Individual behavior responds dynamically to environmental conditions, yet many ecological models rely on population averages that overlook structured behavioral variation. We develop a behaviorally structured modeling framework that treats behavior as a continuous trait and links individual-level responses to population-level ecological dynamics. The model integrates population dynamics with behavioral distributions, capturing feedback between environmental conditions and individual responses. Using analytical and numerical methods, we show that behavioral heterogeneity fundamentally reshapes system dynamics, including stability, transient responses, and the emergence of critical transitions. Our results reveal that changes in behavioral distributions can modify persistence and resilience, and can alter the onset and progression of regime shifts in ecological systems. These dynamics arise from feedback between environmental variation and behavior, which is absent in traditional mean-based approaches. This work establishes behavior as a central mechanism in ecological dynamics and provides a mathematically grounded framework for improving ecological prediction under environmental change.

Keywords: Ecological forecasting; Behavioral plasticity; Trait-structured models; Population dynamics; Regime shifts