Oddity and the 'confusion effect' in predation

We report on two sets of experiments designed to clarify the roles of sensory 'confusion' and prey 'oddity' as they interact to influence the hunting success of a pursuit predator, the largemouth bass (Micropterus salmoides), on silvery minnows (Hybognathus nuchalis). Bass quickly captured solitary minnows, but performed many unsuccessful attacks and took much longer to make a capture as prey school size was increased. At school sizes of eight and above, bass were effectively stymied, demonstrating the 'confusion effect'. The inclusion of one or two 'odd' (blue-dyed) minnows in a school of eight greatly increased the ability of bass to capture both normal and odd prey, but this effect of oddity disappeared at a school size of 15. The implications of these results for understanding the adaptive basis of mixed species flocks, herds and schools is discussed. © 1986.

Duke Scholars

Author John W. Terborgh Environmental Sciences and Policy