In cities, animals are pushed closer together than in nature. This cramped coexistence also affects their behavior – for example in the case of wall lizards, as a study now shows. Exemplies that live in the city therefore have more social contacts than fellow species living in the country. Instead of fighting each other, the “townspeople” live together peacefully. This change of strategy could ultimately have more of the limited resources in the city.
The habitat for many animal species disappears through urbanization. As a result, people often live side by side with animals that are forced to push into the cities. However, some species also draw advantages, including the wall lizard. It is considered a typical cultural successor who follows people in their artificial habitat and lives there, for example, on rail and road embankments. In the city, however, buildings and unevenly distributed resources can limit the movement options of the reptiles. This can make it happen that they “collect” in certain places and meet more often on fellow species.
Eidechs encounters under the magnifying glass
A research team around Avery Maune from the University of Bielefeld has now examined how this influenced the social life of the lizards. For this purpose, the researchers in the city of Rovinj and in the Zlatni RT forest park followed living wall lizards in Croatia, which they numbered with adhesive tape. Over 21 days, they watched a total of 94 different lizards twice a day and recorded their social contacts.
There was an encounter as a contact when two of the animals were within two meters without an obstacle between them. Only peaceful activities such as sun or food search were considered contact – battles and mating behavior were not taken into account. Subsequently, Maune and her colleagues used a social network analysis – a procedure that is normally used in behavioral research in humans – to evaluate the social relationships of the lizard.
From combative loner to a social being
The results show a clear difference between the contacts of city and land lizards: While 81 percent of the wall lizards observed in the city met at least once in the three weeks, this was only the case in 23 percent of the country-living individuals. The “townspeople” also had significantly more social contacts: they had an average of 1.9 contacts, while their peers only had 0.3 in the forest park.
“Our results show that wall lizards in cities maintain significantly more contacts and build more stable bonds than their conspecifics in natural areas,” explains Maune. “This is remarkable because these lizards are usually very territorial and are more likely to avoid.” But why are the reptiles living in the city more sociable?
Maune and her colleagues explain this primarily with the structure of the city: In cities, important things such as food, hiding places and sunplaces are irregularly distributed and concentrated for the animals. Then it is less worthwhile for the lizards to aggressively defend these resources – a peaceful coexistence is more advantageous. “The ability to develop new social strategies could be crucial so that species exist in urban habitats,” explains the biologist.
Source: Avery Maune (Bielefeld University) et al., Biology Letters, DOI: 10.1098/RSBL.2025.0326