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Nomascus gabriellae |
Fully developed male vocalisations similar to N. concolor, but booms usually missing, and series of short staccato notes ("aa") uttered very softly. The first note of the multi-modulated figure beginning with a long section of descending frequency; extremely rapid changes of frequency modulation (trill) occur on second note only. Females produce great calls only. Great call similar to N. concolor, usually about 5-13 notes, but each beginning with ascending frequency. Notes begin at higher frequency than both N. concolor and N. leucogenys. Male produces multi-modulated phrase as coda. Duet song bouts.
a. male short phrases (La Flèche Zoo, France, 29 May 1988)
b. great call sequnce consisting of female great call with male contribution (Mulhouse Zoo, France, 13 Sept. 1988)