Mountain gorillas (gorilla beringei beringei) may be communicating with other members of their troop when they rise up on their hind legs and beat their chests with their hands to produce a loud, hollow sound. This is the conclusion of a study led by zoologist Edward Wright, from the Max Planck Institute for Evolutionary Anthropology in Germany. He and his team monitored 36 adult gorillas in Volcanoes National Park in Rwanda, Africa, between November 2015 and July 2016. They used laser cameras that allowed them to estimate the size of each animal. The group analyzed the recordings and found that the frequency of the sound is related to the size of the gorilla—the bigger the animal, the deeper the sound (Scientific Reports, April 8). Larger gorillas have bigger air pockets near the larynx, which would allow them to produce deeper sounds. According to the researchers, chest beating serves an efficient way for a male to communicate his size, attract mates, and warn off competing males.
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A very informative gesture
Jordi Galbany / Dian Fossey Gorilla Fund
