Habitat Effects on Movement Are Mediated by Behavioural State in Juvenile White Storks

Understanding how environmental heterogeneity shapes animal movement is a central goal of movement ecology, yet movement metrics derived from GPS data often integrate multiple behavioural states, complicating ecological interpretation. We analysed 30,323 GPS observations from six juvenile white storks (Ciconia ciconia) to disentangle the effects of habitat and behavioural state on movement speed and altitude above ground level. Behaviour was classified into resting, local movement, and flight based on speed thresholds and incorporated into linear mixed-effects models alongside habitat. Behavioural state was the dominant determinant of movement metrics. Relative to resting, flight increased speed by approximately 43 km h−1 and altitude above ground level by approximately 566 m, whereas habitat effects were significant but substantially smaller. Differences in movement metrics among habitats were largely explained by variation in the distribution of behavioural states, with cropland dominated by resting behaviour and water associated primarily with flight. Sensitivity analyses based on alternative behavioural thresholds, leave-one-individual-out models, flight-only analyses, and alternative treatments of altitude above ground level produced consistent results. These findings demonstrate that habitat-associated variation in movement metrics is primarily mediated by behavioural state rather than representing a direct consequence of habitat alone. Our results highlight the importance of explicitly accounting for behavioural heterogeneity when linking movement to environmental conditions and provide a refined interpretation of the energy landscape framework.