Alternative foraging tactics and risk taking in brook charr (Salvelinus fontinalis)

Abstract

Recently emerged brook charr (Salvelinus fontinalis) foraging in still-water pools along the sides of streams tend to be sedentary, feeding from the lower portion of the water column (sitting and waiting), or active, feeding from the upper portion of the water column (active search). Individuals exhibiting intermediate behavior are observed less frequently. We assessed the perceptual, energetic, and locomotor bases of the individual differences in foraging tactics by testing whether an individual's activity while searching for prey in the field was linked to its willingness to take risks, resting metabolic rate (RMR), and swimming capacity. Proportion of time an individual spent moving during prey search was quantified in the field, the individual was captured, and willingness to take risks (field), resting oxygen consumption (lab), and locomotor ability (lab) were measured. Individuals that spent a lesser proportion of time moving in the field took longer to exit from a dark tube into an unfamiliar field environment, and delayed their exit times more in response to a novel object, than did individuals that spent a greater proportion of time moving in the field. Proportion of time spent moving in the field was unrelated to resting oxygen consumption and swimming capacity measured in the laboratory. Dispositions in foraging behavior and risk taking early in life could influence encounter rates with novel prey and habitats, which are important steps in the initial stages of resource polymorphisms.