Similar flight performance but sex-specific energetic strategies in homing pigeons

We quantified movement effort using Vectorial Dynamic Body Acceleration (VeDBA), a well-established index of energy expenditure. Overall, flight was associated with a marked increase in mitochondrial respiration linked to aerobic energy production, with increases ranging from 58.2% to 87.3% across traits, in both sexes. Flight performance did not differ between sexes: males and females showed similar flight speeds, flight durations, and social flight behavior (flying alone or in groups).

Nevertheless, females, which are smaller than males, showed higher VeDBA and higher post-flight mitochondrial aerobic metabolism than males, indicating sex differences in both mechanical and physiological responses. Independently of flight status, males exhibited higher mitochondrial coupling efficiency than females, although this difference was accounted for by body mass, indicating that a greater proportion of respiration was used for ATP production rather than being dissipated as heat in heavier individuals.

Together, these results show that similar flight performance can be associated with different energetic signatures and highlight sex as an important source of physiological variation in free-living animals.