Symphalangus syndactylus

Short phrases of booms (during inflation of throat sac), simple barks (each preceded by short boom), and ululating screams. Short phrases are produced by either sex, but ululating screams are optional in females. Female great call with two acceleration-type climaxes, of moderate speed; second acceleration of shorter duration. Great call beginning with longer barks than those of short phrases, each bark preceded by short boom. Male produces booms during initial stages of great call, and a different scream at each climax: a special bitonal scream at the first climax, and a ululating scream at the second climax. After second climax, male and female utter a series of rapid barks and booms (locomotion call). After a few seconds of silence and a few booms, male produces a ululating scream as final coda. Duet song bouts.

a. male short phrases (Howletts Zoo, United Kingdom, 16 Oct. 1988).
b. great call sequnce consisting of female great call with overlapping male contributions (Metro Zoo, Miami, U.S.A., 31 July 1988).

Symphalangus syndactylus sound examples:

	Duet song, adult pair "Suma" and "Siam", Berlin Zoo, Germany, 29 June 1988. The twin offspring (1 year and 2 months old) of this pair do not vocalize much during this song bout.
	Duet song, adult pair "Festus" and "Olga", Metro Zoo, Miami, U.S.A., 31 July 1988. The infant offspring (about 9 months old) of this pair does not contribute to this song bout.
	Solo song, young adult solitary male "Xhari", Howletts Zoo, U.K., 16 Oct. 1988. A solitary male H. moloch ("Omar") also sings during this song bout.
	Solo song, adult solitary female "Gaspa", Zürich Zoo, Switzerland, 31 July 1981.