According to new research, zoo gorillas have created their call to seek food and attention from their caregivers.
Scientists at the University of Georgia have dubbed it the “snough” because it sounds like a cross between a sneeze and a cough.
This is the first time that ‘complex vocal learning has been observed in western gorillas, in which they learn to produce novel sounds in response to unfamiliar stimuli.
Only songbirds, parrots, hummingbirds, whales, dolphins, porpoises, pinnipeds, and, most recently, elephants have been confirmed to have the virus.
Professor Roberta Salmi, the study’s lead author, stated, “Evidence for the ability to make fresh cries by imitating sounds is uncommon in the animal realm.”
The attention-getting calls of captive gorillas resemble a sound between a sneeze and a cough, which we have dubbed “snough” or AG for “attention getter.”
Today’s findings in PLoS ONE were the result of a series of tests conducted at Zoo Atlanta.
Individually, eight gorillas were placed in a pen, and either a familiar keeper, a bucket of grapes, or a familiar keeper plus a bucket of grapes was stationed one meter away, within sight but out of reach.
Their reactions were subsequently captured on film over the next 120 seconds, and it was discovered that they vocalized most frequently when both the food and keeper were present.
In addition, they frequently produced species-atypical sounds resembling a sneeze and a cough.
In most instances, these AGs were single sounds, but in a few instances, they were part of a longer series of two to four sounds separated by about a second.
Each one lasted approximately one-fiftieth of a second and was frequently accompanied by an exaggerated mouth opening and a repeated, soft but swift slapping or covering of the head or face.
Analysis revealed that they were acoustically distinct from grunts, which are used as contact sounds, and hums, which are used to request food in the wild.
An examination of recordings from various zoos found that Zoo Atlanta is not alone in experiencing this behavior.
Video footage of 15 of the inmates revealed that at least five girls and one male residing in four different facilities made the call.
Professor Salmi stated, “Respondents ascribed its use to as many as 33 gorillas held in eleven zoos throughout the United States and Canada.”
These findings reveal that gorillas may adjust their cries to make a novel sound and confirm that they can produce their calls and gestures on purpose to alter the attention status of their carers.
Western gorillas at Zoo Atlanta employ a variety of signals, including vocalizations, and audible and non-audible gestures, to attract human attention.
The most typical signs include mild, low-frequency vocalizations, thumping or hand clapping, and shaking or waving a body part.
Professor Salmi stated that the ‘snough’ was not previously described in the repertoire of wild gorillas.
She said, “Our study results indicate that it is employed expressly to draw the attention of humans, suggesting that gorillas, like other primates, are capable of producing novel sounds in novel circumstances.”
Future research, according to the researchers, should attempt to determine the scope and patterns of ‘snough’ transmission among captive populations.
By comparing it to the whole vocal repertoire of the zoo gorillas, it might also determine if it is an existing call type, or a modified variant, employed in a new situation.
The researchers were unable to determine whether the gorillas learned the AG sound by chance or by studying people.
However, they hypothesize that the cough-like sound caught the attention of the caretakers because they are monitoring the primates’ health and that the primates may have noticed this tendency.
Professor Salmi stated, “These findings are one of the few pieces of evidence of spontaneous novel vocal production in non-enculturated individuals of this species, supporting the inclusion of great apes as moderate vocal learners and possibly demonstrating the evolutionary function of a flexible vocal repertoire.”
