Predator inspection behaviour in minnow shoals:differences between populations and individuals

When minnows (Phoxinus phoxinus) detect a stalking pike (Esox lucius) one of their first responses is to perform 'inspection behaviour' during which individuals or small groups approach the predator. This paper compares the inspection behaviour of two contrasting groups of minnows: Dorset minnows which have been heavily predated by pike for many thousands of years and Gwynedd minnows which have spent an equivalent period of time in a pike free environment. Minnows sympatric with pike inspected a realistic model pike more frequently and in larger shoals. Although they commenced inspection earlier they were more timid and kept a greater distance between themselves and the predator. After an inspection they were less likely to recommence foraging than minnows from the Gwynedd population. Individual differences in inspection found within the two populations suggest that selfish behaviour was present.