Biologging and mechanistic niche modelling reveal thermal dependence of individual lizard movement patterns

Assessing how variation in thermal physiology and body size influences locomotor performance under ecologically relevant conditions is essential to predicting population vulnerability to climate change. We combined fine-scale animal biologging and individual-level mechanistic niche modelling to unravel animal-environment interactions in ocellated lizards (Timon lepidus) kept in semi-natural mesocosms. We classified mobility states from accelerometer data to describe individual movement patterns. We produced continuous body temperature predictions through individual mechanistic models and used thermal performance curves (TPCs) to assess how body temperature influences locomotor performance. We further tested for evolutionary trade-offs and simulated mobility windows under warming scenarios. Our results provided high-resolution estimates of body temperature across mobility states, revealing how variation in thermal physiology is associated with movement. We found that individuals occupied different positions along a 'specialist-generalist' continuum of thermal strategies: some achieved higher locomotor performance but within narrower thermal ranges, while others displayed broader mobility windows but lower locomotor maxima. On the other hand, body size did not affect movement patterns under current climatic conditions, but warming simulations indicated that larger individuals may experience disproportionately greater increases in mobility under extreme warming. These findings demonstrate that even subtle variations in thermal physiology and body size can translate into differences in locomotor performance and mobility. By integrating physiological, behavioural and microclimatic data, our framework provides a powerful approach for predicting how climate change may reshape the spatial and temporal niches of ectotherms.