Altered Food Habits? Understanding the Feeding Preference of Free-Ranging Gray Langurs Within an Urban Settlement

Abstract

Urbanization affects concurrent human-animal interactions as a result of altered resource availability and land use pattern, which leads to considerable ecological consequences. While some animals have lost their habitat due to urban encroachment, few of them managed to survive within the urban ecosystem by altering their natural behavioral patterns. The feeding repertoire of folivorous colobines, such as gray langur, largely consists of plant parts. However, these free-ranging langurs tend to be attuned to the processed high-calorie food sources to attain maximum benefits within the concrete jungle having insignificant greenery. Therefore, besides understanding their population dynamics, the effective management of these urbanized, free-ranging, non-human primate populations also depends on their altered feeding habits. Here, we have used a field-based experimental setup that allows gray langurs to choose between processed and unprocessed food options, being independent of any inter-specific conflicts over resources due to food scarcity. The multinomial logit model reveals the choice-based decision-making of these free-ranging gray langurs in an urban settlement of West Bengal, India, where they have not only learned to recognize the human-provisioned processed food items as an alternative food source but also shown a keen interest in it. However, such a mismatch between the generalized feeding behavior of folivorous colobines and their specialized gut physiology reminds us of Liem's paradox and demands considerable scientific attention. While urbanization imposes tremendous survival challenges to these animals, it also opens up for various alternative options for surviving in close proximity to humans which is reflected in this study, and could guide us for the establishment of a sustainable urban ecosystem in the future.

Left or right: Handedness in free-ranging Hanuman langurs (Semnopithecus entellus) residing in an urban ecosystem

“…These DG langurs, who lost their natural home due to urban sprawling, have learned to survive within human-modified ecosystems. These langurs are largely dependent on human-provisioned food items and considerably interacted with pilgrims (Dasgupta et al 2021). Owing to their high interactions with humans this troop spends a significant amount of their time on the ground (Dasgupta et al, manuscript in preparation), making this troop more terrestrial rather than arboreal.…”

“…Among these three locations, Dakshineswar has been considered as an urban landscape having ~ 77 percentage of built-up area in contrast to Nangi and Kurumba (built up area ~ 23.31 % and ~ 10.63% respectively) ( Figure 1 ). Besides, langur troop in Dakshineswar (DG) receive notable human attention because of their deity values, and are frequently observed to extend their hands to receive human-offered food items (Dasgupta et al 2021; Dasgupta et al, manuscript in preparation).…”

“…For each experiment, we have used a transparent bottle with a height of 18 cm and a diameter of 22 cm, which has been baited with a food item. As buns are easily available and one of the preferred food items of these DG langurs (Dasgupta et al, 2021), here, we have used them as bait and kept inside the bottle in the absence of focal langurs ( Figure 2, Panel I ). For each trial, the observers position themselves with the bottle in front of the subject (individual langur, randomly selected for the experiment), so that the bottle is at equidistance from both the hands of the subject ( Figure 2 , Panel II , ESM Video clip).…”

Eating smart: Free-ranging dogs follow an optimal foraging strategy while scavenging in groups

“…Animals living in urban habitats often face new challenges, apart from stochasticity in resources, in the form of novel, anthropogenic food and scarcity of their natural food. One way in which urban animals adapt to this challenge is by diet-switching, a foraging behaviour wherein the animal starts consuming an alternative food/prey when the primary food is scarce in number (Dasgupta et al, 2021;Sarkar and Bhadra, 2022).…”

Determinants of Grooming Behavior in Captive Langurs under Human Disturbance: A Case Study from the Central Zoo, Kathmandu, Nepal

“…Hanuman/ Himalayan langurs (Semnopithecus sp.) are shy, folivores and canopy dwellers living in multimale-multifemale social groups in the wild (Kavana et al, 2015;Khanal et al, 2018;Dasgupta et al, 2021). Behavioral studies in langurs have been carried out in the wild but are rarely studied in captive conditions.…”