Population Estimation of Golden Langurs UPSC

GOLDEN LANGUR

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Picture Courtesy: https://www.istockphoto.com/photo/gees-golden-langur-guwahati-assam-india-gm639211130-115077065

Context: The latest survey conducted by the Primate Research Centre NE India (PRCNE), Assam Forest Department, Bodoland Territorial Council, Salim Ali Centre for Ornithology and Natural History (SACON), and Conservation Himalayas, estimated the population of golden langurs in India to be around 7,396.

Key Highlights of the survey

The survey covered the Manas Biosphere Reserve and fragmented forests in the western part of Assam, the entire distribution range of the golden langur (Trachypithecus geei).
The survey applied the block count method; the golden langur habitat was divided into grids or blocks. Researchers survey each block to count the number of langurs present. This method is relatively simple and cost-effective.
The survey highlighted an unstable situation in the fragmented habitats, particularly due to the absence of non-breeding all-male bands.
Researchers recommended the need for corridor linkage among fragmented habitats through plantations and canopy bridges to mitigate potential threats faced by golden langurs from anthropogenic interactions.

About Golden Langur

The Golden Langur's habitat is restricted to a small region in western Assam, in the foothills of the Himalayas along the border with Bhutan.
The Golden Langur's coat is a beautiful golden colour, particularly in adult males, while females and juveniles tend to be a lighter golden or even buff colour.
They are known for their beautiful fur, which changes colour depending on the season. In the summer, their fur lightens to a creamy tone, which helps them to reflect heat and stay cool. In the winter, their fur darkens to a golden chestnut hue. This change is thought to provide them with better camouflage against predators, such as eagles and hawks, which are more active during the colder months.
Males are larger and heavier than females, with broader chests and thicker fur on their shoulders and rumps. This difference in size is likely due to a combination of factors, including competition among males for mates and dominance within the troop.
They are primarily herbivores, meaning their diet consists mainly of plant matter. Their typical menu includes leaves, flowers, fruits, seeds, and buds. They are particularly fond of figs, which make up a significant portion of their diet in some seasons.
The International Union for the Conservation of Nature (IUCN) Red List of Threatened Species classifies the Golden Langur as endangered.

PRACTICE QUESTION

Q. Consider the following statements in the context of the Golden Langur:

1. They are found in the Western Ghat.

2. Their fur changes colour seasonally.

3. Males are larger and heavier than females.

4. They are primarily herbivorous.

5. They are classified as critically endangered by the IUCN Red List.

How many of the above statements are correct?

A) Only two

B) Only three

C) Only four

D) All five

Answer: B

Statement 1 is incorrect: Golden Langurs are found in a small region of Assam and the neighbouring foothills of the Black Mountains of Bhutan, not the Western Ghats.

Statement 2 is correct: The fur of the Golden Langur changes colour seasonally. In the winter, it's a dark golden chestnut, and in the summer, it's more cream-coloured.

Statement 3 is correct: Males are larger and heavier than females. Males can weigh up to 26 pounds (12 kg) and have a longer tails than females.

Statement 4 is correct: Golden Langurs are primarily herbivores, meaning they mainly eat leaves, fruits, seeds, buds, and flowers.

Statement 5 is incorrect: Golden Langurs are classified as endangered by the IUCN Red List due to habitat loss and fragmentation.