Behavioural syndromes and trappability in free-living collared flycatchers, Ficedula albicollis

The concept of behavioural syndromes hypothesizes that consistent behaviours across various situations mediate important life history trade-offs, and predicts correlations among behavioural traits. We studied the consistency of behavioural responses across three ecological situations (exploration of an environment altered with a novel object, aggression towards conspecifics, risk taking) in male collared flycatchers. We developed behavioural tests that could be applied in the birds' natural habitat, thus not requiring the capture of animals. Across individuals, we found positive covariation between exploration, aggression and risk taking, but the magnitude of these relationships varied. Variation in behaviour was also related to capture probability. Exploratory and risk-taking individuals were more likely to enter a trap than individuals with averse characteristics. Moreover, with the trapped birds, there was an association between the time needed for successful capture and exploration, and we found stronger correlations between behaviours in comparison with effects calculated from the whole sample of individuals. These patterns were independent of territory quality, male age, condition and breeding experience. Consequently, behavioural responses to different ecosocial challenges are determined by individual-specific characteristics that are manifested in correlative behaviours. Hence, behavioural types may be potential subjects for reproductive and life history adaptations. Our results have important implications for field studies of animals, because they suggest that capturing protocols may not randomly sample the observed population.