comprises two global biodiversity hotspots: the Indo-Burma and the Himalayan hotspots (Mazumder 2014). The region is a stronghold for 12 primate species: Bengal slow loris Nycticebus bengalensis, Rhesus macaque Macaca mulatta, Assamese macaque Macaca assamensis, pig-tailed macaque Macaca leonina, stump-tailed macaque Macaca arctoides, Tibetan macaque Macaca thibetana, white-cheeked macaque Macaca luecogenys, capped langur Trachypithecus pileatus, golden langur Trachypithecus geei, Phayre’s langur Trachypithecus phayrei, western hoolock gibbon Hoolock hoolock, and eastern hoolock gibbon Hoolock leuconedys (Chetry et al. 2021).
Table 1. Basic site information for Assam
| Species | Hoolock hoolock |
| Area | 78,438 km² |
| Coordinates | 25.521581, 93.051847 |
| Type of site | Unclassified |
| Habitat types | Subtropical/tropical moist lowland forest |
| Type of governance |
Ape_status
In 2009, Chetry et al. (2012) recorded 33 gibbons in 10 groups based on direct sightings in the reserve forests of Hal logaon, Kukurmara, and Kundil Kalia (Chetry et al. 2021). In 2019, 17 individuals in seven groups in these three reserve forests were recorded, indicating a 48.5% population decline. The number of groups was also reduced from 26 (direct observations and call-count) in 2009 to 11 in 2019 (Chetry et al. 2021). In this time frame there was also a 18.75% increase in the proportion of adults to immatures, indicating reduced recruitment and population decline (Chetry et al. 2021).
Table 2. Ape population estimates reported for Assam
| Hoolock hoolock | 2019 | 17 | 7 | NA | Sadiya subdivision, 789.95 km² | Line transects (Distance) | Chetry et al. 2019 | Survey effort 98 km. Average group size was 2.42 | NA |
| Hoolock hoolock | 2017-2018 | NA | NA | NA | Upper Brahmaputra Valley, 9851 km² | Unknown | Sarma et al. 2021 | NA | NA |
Threats
Habitat encroachment and selective illegal logging represent the most severe threats to gibbons and other wildlife in Assam (Chetry et al. 2021).
Table 3. Threats to apes reported for Assam
| Category | Specific threats | Threat level | Description | Year of threat |
|---|---|---|---|---|
| 1 Residential & commercial development | 1.1 Residential areas | High | Habitat encroachment due to development activities and expansion of human settlements (Chetry et al. 2021, Chetry pers. comm. 2023). | Ongoing (2023) |
| 2 Agriculture & aquaculture | 2.1 Annual & perennial non-timber crops | High | Encroachment due to expansion of land for agriculture, including ginger and orange cultivation (Chetry et al. 2021, Chetry pers. comm. 2023). Jhum cultivation (a slash-and-burn type of shifting cultivation) has devastated large forest covers through the creation of canopy gaps and depletion of food (Mazumder 2014). | Ongoing (2023) |
| 2.3 Livestock farming & ranching | Present, but threat severity unknown | Livestock grazing (Chetry et al. 2021, Chetry pers. comm. 2023). | Ongoing (2023) | |
| 3 Energy production & mining | 3.2 Mining & quarrying | Present, but threat severity unknown | Coal mining (Chetry pers. comm. 2023). | Ongoing (2023) |
| 4 Transportation & service corridors | 4.1 Roads & railroads | High | Expansion of roads and railroads cause habitat fragmentation and further encroachment (Chetry pers. comm. 2023). | Ongoing (2023) |
| 5 Biological resource use | 5.1 Hunting & collecting terrestrial animals | Present, but threat severity unknown | In certain places in southern Assam poachers specifically hunt these primates for their skin, hides, bones, skull, etc. (Mazumder 2014). Hunting is ongoing in remote areas of Assam (Chetry pers. comm. 2023). | Ongoing (2023) |
| 5.2 Gathering terrestrial plants | Present, but threat severity unknown | Exploitation of non-timber forest products such as cane bamboo and ferns (Chetry et al. 2021). | Ongoing (2021) | |
| 5.3 Logging & wood harvesting | High | Illegal logging of certain species, including Uriam Bischoffia javanica, Simalu Bombax ceiba, Halakh Termina lia myriocarpa, and Titasopa Michelia champaca is causing canopy loss and creating fragments within the existing habitats. Exploitation for firewood has also been documented (Chertry et al. 2021). Illegal logging is ongoing (Chetry pers. comm. 2023). | Ongoing (2023) | |
| 6 Human intrusions & disturbance | Unknown | |||
| 7 Natural system modifications | 7.2 Dams & water management/use | Unknown | Hydroelectric projects are planned in the area (Chetry pers. comm. 2023). | Ongoing (2023) |
| 8 Invasive & other problematic species, genes & diseases | Unknown | |||
| 9 Pollution | Unknown | |||
| 10 Geological events | Absent | |||
| 11 Climate change & severe weather | Unknown | |||
| 12 Other threat | Absent |
Conservation_activities
Table 4. Conservation activities reported for Assam
| Category | Specific activity | Description | Implementing organization(s) | Year of activity |
|---|---|---|---|---|
| 2 Counter-wildlife crime | 2.3 Conduct regular anti-poaching patrols | Forest department conducts patrols in protected areas in the state of Assam (Chetry pers. comm. 2023). | Ongoing (2023) | |
| 4 Education & awareness | 4.1 Educate local communities about apes and sustainable use | NGO Aaranyak organizes talks in schools and universities and promotes visits to sanctuaries to see gibbons (Chetry pers. comm. 2023). | Ongoing (2023) | |
| 7 Economic & other incentives | 7.2 Provide non-monetary benefits to local communities for sustainably managing their forest and its wildlife (e.g., better education, infrastructure development) | Aaranyak supports alternative income generation through the distribution of handlooms, beekeeping and mushroom cultivation training, as well as poultry and ducks (Chetry pers. comm. 2023). | Ongoing (2023) |
Challenges
Lack of long-term funding for continuity of conservation activities and lack of a national gibbon action plan, which exists for other endangered species in the country, but not for gibbons (Chetry pers. comm. 2023).
Table 5. Challenges reported for Assam
| Challenges | Specific challenges | Year(s) | Source |
|---|---|---|---|
| Lack of long-term funding | Chetry pers. comm. 2023 | ||
| Lack of national action plan | Chetry pers. comm. 2023 |
Research_activities
Multiple studies have been conducted in Assam to investigate the status of gibbons and other primates present in the area (Chetry et al. 2021, Kakati et al. 2009, Choudhury 2009, Sarma et al. 2021).
Documented behaviours
Table 7. Behaviours documented for Assam
| Behavior | Source |
|---|---|
| Not reported |
Exposure to climate change impacts
External links
Relevant datasets
References
Chetry, D., Phukan, M., Chetry, S., Baruah, B., Deka, J. R., Das, A. K., ... & Bhattacharjee, P. C. (2021). The Eastern Hoolock Gibbon Hoolock leuconedys Population in Assam, India, is on the Verge of Extinction. Primate Conservation, (35).https://doi.org/10.13140/RG.2.2.26187.52005
Choudhury, A. (2009). The distribution, status and conservation of hoolock gibbon, Hoolock hoolock, in Karbi Anglong district, Assam, Northeast India. Primate Conservation, 24(1), 117-126.
Kakati, K., Raghavan, R., Chellam, R., Qureshi, Q., & Chivers, D. J. (2009). Status of Western Hoolock Gibbon (Hoolock hoolock) populations in fragmented forests of eastern Assam. Primate Conservation, 24(1), 127-137.
Mazumder, M. K. (2014). Diversity, habitat preferences, and conservation of the primates of southern Assam, India: The story of a primate paradise. Journal of Asia-Pacific Biodiversity, 7(4), 347-354.https://doi.org/10.1016/j.japb.2014.10.001
Sarma, K., Saikia, M. K., Sarania, B., Basumatary, H., Baruah, S. S., Saikia, B. P., ... & Saikia, P. K. (2021). Habitat monitoring and conservation prioritization of Western Hoolock Gibbon in upper Brahmaputra Valley, Assam, India. Scientific reports, 11(1), 1-11. https://doi.org/10.1038/s41598-021-94844-8
Page completed by: Dilip Chetry & A.P.E.S. Wiki team Date: 04/10/2023