Aerophile surnichrasti August 15 5 miles east of Tehuantepec, Oaxaca, Mexico ie, the male may finish first, the female or both together. Generally, the male appears (and sounds) it is the last to finish. The vocalizations of the members of 3 different pairs were dimorphic: the male (assumed) utters a distinctly different phased "song" consisting of high & lower-pitched notes, the female seems to utter a more uniform "song" consisting of double-noted phrases of fairly high pitch and only a slight change in emphasis. Thus the "songs" might be rendered. The exact synchrony is not easily determined but appears to be fairly uniform, ie, the "dueting" sounds the same from time to time. FF's rarely give their "song" while the male is not also singing, but it was heard ca 6 times.