A male’s playback signal turns female Marcusenius pongolensis receivers on or off depending on his behavioural state

Abstract

The electric organ discharges (EODs) of male southern bulldog fish, Marcusenius pongolensis, are of longer pulse duration than those of females, and grow with body size. In a playback experiment, male EODs of longer pulse duration were more attractive to females in terms of association time and other behavioural variables. Here, we show that the greater attraction of long male EODs to females was only revealed when combined with ‘acceptable’ information on his behavioural state (the combination was manipulated experimentally). Females were attracted to long EODs had the male (apparently) been in a nocturnally-active but non-aggressive behavioural state, but the preference vanished when in a diurnally ‘resting’ or nocturnal aggression (agonistic) state. Information on male behavioural state was conveyed to females by one of four types of inter-discharge interval (IDI) pattern that were used to drive the presentation of EODs.