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Chimpanzees use vocal communication to coordinate hunting

Chimpanzees don’t only forage for fruit. From time to time they also hunt smaller monkeys in the canopy in order to acquire protein-rich meat. Since these monkeys are usually very agile, chimpanzees are most successful in catching them by having their conspecifics hunt alongside them.

According to a team of researchers led by the University of Zurich (UZH) and Tufts University, chimpanzees often use communication to coordinate their cooperative behavior during hunting. By producing a specific type of vocalization called a “hunting bark,” they manage to recruit more group members to the hunt, which helps them capture their prey more efficiently.

The scientists studied over 300 hunting events recorded during the last 25 years at the Kanyawara chimpanzee community in Uganda, and discovered that, by making bark vocalizations, the wild apes catalyze group hunting. “Chimps who produce hunting barks provide information to those nearby about their motivation to hunt, and this information may persuade reluctant individuals to join, boosting the overall chances of success,” explained study lead author Joseph Mine, a doctoral student in Comparative Language Science at UZH.

Since hunting monkeys in dense tropical rainforests where visibility is significantly restricted is challenging, vocal communication allows chimpanzees to be more efficient. “Strikingly, following the production of hunting barks, we observed more hunters joining, greater speed in beginning the chase, and a shorter time to make the first capture,” said study senior author Zarin Machanda, an expert in Chimpanzee Behavioral Ecology at Tufts University.

While it is clear that such vocal communication makes hunting more effective, more research is needed to clarify why barks have this effect. “At the moment it is still unclear if these barks are given intentionally to coordinate the precise actions of the group, or whether they simply advertise an individual’s decision to hunt, which in turn, increases the likelihood of others joining them, and with more hunters they are more effective,” said study co-author Simon Townsend, an associate professor of Animal Communication at UZH. 

This study suggests that the relationship between group communication and cooperation – which is fundamental in humans and led to the emergence of language and the complex forms of cooperation modern humans engage in – has very deep evolutionary roots.  “Our results indicate that the relationship between vocal communication and group-level cooperation is ancient. This link seems to have been in place for at least seven million years, since our last common ancestor with chimpanzees,” Mine concluded.

The study is published in the journal Science Advances.

By Andrei Ionescu, Staff Writer  

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