Predator personality and prey detection: inter-individual variation in responses to cryptic and conspicuous prey

Limited attention constrains predators from engaging in cognitively demanding tasks such as searching for cryptic prey at the same time as remaining vigilant towards threats. Since finite attention can result in negative correlations between foraging and vigilance, the tendency of individual predators to focus attention on searching for cryptic prey may be correlated with other behavioural traits which reflect risk-reward trade-offs, such as consistent inter-individual variation in boldness (a personality trait describing risk-taking, defined in this study as the time taken to leave a refuge). We investigated the importance of personality in prey detection by comparing inter-individual variation in the response of three-spined sticklebacks (Gasterosteus aculeatus) to conspicuous and cryptic prey. Fish were slower to attack cryptic prey than conspicuous prey, consistent with cryptic prey being harder to detect. Despite the greater challenge involved in detecting cryptic prey, inter-individual variation in the time taken to detect prey was similar in the cryptic and conspicuous prey treatments, and was uncorrelated with boldness, which was repeatable between individuals. We also observed a positive association between the rate of attack on conspicuous prey and whether individual fish attacked cryptic prey in other trials. Our findings suggest that boldness is not related to prey detection or attention in this context. Instead, consistent differences in motivation once exploration has begun between individual predators may explain inter-individual variation in the time taken to attack both prey cryptic and conspicuous prey.