Individual variation in avian avoidance behaviours in response to repeated, simulated vehicle approach

Birds exhibit variation in alert and flight behaviours in response to vehicles within and between species, but it is unclear how properties inherent to individuals influence variation in avoidance responses over time. We examined individual variation in avoidance behaviours of Brown-headed Cowbirds (Molothrus ater (Boddaert, 1783)) in response to repeated presentation of a simulated vehicle approach in a video playback scenario. We modeled temporal alert and flight behaviours to determine whether overall behavioural variation resulted primarily from variation within individuals (i.e., intraindividual variation) or between individuals (i.e., interindividual variation). We examined reaction norms (individual × treatment day) and whether birds showed plasticity in responses via habituation or sensitization. Repeatability in the response metrics for individuals was low (∼0.22 for alert and flight), indicating that model variation was due primarily to within-individual variation rather than between-individual ...