Figure 1. Courtship drums and recording setup.

Oscillograms of courtship drums made by (a) the painted goby (Pomatoschistus pictus) and (b) the sand goby (P. minutus). The long line indicates sound duration whereas the short line depicts the interval between two consecutive pulses. (c) Setup used for the sand goby recordings illustrating the outer compartments occupied by territorial males and a female in the central compartment and the position of the two hydrophones. Trials began by removing one partition (illustrated by the arrow) which allowed interaction between one male and a female.