Individual plasticity drives boldness senescence in a territorial butterfly

Abstract Most behavioural traits show plastic responses to changes in internal or external conditions. Similarly, animal personality is not necessarily fixed during an individual’s lifetime, leading to age‐related changes. Both individual plasticity (i.e., within‐individual effect) and non‐random selective (dis)appearance of behavioural types (i.e., between‐individual effect) may contribute to age‐related changes observed at the population level. Here, we investigated how boldness changes with age in a woodland population of the Speckled wood butterfly (Pararge aegeria L.) using a capture–mark–recapture approach. We used wing wear as an index for age and we show that fresh individuals are bolder than worn individuals. Using the subsample of recaptured butterflies, we found that this pattern is most likely driven by individual plasticity. Our design also allowed us to explore some aspects of the species’ spatial ecology and how it relates to personality. We found no relationship between boldness and net displacement between successive captures, a finding which we discuss within a movement ecology framework