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actively for me to be sure. All very vocal. Lots of Growls, Grunts, Roars, Trills, Wails, WWB, Hyaena, and series of Grunts in Pumping rhythm. All mixed up and intergrading.

Then the inds drift away. Apparently breaking up into two groups of two each. 

I am quite baffled by the social relations among all these individuals. Perhaps I came upon a large group of at least 6 adults and 1 infant just as it was breaking up, after "clustering" during the rain. This would conform to some of my observations near Valparaiso. And if the interpretation is correct, it would suggest that this species has a social organization rather like Ateles with regular groups and sub-groups. 

Another possibility seems equally probable, however. I may have come across the animals when they were engaged in a territorial dispute. Perhaps 2 adults vs 2 adults + 1 infant. Or 4 adults vs 2 adults + 1 infant. This would help to explain the relatively great aggressiveness of at least 1 individual. And also the great range of vocalizations. 

In any case, it is obvious that this species has a very, very, very elaborate vocal repertory. Roars, Grunts, Growls, series of Grunts in Pumping rhythm, Wails, WWB, Hyaena, and at least one kind of Trill (are there several kinds?) apparently all intergrade in complex ways. The whole thing seems to be at least as