How to measure animal personality and why does it matter? Integrating the psychological and biological approaches to animal personality

During the last few years individual differences in nonhuman animal (hereafter “animal”) behavior have been a subject of rapidly growing research interest (reviews in Réale et al. 2007; Sih and Bell 2008). This has met the much older research tradition of personality psychology, which includes human and, more recently, animal personality (Gosling 2001). Individual differences in behavior and their underlying psychology are now increasingly relevant research fields in several species of animals