Investigating Anthropogenic and Social Influences on Diet of Semi-Urban Vervet Monkeys Using DNA Metabarcoding

With increasing human domination of ecosystems, wildlife must either relocate or adapt its behaviour to anthropogenic impacts in order to survive. Vervet monkeys (Chlorocebus pygerythrus), whose natural habitats have been progressively encroached upon by urban expansion, have successfully adapted to urbanised environments because of their flexible and generalist feeding behaviour. Characterising diet composition of vervet monkeys can therefore reveal how they exploit anthropogenic resources and uncover opportunistic foraging behaviours. However, accurately determining complete diets through direct observations is challenging. In this study, we used an environmental DNA (eDNA) approach investigating the DNA mixtures present in faecal samples as a non-invasive complementary method for assessing diet and foraging strategies. We identified the dietary components of vervet monkeys through DNA metabarcoding of 447 faecal samples collected from two monkey groups over 4 months in a semi-urban neighbourhood in South Africa. We further compared the results with observational data on foraging to describe how vervet monkeys exploit anthropogenic resources. Subsequently, we evaluated whether dietary patterns can be distinguished between groups and within matrilineal levels. We found DNA metabarcoding data to be consistent with observational data, but the former revealed a broader diversity of consumed taxa. Additionally, we detected a difference in diet between the two investigated groups, and a tendency for similar dietary patterns among matrilineal pairs compared to other group members. Our results support the use of the DNA metabarcoding methodology, both to determine the complex diet of omnivorous species in urbanised ecosystems and to address interindividual foraging behaviours.