Heads up: juvenile convict cichlids switch to threat-sensitive foraging tactics based on chemosensory information

Abstract

The ability to accurately assess local predation risk is crucial, as it allows prey individuals to maximize trade-offs between predator avoidance and foraging behaviour. Here, we test the hypothesis that juvenile convict cichlids, Archocentrus nigrofasciatus, rely on ambient chemosensory information to make threat-sensitive foraging decisions. In experiment 1, juvenile cichlids were exposed to conspecific chemical alarm cues above or below the threshold required to elicit an overt antipredator response and were allowed to forage on a choice of horizontal (on the substrate) or vertical (perpendicular to the substrate) food patches. Although cichlids exposed to a subthreshold alarm cue did not show an overt antipredator response, they significantly increased their use of the vertical food patch (head-up foraging posture). Cichlids exposed to a suprathreshold alarm cue significantly reduced foraging and aggressive behaviour and shifted to the head-up foraging position. In experiment 2, juvenile cichlids were exposed to the odour of an adult conspecific fed a vegetable diet, or one of two prey fish diets (juvenile cichlids or swordtails, Xiphophorus hellerii), or a distilled water control. Although we found no evidence of an overt antipredator response towards any of the stimuli, cichlids exposed to the odour of predators fed a prey fish diet significantly increased their use of the head-up foraging posture. Our results clearly show that juvenile cichlids are able to adjust their foraging patterns in a threat-sensitive fashion in response to ambient chemosensory information.