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Species in News: Hoolock Gibbon
Context:
The Northeast Frontier Railway (NFR) has allocated funds to construct canopy bridges to enable the hoolock gibbon to cross a railway track safely.
More on News:
- Decision made in consultation with Assam State Forest Department, Wildlife Institute of India (WII), and other stakeholders.
- Canopy bridges designed by WII in collaboration with NFR.
- Bridges to be constructed at identified points to facilitate gibbon movement between sanctuary halves divided by the Mariani-Dibrugarh railway track.
- The track is 1.65 km long and set to be doubled and electrified.
- The track divides the 2,098.62-hectare Hollongapar Gibbon Sanctuary in Jorhat district, Assam.
- The sanctuary hosts the largest concentration of the hoolock gibbon, one of the 20 species of apes on earth.
Canopy Bridges for Gibbons in Hollongapar Gibbon Sanctuary:
- The hoolock gibbon, known for its vocalisation, primarily inhabits the upper canopy of tall trees, particularly the hollong (Dipterocarpus macrocarpus).
- Fragmentation of the forest along the railway track has disrupted the arboreal nature of the gibbons, endangering them while crossing the track.
About Hoolock Gibbon:
- The hoolock gibbon is the only ape found in India.
- The hoolock gibbon, unique to Northeast India, is one of the 20 gibbon species globally.
- They are native eastern Bangladesh, Northeast India, Myanmar, and Southwest China.
- Adult males are black, females brown, with harsh voices.
- Western Hoolock Gibbon:
- Found in all states of north-east India.
- Range: South of the Brahmaputra river, east of the Dibang river.
- Outside India: Eastern Bangladesh and north-west Myanmar.
- Listed as Endangered on the IUCN Red List.
- Eastern Hoolock Gibbon:
- Inhabits specific pockets of Arunachal Pradesh and Assam in India.
- Outside India: Southern China and north-east Myanmar.
- Listed as Vulnerable on the IUCN Red List.
- Population Decline: Both species face population declines due to habitat destruction and hunting.
- Western hoolock gibbons have declined by almost 90% over the last 30 years.
- Legal Protection:
- Listed on Schedule 1 of the Indian (Wildlife) Protection Act 1972.
- Hoollongapar Reserve Forest upgraded to Gibbon Wildlife Sanctuary in 1997.
Classification & Specifications Of Gibbon:
- Common Name: Gibbons
- Scientific Name: Hylobatidae
- Type: Mammals
- Diet: Omnivore
- Group Name: Family
- Average lifespan in wild: Up to 25 years
- Gibbons are acrobatic, tree-dwelling primates.
- Unlike most other primates, gibbons often form long-term bonds and sometimes mate for life.
- A primate is any mammal of the group that includes lemurs, lorises, tarsiers, monkeys, apes, and humans.
- Lack higher cognitive abilities and self-awareness compared to great apes.
- Physical features:
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- They have long limbs that allow them to swing through trees.
- Gibbons lack tails.
- They have long, dense hair that ranges in colour from cream to black.
- Gibbons are very social animals.
- Size: Smaller species: 40–65 cm (16–26 inches) in head and body length, 5.5 kg (12 pounds).
- Larger species: Up to 90 cm (35 inches), with the female siamang weighing 10.5 kg (23 pounds) and the male 12 kg (26 pounds).
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- Vocalisation:
- Loud, musical voices that carry over long distances.
- Characteristic “great call” duet, used as a territorial marker.
- Genera: Hoolock, Hylobates, Nomascus, Symphalangus.
- Vocalisation:
- Adaptations and Behavior:
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- Movement: Arboreal, brachiating (swinging from arms) for rapid movement.
- Walk erect with arms held aloft or behind when on the ground.
- Activity: Diurnal, living in small monogamous groups that defend territories.
- Diet: Primarily fruit, with some leaves, insects, bird eggs, and young birds.
- Reproduction: Single offspring born after seven months’ gestation.
- Offspring mature in seven years.
- Movement: Arboreal, brachiating (swinging from arms) for rapid movement.
- Distribution: Widely distributed in rainforests and monsoon forests of Southeast Asia.
