Common Environmental Responses of Bird Functional and Visual-Attractiveness Diversity in Urban Residential Areas

Urban residential areas are important habitats for birds and settings for residents’ daily contact with nature. Whether morphological functional-trait diversity and variation in species-level visual-attractiveness scores share environmental responses remains unclear. We surveyed 78 transects within 33 residential areas along the Min River in Fuzhou, China, over 12 months and integrated local vegetation, built-environment, and multi-scale landscape predictors. Grouped nested cross-validation, extreme gradient boosting (XGBoost), and out-of-fold (OOF) SHapley Additive exPlanations (SHAP) were used to compare predicted responses. Model performance was moderate for five metrics (OOF R2 = 0.250–0.404). (1) Total tree cover, mean tree height, and tree richness were the most consistent predictors of functional-trait and visual-attractiveness dispersion, while other effects were metric-specific. (2) Matched functional dispersion (FDis) and Rao’s quadratic entropy (Rao’s Q) metrics showed predicted responses that were predominantly concordant with those for tree-related variables, whereas local response divergence was concentrated in low-contribution understory variables. Most functional–visual associations and response-curve similarities did not consistently exceed null expectations from shared community composition. Model performance also declined under square-root and presence/absence weighting. (3) These findings support consideration of mature-tree retention, context-appropriate canopy structure, tree richness, and differentiated understory management, without treating higher-response intervals as causal targets. Concordance does not establish independent ecological synergy or measured aesthetic benefits.