Flight initiation distance changes across landscapes and habitats in a successful urban coloniser

Urbanisation is a major land use change that introduces novel sources of disturbance and risk into an ecosystem. Successful urban species modify their fear behaviour in response to the new conditions, as evolutionary mismatches between fear responses and environmental conditions are likely to have negative fitness consequences. Here we tested the effect of urbanisation on the fear response of a successful urban coloniser, the Australian Brush-turkey (Alectura lathami), using flight initiation distance (FID) as a measure of boldness. We predicted that Brush-turkeys in areas of natural vegetation would have longer FIDs than birds in more urbanised environments, and that males would have shorter FIDs than females. We recorded the FIDs of 80 Brush-turkeys across the Sydney region. We found that Brush-turkeys in natural vegetation and urban bushland reserves had longer FIDs than birds in urban streets and lawns. However, there was no difference in FID between sites in natural vegetation and urban bushland reserves. There was no difference in FID between male and female Brush-turkeys, between birds engaged in different behaviours, or between birds approached in the breeding and non-breeding seasons. Our results identified that Brush-turkeys displayed reduced fear behaviour in response to humans in more urban environments.