1-0-1-2-1-2-1-2-1-2-1-2 Usually a chorus is initiated by one duet and is quickly picked up by other individuals also calling in duets. A numerical representation of a chorus of eight frogs would approximate the following organization: 1-0-1-2-1-2-1-2-1-2-1-2-1-2 3-0-3-4-3-4-3-4-3-4-3-4-3 5-6-5-6-5-6-5-6-5-6-5-6 7-8-7-8-7-8-7-8-7-8-7-8 After the first one or two duets are initiated, the second individuals in the following duets usually call immediately after their respective partners have given the first notes. The other noteworthy aspect about the organization is that the entire chorus usually stops abruptly. Normally the first duet stops calling shortly before the others, but this is not invariable. Often one duet or one individual will emit several notes after the rest of the frogs have become silent. An interval of several minutes sometimes elapses before the chorus begins again. Successive choruses apparently are initiated by the same duet. Responses can be initiated artificially by imitating the call, and sometimes any loud noise will start a chorus. Similar duets have been observed in _S. phaeota_. In this species the intervals are often much longer than the notes, and if two males are calling in close proximity, their calls can be mistaken for those of one individual. _Smilisca phaeota_ does not congregate in large numbers; usually only two males call from one restricted site. _Smilisca sila_ has a call consisting of a primary note followed by one or more secondary notes. Males often call in duets, but not necessarily so. In a duet, the first male usually utters only primary notes until the second individual responds; then each individual produces a rapid series of secondary notes. _Smilisca puma_ also produces primary and secondary notes. Although individuals sometimes call alone, duets, trios, or quartets were more common. The chorus is initiated by one individual uttering primary notes until joined by the second, third, and fourth frogs. In one quartet in a marsh 7.5 kilometers west of Puerto Viejo, Costa Rica, on February 19, 1965, the same individual initiated four consecutive choruses. Each time the second member of the chorus was the same; the third and fourth frogs joined the chorus nearly simultaneously. Individuals of _S. sordida_ are usually irregularly situated along a stream. No duets or other combinations of individuals are apparent in the chorus structure, but once an individual calls, a frog nearby calls almost immediately; then a frog near the second individual calls, and so on. The resulting series of calls gives the impression that the sound is moving along the stream as successive individuals join the chorus and the first callers become quiet. It is not known if the same individual initiates successive choruses or if the order of calling is the same in subsequent choruses.