Blog One: Northern Plains Gray Langur

 Semnopithecus entellus: Northern Plains Gray Langur 
Nicole Anguiano-Garcia

Taxonomy:

The Northern Plains Gray Langur(Semnopithecus entellus) is a primate within the Haplorhini suborder. They belong to the infraorder Catarrhines, the superfamily Cercopithecidae, also known as “Old World Monkeys,” and the Colobinae subfamily, or the “Leaf-Monkeys.” The Colobinae subfamily consist of 7 genera with 55 different species and over 40 subspecies (Botting, 2019). However this blog solely focuses on Semnopithecus entellus. Northern Plains Gray Langurs are also called “Hanuman langurs” or “sacred langurs” due to their connection with the Hindu god, Lord Hanuman. In Hinduism, the monkey god Hanuman is a symbol of strength and bravery, and therefore the reason why the Northern Plains Gray Langur is generally left undisturbed (Ebersole, 2003).

Primate taxonomy. Note the box that corresponds to the Colobinae subfamily. Created by Tori Saneda. 

Lord Hanuman. Picture from Mohanjichronicles.com. 

 

Morphology: 

Northern Plains Gray Langurs have brown-gray fur, their face, hands, feet, and ears are black, and have a lion-like mane with white fur framing their face. This species of langur does show some sexual dimorphism, with males being slightly larger than females. Without including their tails, which are longer than their bodies, males average a length of 64 cm, while females average a length of 58.5 cm. Male Northern Plains Gray Langurs tails are about 91 cm long and female Northern Plains Gray Langurs tails are about 86 cm (Semke, 2011). 

Scale Comparison between Average U.S. Male and Female Height and Average Male and Female Gray Langur Height. Created on HeightComparison.com   

As their subfamily name suggests, Northern Plains Gray Langurs have a primarily folivorous diet, which is evident from their 2.1.2.3 dental formula, their small incisors, and their high, sharp molars with shearing crests. Besides leaves, which make up about 52-61% of their diet, Northern Plains Gray Langurs also consume fruit, insects, and other foods such as gum, bark, and soil (Semke, 2011). 

 Northern Plains Gray Langurs have about equal size arms and legs, partaking in quadruped locomotion. Their long tails help them stay balanced while climbing and leaping trees, where they spend about 20% of their time, especially during the night as they are diurnal (Botting, 2019).

Life History:

When in captivity, Northern Plains Gray Langurs can live up well into their thirties. In the wild however, males tend to live up to 18 years old and females to 30 years old (Gron, 2008). 

Regarding reproduction, Northern Plains Gray Langurs tend to be either polygynous, where males have more than one female partner, or polyandrous, where females have more than one male partner. Males who do not have any partners create bachelor groups. Mating occurs between the months of July and October. Females gain male attention by head shaking and showing their anogenital region. Once pregnant, gestation lasts for about 212 days, where mating continues to prevent infanticide by dominant males (Semke, 2011). 

When it comes to ranking within Northern Plains Gray Langurs, males gain dominance through fighting, whereas females obtain higher ranking by sexually maturing faster, though their rank typically decreases with age. Females reach sexual maturity at around 3 years, while males at around 5 years (Semke, 2011). 

Once females finish gestation, typically only one infant is born. The first week of an infant’s life is spent with their mothers, though quickly after, they are cared for by other females who recently gave birth (Fleagle, 2013). Weaning does not start until 8 months and is done by 13 months. By the time infants are about a year old, they only spend about 20% of their time with their mothers. By about 2 years of age, Northern Plains Gray Langurs are fully independent. Before the age of 5, when they reach sexual maturity, male Northern Plains Gray Langurs must leave their natal groups to find potential mates (Semke, 2011). 

Conservation Status: 

Northern Plains Gray Langurs occupy a large geographical area that spans throughout India and south of the Himalayas (Botting, 2019). 

Northern plains gray langur range. IUCN, 2021

As briefly mentioned in the Taxonomy section, due to their connection with the Hindu god, Lord Hanuman, Northern Plains Gray Langurs are typically left alone. In fact, the IUCN Red List has this species listed as “least concern.” As of 2008, there are approximately 300,000 Northern Plains Gray Langurs in the wild (Gron, 2008; Kumara et al., 2020). Although the Northern Plains Gray Langur is not endangered and considered sacred, it’s important to keep in mind that the species is experiencing habitat loss due to agriculture and deforestation. However, a study conducted in 2012 by Khatun et al., found that local communities in Keshabpur, Bangladesh had positive attitudes towards langur conservation, which may help mitigate these threats. 

Works Cited:

Botting, J. (2019). Northern Plains Gray Langur: Semnopithecus entellus. New England Primate Conservancy. https://neprimateconservancy.org/northern-plains-gray-langur/

Ebersole, R. (2003). Monkeys From Heaven. National Wildlife Federation. https://www.nwf.org/Magazines/National-Wildlife/2003/Monkeys-From-Heaven

Fleagle, G.J. (2013). Old World Monkeys. Primate Adaptation and Evolution (Third Edition), 119-150. https://doi.org/10.1016/B978-0-12-378632-6.00006-9

Gron, K. (2008). Primate Factsheets: Gray langur (Semnopithecus). Wisconsin National Primate Research Center. https://primate.wisc.edu/primate-info-net/pin-factsheets/pin-factsheet-gray-langur/

Khatun, H.U., Ahsan, F., & Røskaft, E. (2012). Attitudes of the local community towards the conservation of the common langur  (Semnopithecus entellus) in Keshabpur, Bangladesh. International Journal of Biodiversity and Conservation, 4(11), 385-399. DOI: 10.5897/IJBC12.035

   

Kumara, H.N., Kumar, A. & Singh, M. (2020). Semnopithecus entellus. The IUCN Red List of Threatened Species 2020: e.T39832A17942050. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T39832A17942050.en. 

Semke, R. (2011). Semnopithecus entellus: Hanuman langur. Animal Diversity Web. https://animaldiversity.org/accounts/Semnopithecus_entellus/