Against the backdrop of rapid urbanization that continuously aff ects the structure and functions of blue-green spaces, elucidating the diff erential response mechanisms of avian diversity is a key topic in urban ecological research. Focusing on Changning District, Shanghai (a typical high-density urban area), this study established 300 m buff er zones around 45 bird observation sites, constructed an avian diversity index system (including species richness, Shannon-Wiener, Simpson, and Pielou evenness indices), and extracted 8 blue-green space indicators from four dimensions. Samples were divided into high and low-intensity groups based on development intensity, and multiple linear regression models were fi tted using full-region samples to compare response diff erences. Results indicated notable diff erences in the impact mechanism of blue-green spaces relative to development intensity: in areas characterized by low development intensity, species richness was primarily infl uenced by green space coverage, whereas diversity was associated with landscape evenness; in regions with high development intensity, the explanatory effi cacy of conventional blue-green space indicators diminished considerably. Meanwhile, bird species richness was more sensitive to green space characteristics, whereas diversity indices were more regulated by overall landscape patterns. From the perspective of the development intensity gradient, this study reveals the dynamic changes in the ecological function of bluegreen spaces in maintaining avian diversity amid urbanization, providing a scientifi c basis for diff erentiated ecological regulation in high-density cities.