Foraging trade-offs and predator inspection in an Ostariophysan fish: Switching from chemical to visual cues

Under laboratory conditions, we investigated the presence of a foraging trade-off in the chemical predator inspection behaviour of finescale dace (Chrosomus neogaeus). Dace were fed ad libitum, or food deprived for 24 or 48 hours and allowed to inspect a live yellow perch (Perca flavescens) in the presence of the chemical cues of a perch fed dace (with alarm pheromone) or swordtails (Xiphophorus helleri; without alarm pheromones). Dace exposed to the 'odour of a perch fed swordtails exhibited no evidence of a trade-off in either antipredator behaviour or predator inspection behaviour. When fed ad libitum and exposed to the odour of a perch fed dace, individuals exhibited significantly greater anti-predator behaviour (increased shoaling, decreased area use and greater frequency of dashing and freezing behaviour) when compared to the swordtail diet control. Predator inspection behaviour was also significantly affected (increased latency to inspect and minimum distance approached towards the predator and fewer inspectors per visit). However, when food deprived for 24 or 48 hours, dace exhibited no differences in either anti-predator or predator inspection behaviour when exposed to the odour of perch fed dace versus perch fed swordtails. These data demonstrate that predator inspection behaviour based on the chemical cues of a potential predator is subject to foraging trade-offs and that individual prey may reduce their overall risk of predation by increasing the use of visual cues.