In an attempt to integrate behaviour, morphology and physiology in an evolutionary context, we (Møller et al.) conducted a phylogenetic comparative analysis using 63 species of European birds. Specifically, we sought for morphological (wing area, aspect ratio – determinants of flight capacity) and physiological (haematocrit – proxy of oxygen transport) underpinnings of the risk-taking behaviour expressed as flight initiation distance when approached by a predator (human observer). The manuscript was submitted to Journal of Evolutionary Biology and is now under major revision.