Silence is something like an endangered species. The experience of silence is now so rare that we must guard it and treasure it (Gunilla Norris).
These diurnal, lesser apes are monogamous. Each pair defends its territory
to keep all other gibbons out. Gibbons are very vocal and perform duets at different times of the day. The female starts the call with the male joining in later. The duets not only serve to further bond the pair but also to advertise their location and warn others to
White-handed gibbons are listed as endangered. Because gibbons are strictly arboreal, the logging of their home range has had drastic effects.