Sound production during the spawning season in cavity-nesting darters of the subgenus Catonotus (Percidae : Etheostoma)

The cavity-nesting darters Etheostoma nigripinne, Etheostoma crossopterum, and their hybrid (E. nigripinne x E. crossopterum) were found to produce so unds associated with reproduction. Males produced sounds during aggressive encounters and courtship activities. All three taxa produced nonpulsed soun ds categorized as drums and shorter, usually pulsed, sounds categorized as knocks. In addition, E. nigripinne produced pulsed sounds referred to as pu rrs that differ from knocks in having a higher pulse number and rate. All s ound types were made under both aggressive and courtship contexts by males of all three taxa, The dominant frequency and duration of sounds differed b y sound type (drums, knocks, purrs) for all taxa. In addition, within the d rum sound type, the dominant frequency differed between contexts (aggressio n vs courtship) and among taxa. Although sound production has been document ed for numerous fish species, this is the first time sounds have been descr ibed for percids. The mechanism and role of sound production in darters has yet to be determined.