Hylobates pileatus

Short phrases of bi-phasic hoots ("oo-wa") of hiccup-like quality, simple hoots and short trills. Bi-phasic hoots consist of notes alternatingly produced during exhalation and inhalation, as in H. agilis. Short series of inhalation hoots only or exhalation hoots only also occur. Short phrases are produced by either sex, but more frequently and usually louder by males. Female great call with an acceleration-type climax, like H. muelleri, with similar, fast bubbling note production, and without becoming slower at the end of the great call. Great call usually longer than in H. muelleri, and first great call notes usually more drawn out (the muelleri great call shown in the sonageramm above is unusually long). Male produces coda, beginning halfway through the great call. Male solo song bouts and duet song bouts.

a. male short phrases (Zürich Zoo, Switzerland, 5 May 1988; and Berlin Zoo, 29 June 1988)
b. great call sequnce consisting of female great call with overlapping male contribution (Zürich Zoo, Switzerland, 5 May 1988)