In the 25th year of the BBC's Natural History Unit. the second half of a series in 26 parts. Narrator
David Attenborough
23: Primate Territories
The kind of sound which we make with larynx squeezed rigid and emotion out of all control Is, for the indri, a song.' Alison Jolly of Rockefeller University, New York, and David Chivers of Cambridge
University, show how the wail of the indri is used to defend home territories, while the bark of the howler monkey serves to space out family groups.
Written and produced by MICHAEL BRIGHT BBC Bristol