Urban green spaces significantly influence avian communities, with land cover area and heterogeneity negatively correlated. This trade-off does not affect overall bird richness but influences community composition. Urban avoiders thrive in large, heterogeneous green patches, while urban planners should consider landscape context alongside within-green-area heterogeneity. Green space design should limit configurational heterogeneity to conserve avian richness. The study, conducted across six European cities, found that land cover heterogeneity positively correlates with richness of urban avoiders, and larger green areas surrounded by diverse land covers support higher bird richness. Urban avoiders, which are most at risk in cities, benefit from large, heterogeneous green patches. To protect these species, green space managers and urban planners should prioritize maintaining large vegetated areas and land cover diversity within the urban matrix. The study highlights the importance of balancing land cover area and heterogeneity in urban green space design to conserve avian biodiversity.Urban green spaces significantly influence avian communities, with land cover area and heterogeneity negatively correlated. This trade-off does not affect overall bird richness but influences community composition. Urban avoiders thrive in large, heterogeneous green patches, while urban planners should consider landscape context alongside within-green-area heterogeneity. Green space design should limit configurational heterogeneity to conserve avian richness. The study, conducted across six European cities, found that land cover heterogeneity positively correlates with richness of urban avoiders, and larger green areas surrounded by diverse land covers support higher bird richness. Urban avoiders, which are most at risk in cities, benefit from large, heterogeneous green patches. To protect these species, green space managers and urban planners should prioritize maintaining large vegetated areas and land cover diversity within the urban matrix. The study highlights the importance of balancing land cover area and heterogeneity in urban green space design to conserve avian biodiversity.