Overcoming Innate Lateralization Improves Avian Flight Performance

Behavioural lateralization -behavioural side-bias or handedness- enhances neurological processing efficiency and task execution but creates a dilemma for behaviours requiring symmetry. Flight demands symmetric execution, particularly when optimising energy extraction from atmospheric updrafts during soaring. Using high-resolution biologging of 31 juvenile European honey buzzards from fledging through the completion of their first intercontinental migration leg, we show that strong lateralised circling was prevalent immediately after fledging (74%). This proportion declined to parity by migration onset, indicating developmental adjustment with increasing experience. During migration, side‑biased circling was linked to wider turns taken, reduced altitude gain, and daily travel distances shortened by 13%. These findings reveal a direct trade-off between the neurological efficiency of lateralization and the aerodynamic requirements of efficient soaring. More broadly, they demonstrate that behavioural asymmetries can constrain, rather than always enhance, performance. Our results challenge the notion that lateralization is universally adaptive and highlight how experience and ontogeny modulate the balance between perceived task difficulty, neural specialization, and ecological performance.