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

Dishari Dasgupta,Arnab Banerjee,Aparajita Bhattacharya,Srijita Karmakar,Pritha Bhattacharjee,Purnendu Sardar,Rikita Karar,Swastika Ghosh,Manabi Paul,Shohini Mitra,Debolina Banerjee

doi:10.3389/fpsyg.2021.649027

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.

Highlights

The global urban human population is set to reach the 5 billion mark by 2028 (ONU, 2018), facilitating urban sprawling and subsequently contributing to natural habitat loss worldwide at an unprecedented rate
We have focused on the feeding preference of group-living, free-ranging gray langurs in the urban areas of West Bengal, India, which unraveled their behavioral plasticity to utilize anthropogenic habitats
Free-ranging gray langur groups were identified through regular census between September 2018 and December 2018 in various parts of West Bengal, India, of which three distinct langur groups [one in Dakshineswar (22.6573◦N, 88.3624◦E), one in Nangi (22.4973◦N, 88.2214◦E), and one in Sarenga, Nalpur (22.5307◦N, 88.1840◦E)] were selected for long-term observations, considering the various level of human interferences received by the gray langurs (Supplementary Data D1, D2)

Summary

Introduction

The global urban human population is set to reach the 5 billion mark by 2028 (ONU, 2018), facilitating urban sprawling and subsequently contributing to natural habitat loss worldwide at an unprecedented rate. Despite significant loss of biodiversity, urban expansion offers various high-calorie resource options to the generalist species who have higher dietary as well as foraging plasticity, and can adjust more readily to the altered habitat in contrast to the specialists (Vázquez and Simberloff, 2002; Fisher and Owens, 2004) Such anthropogenic food sources remain available throughout the year, providing a risky yet reliable and accessible resource option which is thought to be one of the major driving forces behind human-animal co-existence within urban settlements (Bateman and Fleming, 2012; Lowry et al, 2013; Widdows et al, 2015; Thabethe and Downs, 2018). Urban-dwelling free-ranging animals have been shown to acquire a preference toward anthropogenic food items to minimize their foraging activities, so that could invest more energy and time in nurturing social relationships which is essential to attain better fitness benefits (Saj et al, 1999; Hoffman and O’Riain, 2012; Sha and Hanya, 2013; Bryson-Morrison et al, 2016, 2017; Thatcher et al, 2019)

Methods

Results

Conclusion