City lizards are more social.

Abstract

Cities are expanding globally, exposing animals to novel ecological conditions that can alter the frequency and nature of their social interactions. Urban habitat features, such as built infrastructure and patchy resource distributions, can constrain movement and promote aggregation, potentially increasing encounters among conspecifics and introducing unique social challenges. Understanding how urbanization affects social behaviour is therefore crucial. However, these effects remain poorly understood, and studies on solitary or non-gregarious species are particularly scarce. Here, we investigate how urbanization influences social behaviour in the common wall lizard (Podarcis muralis), a territorial species and successful urban dweller. We constructed social networks using proximity-based association data from urban and non-urban lizard populations. Urban lizards had more social connections, stronger associations and were observed in more associations overall. These differences were not explained by variation in population density. We propose that spatial constraints and resource heterogeneity in urban habitats may enhance social tolerance. Our results reveal that urbanization can reshape social behaviour even in less gregarious species and suggest that shifts in social strategies may facilitate persistence in urban landscapes.