Effects of human presence and anthropogenic food availability on escape behaviour of hooded crows across urban landscape

Abstract

Urbanization is associated with a range of environmental changes that influence multiple behavioural traits of animals living in cities. Increased tolerance to humans is a common aspect of animal behaviour in urban environments, with animals typically allowing people to approach them more closely than in rural or natural areas. In this study, the effects of urbanization-related habitat features, such as pedestrian density, human population size, impervious surface area and food availability, on the escape behaviour of hooded crows, Corvus cornix, in Belgrade, Serbia, were investigated. Results show that crows’ tolerance to humans varied across urban areas depending on human population density, impervious surface area and the amount of human waste. Pedestrian and human population densities were significant negative predictors of alert distance and flight initiation distance but positive predictors of buffer distance. The percentage of impervious surface area was a significant negative predictor of alert distance and flight initiation distance, but it did not significantly influence buffer distance. The number of rubbish bins per unit area was a significant negative predictor of alert distance, flight initiation distance and buffer distance, whereas the availability of nut trees did not influence any of the escape variables. These results indicate that urban crows responded to humans differently on a fine spatial scale based on human population density and human-modified habitat features, including anthropogenic food availability, indicating that the heterogeneity of urban habitats should be accounted for in studies examining the behavioural responses of animals to urbanization.