Fixed stare, open mouth, head bobbing. From a 1974 children’s book by Michael Boorer, The Life of Monkeys and Apes. I’m a big fan of the the fellow on the right, the siamang. I wish I had special vocal sacs.
Threat II: Gorilla Threat. The stages are hooting, symbolic feeding, hurling vegetation, chest beating, running sideways and ground thumping. I think I used to work with this guy, actually.
ADOXOBLOG 
Reblogged this on Alistair Gentry.
Within one species, there are dialects, but amazingly chimps from Africa understand or respond to some of the signals of Cambodian Macaques. So, there are similarities in language across the species. The Macaque language is very interesting.