Perceptual worlds and divergent foraging tactics in brook charr

Recently emerged brook charr (Salvelinus fontinalis ) exhibit conspicuous individual differences in their activity and space use while foraging. I tested whether these behavioural differences reflected differences in how risky individuals perceive their environment. I first tested alternative hypotheses regarding the links between perceptual, energetic, and locomotor mechanisms and foraging behaviour to demonstrate that differences in the foraging tactics exhibited in the field by the charr reflect individual differences in willingness to take risks in novel situations. I then combined behavioural and endocrine approaches to demonstrate that differences in foraging tactics exhibited by young brook charr reflect individual differences in basal, whole-body cortisol concentrations, a hormone linked to personality differences in domestic rainbow trout. My findings provide initial, novel evidence that individual differences in perception may be involved during early stages in phenotypic diversification as seen in resource polymorphisms observed in fishes inhabiting northern lakes.