Overcoming Innate Lateralization Improves Avian Flight Performance
Behavioural lateralization--side-bias or handedness--enhances neurological processing efficiency 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 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, 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. Our results challenge the notion that lateralization is universally adaptive and highlight how experience and ontogeny modulate the balance between task difficulty, neural specialization, and ecological performance.