Why are city animals so cheeky

A new study has found that urban animals in different countries are indeed more likely to be bolder, more active and more willing to explore new things than their relatives from less urbanised areas. The scientists combined data from 80 papers from 28 countries and compared the behaviour of 133 species - birds, mammals, amphibians, reptiles and insects.

Important: it's not about the city "spoiling" animals or making them meaner in the human sense. The researchers studied specific behavioural traits - boldness, aggressiveness, activity and exploratory behaviour. The most consistent result was specifically related to a greater willingness to take risks around humans.

Details

The authors of the paper conducted a global meta-analysis. This means that they did not observe one city or one species, but collected the results of already published studies and saw if there was a common pattern. The analysis included comparisons of urban and non-urban populations of the same species: for example, how birds, mammals or insects behave in and out of the city.

The scientists focused on four behavioural traits. Boldness - how willing the animal is to approach a person or source of risk. Aggressiveness - how it reacts to competitors or a threat. Activity - how much and how actively it moves. Exploratory behaviour - how willingly it tries new things and explores unfamiliar environments. For all of these traits, urban populations differed on average from non-urban populations.

The main conclusion is that animals that live in cities are more likely to be bolder. This makes sense: urban environments are noisy, dense, and full of people, cars, artificial light, rubbish, new food sources, and unexpected obstacles. To survive in such an environment, it may be more advantageous for an animal to get used to humans more quickly and take more risks.

But there are two possible reasons here. On the one hand, the city may select for bolder individuals: the cautious ones are simply less likely to survive or not stay in the urban environment. On the other hand, animals may change their behaviour over the course of their lives as they get used to people and urban environments. It is likely that both mechanisms are at work in different species.

The authors emphasise that the data are strongest for birds. More than 70% of the studies in the analysis involved birds, while insects, amphibians and reptiles together accounted for about 10% of the data. Therefore, the conclusions for birds are more reliable, while there are fewer studies on other animal groups.

An important detail: it's not just about familiar urban species like pigeons, gulls, rats or mice. The researchers note that similar shifts are seen in species that are usually associated with rural or natural habitats, but are increasingly adapting to cities.

Why it matters

Urban animals are more than just a backdrop to our daily lives. They live alongside humans, use our waste, parks, buildings, roads and sometimes come into conflict with us. If animals become bolder and less avoidant of humans, these contacts may occur more frequently.

This can be a problem for both humans and the animals themselves. Bolder animals are more likely to approach people, cars, rubbish bins and pets. This increases the risk of collisions, injuries, conflicts and, in some cases, transmission of infections between wild animals, pets and humans. The researchers explicitly point to a possible increase in the risk of conflict and zoonotic transmission, although this does not mean that every urban animal is dangerous.

For urban planning, it's also important. If cities expand, animals will inevitably live near people more and more. So, when designing parks, courtyards, green corridors and waterfronts, it's worth considering not only the presence of animals, but also how the city changes their behaviour.

Background

The city is a challenging environment for wildlife. There is less natural habitat, more noise and light, denser development, more people and traffic. But at the same time the city provides new opportunities: food from waste, shelter in buildings, warmer microclimate, fewer of some predators.

That's why some species disappear from cities, and others, on the contrary, quickly adapt. Crows, pigeons, seagulls, rats, foxes, raccoons, squirrels and many other animals learn to use urban resources. Their "cheekiness" is often not a whim, but the result of living in an environment where caution is not always advantageous.

The new study is important because it gathers disparate observations into one picture. Previously, scientists have studied individual species or individual cities extensively. Now the analysis shows: similar behavioural changes are found in different parts of the world and in different groups of animals.

Source

Tracy T. Burkhard, Ned A. Dochtermann, Anne Charmantier, "Global meta-analysis reveals urban-associated behavioural differences among wild populations", Journal of Animal Ecology, 2026. DOI: 10.1111/1365-2656.70269. The study is published in the Journal of Animal Ecology, a journal of the British Ecological Society.

In the paper, the authors combined data from 80 studies from 28 countries and compared urban and non-urban populations of 133 animal species. The analysis showed that urban animals on average showed more pronounced boldness, aggressiveness, activity and exploratory behaviour. However, the data are unevenly distributed, with the most studies focusing on birds, while amphibians, reptiles and insects are much less well studied.