Male European and Japanese male quail have very stereotyped calls. This study examined which parameters best discriminated between individuals, and which between the two sub-species and a hybrid of the two (European father x Japanese mother). Recordings were made of several calls from individual Japanese, European and hybrid quail, from which sonograms were made and analyzed. We found that parameters describing the time structure of the call discriminated best between individuals. Time structure also showed the greatest differences between the two sub-species and the hybrid. Hybrid calls were extremely variable, individual hybrids often producing more than one call type, occasionally of both sub-species types. However, individuals could still be identified from the call parameters. In addition, we investigated responses of males to playbacks of calls from all three quail types. European and Japanese males responded most strongly, with calling, to the playbacks of the calls of their own sub-species, intermediately to playbacks of the hybrid and least to those of the other sub-species.