In general, the voice of C. sericocuadatus has been described as a trisyllabic “doh-diew-lewt” with a timbre of the Common Pauraque (Nyctidromus albicollis) and sung in extensive sequences of 3 minutes or more (Sick 1993) with noted differences between subspecies.
C. s. sericocaudatus: (1) has a short tonal gliss connecting the two major pitch peaks “ree-o-ree;” very similar to C. badius (Hardy and Straneck 1989) and (2) has an almost mournful, undulating “doh wheo eeo” which is repeated for several minutes with a brief pause between notes (Cleere 1998).
C. s. mengeli: (1) has phrases composed of a continuous tonal figures (a whistle-like sound) that is slowly frequency and amplitude modulated; it is further similar in having an overall ascending pitch that rises and falls three times in its course, producing three frequency peaks and valleys, each successively higher than its predecessor (Hardy 1985); (2) has a noticeably higher-pitched sound with a longer tonal gliss connecting the two major pitch peaks of its utterance (Hardy and Straneck 1991) and (3) is more melodious, is drawn-out, and has a higher-pitched “doh wheeo weeeo” (Cleere 1998).
Robert Straneck had tape recorded, and subsequently collected, an individual in northern Argentina in November 1986. He recorded two different vocalizations which he refers to as Song 1 and Song 2 (Hardy et. al. 1997). After examining these vocalizations, Song 2 (Fig. 1 C) is most likely a communication call between the adult and nestling. These calls are very similar to recordings made between adult Ocellated Poorwills (Nyctiphrynus occellatus) and their young when they are separated and trying to locate one another (Wilkinson, unpubl. data).
During the breeding season, both males and females of the same pair vocalize with the same sound (see A in sonogram) and I refer to it as a “call” rather than “song” (see Behavior). Birds call from or near the nest, on low perches up to 5 m high or while in flight low to the ground during the crepuscular hours. Individuals at CCBS typically called only once or a few times during dusk and dawn, although several extensive sequences were heard for up to 45 minutes. Birds have not been recorded calling outside of the breeding season at CCBS but in Misiones, Argentina, birds may sing all year (Cleere 1998).