Exploring the exploration: implications of leaving or remaining at the natal site during the early stages of independence in a partially migratory bird

Despite being an important fraction of any animal population, juveniles are a severely understudied group. Juveniles often need to learn an array of skills that allow them to survive independently and do so while undertaking decisions that may impact their fitness, recruitment and survival, having therefore relevant demographic implications. In partially migratory bird populations, some of the juveniles may remain all year near the natal area while others leave to spend one or more non‐breeding seasons elsewhere. The implications of remaining or leaving the natal area are likely to differ markedly. In this study we tracked 51 juvenile Eurasian Spoonbill Platalea leucorodia , of which 29 were classified as stayers or leavers (remaining at or abandoning the natal wetland area, respectively). All were equipped with GPS/GSM with 3‐axial accelerometer tags, which were used to classify behavioural and movement traits and tracked up to the end of their first year of life. When all juvenile Spoonbills were still in the vicinity of the natal wetland, the only difference found between them was that the amount of daily preening was higher for leavers. However, after displacement from the natal wetland, leavers invested more time and energy in foraging, while roosting less, decreased their amount of daily preening to values similar to stayers and used fewer habitat types. Leavers increased their use of anthropogenic habitats, although this did not differ from stayers . These differences in behaviour and movement traits appear to be driven by leavers being in new and unfamiliar areas, as there was no evidence suggesting that they may be caused by the energetic costs of the displacement. Longer displacements were associated with higher levels of behavioural change and, after some time (up to 1 month) in the new area, movement and behavioural traits did not level off. Remaining in the natal area appears beneficial, which may explain the apparent increase in the number of Spoonbills remaining in the Iberia Peninsula during the non‐breeding season. As technology is improving and becoming more accessible, further studies on the implications and carry‐over effects of these different patterns for the population would be highly beneficial, in order to further our understanding of population dynamics.