| Vocalization Usually
the singing is observed in the morning and
occasionally in the afternoon. About 2-3% of the
awakening time is spent in its territorial calls,
which usually forms nearly 90% of all
vocalizations.
Each
bout or sequence of a song is usually initiated
by the adult male. Each sequence lasts for 12-20
seconds. There are about 40-45 such sequences
over a period of 2-45 minutes.
The
various other sounds made are a deep throated
growl or a self exhilaration sound with the lips
pursed, both probably for communication between
and within the group.
Other
sounds are made by juveniles and infants during
play. The young ones produce a low-pitched
“cuo-cuo” voice during play and
whenever they are in difficulty or in trouble.
“eek” notes and solo singing are
observed for short durations.
Individuals
Hoolock vocalize in different forms according to
their age and situation. The adults sing and
produce loud and elaborated duets to advertise
their presence in a particular territory. Duets
of this species are of the “phonetic”
type. But there is no sexually dimorphic chorus
as in the case of the Kloss Gibbon.
More there are neighboring families
more we hear calls and longer. A single family
alone in a big forest area sings only 1 or 2
minutes and possibly not every day. We observe
this in Siju (Garo Hills District, Meghalaya)
where we heard one call the first day and nothing
after for four days. In Balpakram, the family
that we observed sang 2 to 5 minutes per day,
everyday. On the contrary, the groups observed in
the village sacred forest (Silbagri, Garo Hills)
sang from 20 to 45 minutes per day because of the
proximity of other families.
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