Resource phenology and transient dynamics shape urban avian guild stability: A modeling framework for urban green planning

Urban ecosystems exhibit pronounced temporal and spatial variability, yet the mechanisms by which resource pulses and habitat heterogeneity shape avian community stability remain poorly understood. Using generalized linear mixed models and sensitivity analyses, we examined how fruit and nectar availability influence the transient dynamics of frugivore and nectarivore guilds across urban sites in northern Taiwan. Resource pulses during peak fruiting periods significantly enhanced frugivore stability, while nectarivores remained unstable due to spatiotemporally ephemeral floral resources. Spatial heterogeneity further modulated these effects: fragmented habitats limited fruit availability, thereby necessitating a dietary shift toward animal prey, which was associated with amplified community volatility. Our framework integrates diet composition, phenological timing, and “structural stability” to model non-equilibrium dynamics under urban change. These findings underscore the need for dynamic biodiversity models that account for transient responses to resource and habitat fluctuations, informing adaptive urban conservation strategies. The study framework illustrates how seasonal resource phenology drives avian guild stability. (Left) Seasonal fluctuations create resource gaps (e.g., Winter) in urban fragments. (Middle) Modeling reveals that resource scarcity increases the Transient Dynamics Index (TDI), resulting in volatile communities, whereas abundance promotes stability. (Right) To mitigate this instability, we propose a phenology-driven design using staggered native plantings (e.g., Prunus campanulata , Gordonia axillaris ) to bridge temporal gaps and enhance resilience. • Summer fruit pulses act as “stabilizing windows” that dampen system reactivity. • Winter “phenological gaps” drive high volatility in urban nectarivore guilds. • Forced dietary switching in fragmented sites indicates potential “ecological traps.” • High-density fruit patches trigger aggregative numerical responses, boosting resilience. • Proposes “phenology-driven design” to bridge resource gaps and enhance stability.