Altitude decides simian attitude to diet

Differing elevations of habitation make one group of Himalayan Gray Langur prefer fruits and another group relish flowers, says a study published in  Journal of Threatened Taxa

November 12, 2022 03:01 am | Updated 03:01 am IST - GUWAHATI

The Himalayan Gray Langur or Chamba Sacred Langur. Photo: Special Arrangement

The Himalayan Gray Langur or Chamba Sacred Langur. Photo: Special Arrangement

Differences in altitude make a primate species in the same Himalayan habitat choose between flowers and fruits as food options beyond their staple menu of leaves, a new study has revealed.

The Himalayan Gray Langur or the Chamba Sacred Langur ( Semnopithecus ajax) is a colobine, meaning leaf-eating monkey. It is considered an endangered species globally as its population is estimated to be less than 1,500 mature individuals in 15-20 groups.


Himalayan Gray Langur (Male)

Himalayan Gray Langur (Male) | Photo Credit: Special Arrangement

Three primatologists studied the diet composition of five such groups in and around the Kalatop-Khajjiar Wildlife Sanctuary in Himachal Pradesh between September and November 2020. They especially concentrated on two groups, one inhabiting the Kalatop forest at an average altitude of 2,396 metres, and the other based in the Khajjiar forest at an average altitude of 2,188 metres.

The domains of the two groups were only 208 metres apart, but the altitudinal gap made a huge difference when the monkeys took a break from feeding on the leaves of some 20 species of plants, primarily the Himalayan ivy ( Hedera nepalensis) and the Himalayan oak ( Quercus oblongata).


Himalayan Gray Langur (Female)

Himalayan Gray Langur (Female) | Photo Credit: Special Arrangement

While the Kalatop group satisfied their craving for something different by feeding on flowers, the Khajjiar group ate fruits for a change of taste. Flowers and fruits constituted 11.11% and 15.49% of the diet of the two groups respectively.

The preference for fruits or flowers “may depend upon the difference in their distribution in terms of elevation and availability of a particular plant part”, said the study published in the Journal of Threatened Taxa.


Himalayan Gray Langur or Chamba Sacred Langur

Himalayan Gray Langur or Chamba Sacred Langur | Photo Credit: Special Arrangement

The study was conducted by Rupali Thakur and Kranti Yardi of the Pune-based Bharati Vidyapeeth Institute of Environment Education and Research, and P. Vishal Ahuja of the Wildlife Information Liaison Department and Zoo Outreach Organisation based at Hardaspura in Himachal Pradesh’s Chamba district.

Apart from recommending a census for the Himalayan Gray Langur in the district, the trio of scientists advocated a further long-term study for a comparison of the diet and behaviour in the forested groups and the urbanised groups of this primate species. “This can help formulate specific conservation action for both the groups,” they said.


Himalayan Gray Langur or Chamba Sacred Langur

Himalayan Gray Langur or Chamba Sacred Langur | Photo Credit: Special Arrangement

The Himalayan Gray Langur was once considered a sub-species of the Semnopithecus entellus, commonly known as the Bengal Sacred Langur or Hanuman Langur, but it was separated as a species in 2005.

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