IAS Gyan

Daily News Analysis


2nd September, 2023 Environment

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  • The New Delhi Municipal Council (NDMC) has put up cut outs of hanuman langurs (Semnopithecus entellus) to deter rhesus macaques (Macaca mulatta), ahead of the G20 Summit in the national capital next week.


Scientific Basis

  • The scientific basis for using langur cutouts and sounds to deter rhesus macaques is questionable.
  • There is evidence from scientific observations that langurs and rhesus macaques do not necessarily have an adversarial relationship in their natural habitat.
  • Research has shown instances of peaceful coexistence, even playful interactions, between the two species.

Ethical Considerations

  • The use of langur cutouts and simulated monkey sounds to deter rhesus macaques raises ethical concerns. It can be seen as a form of harassment or disturbance to both species.
  • While the intention may be to manage conflicts between humans and macaques, it is important to consider the well-being of the animals involved.
  • Such measures could cause stress or confusion among the monkeys and may not be a humane solution.

Legal Implications

  • Such actions may be in violation of the Wild Life (Protection) Act, 1972, which aims to protect wildlife and their habitats. Using langur cutouts and sounds to manipulate the behavior of these animals may not align with the principles of wildlife conservation and protection.

Alternative Solutions

  • Wildlife experts suggest that addressing the root causes of human-macaque conflicts, such as improper disposal of food waste or feeding of wildlife, would be a more effective and ethical approach.
  • Educating the public about responsible behavior around wildlife and implementing measures to reduce human-macaque interactions can lead to more sustainable solutions.


  • Langurs and rhesus macaques are two distinct groups of primates, both belonging to the family Cercopithecidae.
  • They share common characteristics as Old World monkeys but have some notable differences in terms of behavior, habitat, and physical traits.


  • Langurs are a group of Old World monkeys native to Asia, known for their distinctive appearance and social behavior.
  • There are several species and subspecies of langurs, including the Gray Langur, Hanuman Langur, and the Purple-faced Langur.

Physical Characteristics

Coloration: Langurs are typically gray or black in color, although some species may have white markings on their face or body.

Tail: They have long, slender tails that can measure as long as their bodies, often used for balance.

Face: Langurs have a relatively flat face with a narrow, pointed nose.

Eyes: Their eyes are relatively large, adapted for good vision.


  • Langurs are primarily arboreal, which means they live in trees.
  • Their habitat ranges from tropical and subtropical forests to mountainous regions.
  • Some species are adapted to different altitudes and climates, allowing them to occupy a variety of niches.

Behavior and Social Structure

Group Living: Langurs are highly social animals and live in groups called troops, which can consist of several individuals, including males, females, and young. These troops are organized around a dominant male.

Feeding: They are primarily herbivorous, feeding on leaves, fruits, and other plant material. Their complex stomachs help them digest tough plant fibers.

Communication: Langurs communicate through vocalizations, body language, and grooming. They have a wide range of vocalizations used for various purposes, such as warning of predators or maintaining group cohesion.


Langurs typically have a single offspring, although twins can occur occasionally. The gestation period is about 6-7 months. Young langurs are cared for by the entire troop, not just their mothers.

Conservation Status

The conservation status of langurs varies among species. Some are classified as vulnerable or endangered due to habitat loss and hunting for their fur or body parts.

Rhesus Macaques

  • Rhesus macaques are another group of Old World monkeys native to South Asia.
  • They are one of the most widely studied non-human primates and have several subspecies, including the Indian rhesus macaque and the Chinese rhesus macaque.

Physical Characteristics

Coloration: Rhesus macaques typically have brown or grayish fur with a pinkish face.

Tail: They have a relatively short tail compared to langurs.

Face: Their faces are rounder and less pointed compared to langurs.

Eyes: Rhesus macaques have distinctive red or brown eyes.


Rhesus macaques are highly adaptable and can be found in a wide range of habitats, including forests, grasslands, and urban areas. They are known for their ability to thrive in human-altered environments.

Behavior and Social Structure

Group Living: Like langurs, rhesus macaques are social animals and live in troops with a hierarchical structure. The dominant male leads the troop.

Feeding: Rhesus macaques are omnivorous and eat a varied diet, including fruits, leaves, insects, and small vertebrates.

Communication: They communicate using a combination of vocalizations, facial expressions, and body postures.


Female rhesus macaques have a menstrual cycle similar to humans. They typically give birth to a single offspring, with a gestation period of about 165-180 days. Young macaques are cared for by their mothers and other troop members.

Conservation Status

Rhesus macaques are listed as a species of "Least Concern" by the International Union for Conservation of Nature (IUCN). Their adaptability to various environments has contributed to their stable population.


The scientific evidence suggests that langurs and rhesus macaques can coexist peacefully in their natural habitats, challenging the assumption that langur cutouts and sounds are an effective means of deterring macaques. It is crucial to consider ethical and legal implications and explore alternative, science-based approaches to manage human-macaque conflicts while respecting the welfare of these animals.


Q. Which of the following statements is/are correct?

1. Langurs (Semnopithecus entellus) are always aggressive towards rhesus macaques (Macaca mulatta).

2. Langurs and rhesus macaques often groom each other in the wild.

3. Rhesus macaques are larger in size than langurs.


A) Only Statement 1 is true.

B) Only Statement 2 is true.

C) Only Statement 3 is true.

D) Statements 2 and 3 are true.

Answer: B)