Ducks in a row: the incidence of aggression and vigilance behaviour in Australian wood ducks (<i>Chenonetta jubata</i>) along an urbanisation gradient

Urbanisation reshapes landscapes and profoundly impacts biodiversity. While some species decline or disappear in urban environments, others thrive. One of the most conspicuous adaptors to urbanisation are birds, many of which exhibit behavioural plasticity. Understanding the adaptations of common species is critical for informing conservation efforts and designing urban landscapes that support native biodiversity. This study investigates the behavioural plasticity of the Australian wood duck (<i>Chenonetta jubata</i>), a species that has successfully adapted to open green spaces in Melbourne, Australia. We examined the frequency of intraspecific aggression (attack and warn) and vigilance (scan) behaviours across a gradient of human population density and considered sex, season and group size. Male ducks exhibited more aggression and vigilance than females, particularly in autumn and in larger groups. However, these relationships were mediated by the level of human activity: attack behaviour was more frequent in male ducks and in autumn at lower density sites, but in both cases this difference lessened with increasing human population density. There was also an increased occurrence of attack and warn behaviours with human population density in larger groups. Scan behaviour increased with human population density across all variables, especially in spring and in smaller groups. These findings indicate that Australian wood ducks modify their behaviour in response to urbanisation. Species lacking this behavioural plasticity, particularly those with niche habitat requirements, may struggle to persist in cities unless considered in the design and management of open green spaces.