Why Do Male Gorillas Beat Their Chests? The behavior chest beating by Male Gorillas – Silverbacks has been exposed to audiences all over the world since King Kong first appeared on the silver screen in 1933.
However, it may surprise you to learn that while scientists have speculated about the percussive display’s meanings, actual evidence for why male gorillas sometimes pound their chests has been scarce.
Chest beating by male gorillas “silverback” is an extremely impressive display, it can be a bit frightening. You don’t want to get in the way.
Interestingly, while a male mountain gorilla’s hearty chest beat would seem to signal aggression, the new research by Wright shows that the behavior may actually prevent violence between the massive animals, which can top out at nearly 500 pounds.

Mountain Gorillas live in tight-knit family groups led by silverback males, whose authority is constantly being challenged by other males. By advertising is constantly being challenged by other makes. By advertising the size, mating status, and fighting ability via sounds that can travel long distances through thick rainforests, the silverbacks are signaling would-be challengers that they better think again before starting a ruckus.
To study the chest beating behavior in never-before-seen detail, wright and his colleagues spent more than 3,000 hours observing endangered mountain gorillas at Volcanoes National Park in Rwanda
While battling biting insects and navigating the rugged, mountainous terrain of the park, the scientists observed more than 500 chest beats from 25 different males between 2014 and 2016. They stayed at a safe distance from the animals, which have been habituated to the presence of researchers but remain highly vulnerable to human diseases.
The scientists, whose work was funded in part by the National Geographic Society, used audio equipment to record the frequencies of the chest beats, as well as the number of beats and duration of each display. Finally, they searched for relationships between these variables and the gorillas’ sizes. To do so, the team analyzed photographs to measure the maximum breadth of each animal’s shoulders.
The results showed that the biggest mountain gorillas produced sounds with lower frequencies than small gorillas – possibly because bigger gorillas have larger air sacs near their larynx. This means that chest-beating isn’t just a visit display, but what the study calls an “honest signal of competitive ability” – not unlike the alligator’s rumble or bison’s bellow.
Although the previous studies showed that a gorilla’s body size is linked to dominance and reproductive success, the idea that chest-beating also communicates some of that information was speculative according to the study, published today in Scientific Reports.
Robert Salmi – a primatologist and director of the Primate Behavioral Ecology Lab at University of Georgia says “We thought and suspected, but there was no actual date to support this claim.
Kong’s Calling Card
Though chest-beating is common in movies and other pop culture portrayals, there is still plenty we get wrong about this behavior.
For starters, real-life gorillas don’t strike their chests with balled up fists. Rather, they cup their hands, which amplifies the sounds. Also, they rise from a sitting to a standing posture, perhaps as another way to ensure that the thumps can be heard more than half a mile away.
Silverbacks beat their chests most often when females under their protection are entering estrus, the time they are most ready to mate. But it is not like males are banging on the drum all day, as they are often portrayed doing in movies.
In fact, Wright found that each male beat its chest an average of just 1.6 times every 10 hours. Lower-level male gorillas, or subordinates, also perform the chest-beating behavior, as do baby male gorillas when they are playing.
Wright says there doesn’t seem to be a relationship between how big or dominant a male is and how many times it strikes its chest, or how long its display lasts. But a sequence of chest beats may potentially communicate an animal’s identity, or “individual signature,” to other animals, he says.
Not-so-gentle giants
Though gorillas are equipped with gigantic muscles and long canine teeth, the animals come to blows only rarely. Wright believes this is at least partly because chest-beating allows males to size each other up without getting physical.
“Even if you are likely to win a fight, there is still quite a high – risk factor,” he says. “These are large, powerful animals that can do a lot of damage.”
To smaller males, the sound of a silverback’s chest-beat may discourage them from approaching. Similarly, a silverback may hear the beats made by a smaller male nearby and decide that he’s too puny to bother with.
Because chest-beat peak frequency syncs up with body size – which is itself linked to dominance and reproductive success – female gorillas have plenty of reasons to listen in on the displays, too. Particularly impressive chest-beating might lure females away to a nearby group like a siren’s long, though this has not yet been studied.
Salmi has also studied chest-beating in closely related western lowland gorillas. Intriguingly, this species also performs a hand-clapping behavior- apparently as a way to alert others to potential danger – this is so far not been observed in mountain gorillas.
Considering the new study’s results, the next step is to see how other gorillas use the information encoded in chest-beating sounds, Salmi says.
“It will be very interesting.” She says. “To see how hearing chest beats in their environments might affect their movements and decision-making as to which areas of their home range to use.”