Short phrases consisting of simple hoots and more complex hoots, among which longer hoots with one or two frequency inflections ("wa-oo", "wa-oo-wa") are particularly prominent for this species. Short phrases uttered by males and females. Only one of the males regularly produced bi-phasic hoots (softer than those of H. agilis) and short trills. Female great call consisting of a series of accelerated notes; climax not marked by particular frequency modulation of notes, but by moderately accelerated rhythm of notes becoming slower again at the end of the great call. Male does not produce coda. Male solo song bouts and female solo song bouts.
a. male short phrases (Munich Zoo, Germany, 16 July 1987; and Howletts Zoo, United Kingdom, 17 Oct. 1988)
b. great call sequnce consisting of female great call only (Munich Zoo, Germany, 16 July 1987)
|Solo song, adult mated male "Paul", 16 July 1987, Munich Zoo, Germany.|
|Solo song, adult solitary male "Omar", 16 Oct. 1988, Howletts Zoo, U.K.|
|Solo song, adult mated female "Ludmilla", 16 July 1987, Munich Zoo, Germany.|
|Solo song, female, 30 Sept. 1998, Dieng Plateau, Java, Indonesia.|
|Solo scream bout, female, 26 Sept. 1999, Dieng Plateau,
Java, Indonesia (rec. Vincent Nijman).
A second female is calling in the background. Presumably a border conflict call bout.
|Communal call bout of family group, consisting of adult pair "Ivanowitch" and "Paula" and their juvenile son (2 year old), Berlin Zoo, Germany, 30 June 1988.|
|Female great call from later in the same call bout as above, adult mated female "Paula", Berlin Zoo, Germany, 30 June 1988.|
|Disturbance hoots, mated male, 1 Oct. 1998, Dieng Plateau,
The male hoots at the observer. Hoots like these may occasionally develop into male solo song bouts. This did not happen on this particular occasion.
|Duet song, adult male H. lar and adult female
H. moloch, 30 April 1979, Knie's Kinderzoo, Rapperswil, Switzerland (rec.
Interestingly, duetting between these two species is possible, although H. moloch pairs are not known to produce duets.