In this project we will assess a number of methods that may be useful to determine individual personality differences. These include (chronologically) behavioural observations in the field, behaviour in the hand, physiology in the hand, and behaviour in a test arena. With these data we hope to establish which methods show the best internal consistency, and which are the best choice in terms of cost and effectiveness. These data are collected in the context of the invasive species problem. Several invasive passerine birds occur commonly in the Donana area, but seem more scarce within the core reserve. This may be because escaped and released invasives have been changed due to selection on personalities while in captivity, and this may prevent them from coping successfully with natural predators. This question will be addressed by comparing the personalities of invasives from outside and inside the reserve.