Sounds and Vocal Behavior

Male Bare-throated Bellbirds appear to prefer the tallest trees in the canopy from which to call, which they typically do from exposed, uppermost branches during the breeding season, and possibly year-round (Bodrati et al. 2010). The song, which is considered one of the more strongest voices produced by a bird in South America, is composed of two elements: a scream which resembles the sound of a hammer slamming into a blacksmith's anvil, which is repeated at ca 5 second intervals; and followed by a sound that resembles a file in friction against iron (Sick 1997). These two elements each can be given separately, or in a series of one, then the other. The loud anvil strike or bonk call is given with the bill wide open, during which the male may swing his head and body, as if trying to direct the call in a certain direction. A male may initiate a sequence with the loudest bonk, this call repeated more rapidly and weakly in the end: BONK…...….. bonk.…... bonk…... bonk….. bonk… bonk... bonk... bonk... The number of bonks can vary greatly between calling bouts given by a male, from two to several dozen. In Paraná State, Brazil, Leuchtenberger and Roper (2003a) documented more than 50 repetitions of the bonk call within a call sequence.

Subadult males also call but without the tonality of adult males, with their calls sounding hoarse and croaky. It likely takes two or three or years to acquire the quality of the male adult’s call (Sick 1997). Leuchtenberger and Roper (2003a) evaluated the variation in the composition of calls within and among males and suggested that such variation is something the female can use to measure male quality. There is no evidence that females vocalize regularly. Also see descriptions of the vocalizations of Bare-throated Bellbird by Snow (1973), Belton (1985), Sick (1997), and Kirwan and Green (2011).

As well as calling, males perform display-jumps in which they quickly flutter the wings, then jump to a nearby perch, repeating this several times. One male in Rio Grande do Sul State, Brazil jumped 20 times between two branches that were ca 50 cm apart in one bout that lasted approximately two minutes, in early October, 2017, during which it called intermittently. Males will also posture towards other males in an apparent dispute over territory or perch. In December, one adult male was seen in Rio Grande do Sul, Brazil, posturing to a subadult male in the same tree by raising itself on its extended legs (similar to the display described by Kirwan and Green 2011) before chasing it off.

Additional audio recordings of Bare-throated Bellbird vocalizations can be heard at Macaulay Library and at xeno-canto.

The function of the indentation on the tip of the eighth primary feather is unknown. It may produce a mechanical noise during flight, since males in flight can be heard flying if close enough to the observer (A. Jahn, personal observation).