With respect to the Western Hoolock Gibbons, which of the following statements is/are correct?

Question

With respect to the Western Hoolock Gibbons, which of the following statements is/are correct?

1. A Sanctuary in North-east India is home to this ape species listed as Endangered in the International Union for Conservation of Nature (IUCN) Red List.

2. They have specialized brachiation and can easily swing between trees.

3. They possess a strong and heavy build like gorillas, yet are remarkably agile tree climbers.

1. A. 1 only
2. B. 1 and 2 (Correct answer)
3. C. 2 and 3
4. D. 3 only

Correct Answer

Option B — B

Detailed Solution & Explanation

The correct answer is Option B.

Key Points

• Statement 1 is correct: the Western Hoolock Gibbon is listed as Endangered on the IUCN Red List, and the Hoollongapar Gibbon Sanctuary in Jorhat district, Assam, is dedicated to it.
• It is India's ONLY ape — every other Indian primate is a monkey, langur or loris.
• Statement 2 is correct: gibbons are specialised brachiators.
• Brachiation is arm-over-arm swinging locomotion, supported by their exceptionally long arms, hook-like hands and a rotating shoulder joint.
• They are the fastest and most agile of all tree-dwelling, non-flying mammals.
• Statement 3 is incorrect, and is the key to the question: gibbons are light and slender, typically 6–9 kg — nothing like the heavy build of a gorilla.
• Gibbons are 'lesser apes'; gorillas, chimpanzees, orangutans and bonobos are the 'great apes'.
• Their light frame is precisely what makes brachiation possible.
• Additional context: in India the species is found south of the Brahmaputra and east of the Dibang river.
• Its main threats are habitat fragmentation — gibbons will not cross open ground, so a road or a tea garden can isolate a population permanently.
• Canopy bridges are used as a mitigation measure.