High and long-term repeatability of foot use preference in Japanese tits

Summary

Behavioural laterality, reflecting the asymmetry of brain structure and/or function, may influence an individual's fitness and has received increasing research efforts in recent years. The repeatability of the lateralized behaviour is a precondition of its correlation with fitness traits. Currently, studies on the repeatability of behavioural lateralization are mainly focused on captive animals, with knowledge about wild populations remaining scarce. We examined the repeatability of the preference of foot use (i.e. footedness) for grasping food against a perch in wild-caught Japanese tits, Parus minor, by testing a group of captive-raised birds within 16 days and testing the birds living in the wild, with a recapture interval ranging from 0 days to 1169 days. We found that an individual's sex and test interval did not affect its footedness score. High repeatability of footedness was found for both the captive group and the wild-recapture group. Across different recapture intervals of the wild-recapture group (0−60 days, 61−120 days, 121−365 days, >1 year), repeatability varied between 0.765 and 0.989, suggesting consistent foot use preference across seasons. Compared to the lateralized behaviours in most other species, footedness in wild Japanese tits showed a higher level of repeatability. We suggest that the birds in the family Paridae could be ideal systems for understanding the evolution of behavioural/cerebral lateralization for their potential to explore the interplay between lateralization and other fitness-related behaviours in the wild.