Urban bird diversity and ecosystem services are shaped by fine-scale habitat features

Biodiversity and ecosystem services are known to respond to large-scale urban planning, but the ecological role of fine-scale, designable habitat features remains poorly quantified We analysed bird communities across six Italian cities in relation to habitat and human-designed features measured at a 100-m scale, quantifying taxonomic diversity and trait-based proxies of cultural (e.g. aesthetic appeal) and regulating (e.g. seed dispersal, pest control) ecosystem services. Grass and water were key predictors: grass-rich areas supported more diverse bird communities, while aquatic features enhanced both diversity and regulating services. Impervious surfaces reduced diversity and cultural values, whereas intermediate vegetation height maximized diversity, highlighting the value of structural heterogeneity. Scenario modelling showed that expanding green areas improved avian diversity far more than increasing tree height, while green-area loss caused severe declines. Our findings emphasize that integrating blue-green infrastructures and habitat complexity into urban design is essential to foster biodiversity and ecosystem services, supporting the EU Biodiversity Strategy 2030 and UN Sustainable Development Goals.