Zoo gorillas have evolved their own call to get food and attention from their caretakers, new research finds.
It’s been dubbed the “snough” by scientists at the University of Georgia — because it sounds somewhere between sneezing and coughing.
This is the first time ‘complex vocal learning’ has been identified in western gorillas, where they learn to make new sounds when they encounter new situations.
Outside of humans, it’s only been found in songbirds, parrots, hummingbirds, whales, dolphins, porpoises, pinnipeds — and recently, elephants.
Lead author Professor Roberta Salmi said: ‘Evidence for the ability to produce new calls by imitating sounds is rare in the animal kingdom.
“Attention calls from captive gorillas resemble a sound between sneezing and coughing that we called ‘snough’ or AG for ‘attention getter.'”
Zoo gorillas have evolved their own call to get food and attention from their caretakers, new research finds. Pictured: Sukari the gorilla at Zoo Atlanta, who participated in the experiment
The findings, published today in PLoS ONEwere the result of a series of experiments at Zoo Atlanta.
Eight gorillas were taken individually to an enclosure, and either a known container, a bucket of grapes, or a container with a bucket of grapes stood three feet from the cage – in plain sight but out of reach.
Their responses were then videotaped over the next 120-second period, and it was found that they most often cast their votes when the food and caregiver were present together.
They also often spoke with atypical sounds of sorts that: were similar to sneezing and coughing.
These AGs were usually single sounds, but in a few cases they were part of a longer sequence of two to four spaced about a second apart.
Each lasted about one-fifth of a second and was often accompanied by an exaggerated mouth opening and a gentle but quick repeated slapping or covering of the head or face.
An analysis confirmed that they differed acoustically from common gorilla calls such as grunts, which use them as contact calls, and hums, which require food in the wild.
Frequencies of attention-grabbing calls from three gorillas; Kudzoo (A), Macy (B) and Sukari (C). They are acoustically different from ordinary sounds such as growls and the demand for food in the wild
Male gorillas beat their chests to show females how big and fearsome they are
Analysis of wild male mountain gorillas in Rwanda reveals that a male’s drumming reveals their size.
German researchers also found that larger gorillas make a deeper sound when beating their chests than their smaller peers, and each individual’s thumping pattern is unique.
It is thought that when silverbacks hit their muscular torso, they broadcast their dominance and size to rival males while simultaneously trying to impress females who may be potential mates.
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A examination of recordings from other zoos revealed that the phenomenon is not unique to Zoo Atlanta.
Video footage from 15 of the individuals showed the call was produced by at least five women and one man housed in four different facilities.
Professor Salmi said: ‘Respondents attributed the use to as many as 33 gorillas housed in 11 different zoos in the US and Canada.
“These results show that gorillas can modify their calls to produce a new sound, and furthermore confirm that they can intentionally produce their calls and gestures to alter the attentional status of their caretakers.”
Western gorillas in Zoo Atlanta use a variety of cues to attract human attention, including vocalization, auditory and non-auditory gestures.
These include soft low-frequency vocalizations, banging or clapping, and shaking or waving a body part are some of the most common signals.
The “snough” has not been described before in the repertoire of wild gorillas, Professor Salmi said.
She added: “Our research results indicate that it is used specifically to get people’s attention, suggesting that gorillas, like other monkeys, are able to produce new sounds when they encounter new contexts.”
Eight gorillas were taken individually to an enclosure, and either a known container, a bucket of grapes, or a container with a bucket of grapes stood three feet from the cage – in plain sight but out of reach. Shown: Graph showing the average number of vocalizations, attention-grabbing sounds, and gestures in the three conditions
The researchers say future work should try to better determine the magnitude and patterns of ‘snough’ transmission across captive populations.
It can also judge whether it is an existing call type, or a modulated version, used in a new context by comparing it to the entire vocal repertoire of the zoo gorillas.
The researchers were unable to conclude how the AG sound originated in the gorillas, either randomly or learned from observing humans.
However, they speculate that the cough-like sound caught the attention of the caretakers as they monitor their health, and the primates may have noticed this trend.
Professor Salmi said: ‘These findings represent one of the few evidences of spontaneous new vocal production in uncultivated individuals of this species, supporting the uptake of great apes as moderate vocal learners and perhaps demonstrating an evolutionary function of a flexible vocal repertoire.’
Monkeys can recognize a friendly face, according to a new study, but they can’t help but stare at strangers
Primates living in zoos can recognize a friendly face, especially their caretakers, but can’t stop themselves from staring at strangers, according to a new study.
Researchers at the Johns Hopkins University School of Medicine in Baltimore, Maryland, studied the different ways monkeys interact with caretakers and visitors.
They tested a dozen great apes in zoos living in social groups at Chicago’s Lincoln Park Zoo that could use a touchscreen and let them look at pictures of faces.
The primates clearly experienced different interactions with familiar humans, such as the zookeepers who care for them, compared to those with unfamiliar humans, such as the large number of zoo visitors to whom they are regularly exposed.
Those they didn’t know got more attention than the guards, they found, suggesting monkeys spontaneously categorize humans based on familiarity.
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Primates living in zoos can recognize a friendly face, especially their caretakers, but can’t stop themselves from staring at strangers, according to a new study. stock image